Yes, absolutely the right decision to go with the new replacement board. As you say, over-voltage can result in obvious damage to parts but also hidden damage that might not become apparent until sometime later. I have experienced this with equipment brought to me for repair. I was able to get the unit back up and running, but some months later it started to exhibit strange behavior and the only way to ensure longevity of operation was to change out the main board.
Sad to say I have been down that same road. Back in February my 50A linear supply suffered a series pass transistor fault that fed my radios nearly 24V instead of 13.8V. Unfortunately the crowbar circuit did not last quite long enough to blow he fuse either, so the radios saw the full rail voltage. Thankfully no major damage was done and most of the damage to the radios was confined to the TVSS diodes which ultimately took out the fuses after sacrificing themselves. For the initial power on test afterwards and after servicing I like to use my variable bench supply to control any fault current by dialing in a maximum amperage just above the normal expected idle/receive current for the radio combined with a reduced input voltage if 12V. That way if there is a terrible fault very little additional damage will be done. For the transmit test I do the same by increasing the current limit to an appropriate minimum level and then try transmitting, first at low power, then higher, to see if the piper amplifier stage suffered any faults. Then measure all your voltage rails to look for low or high rails while safely powered on. Thankfully, I lucked out since most of the more sensitive radio circuits were protected by inline linear regulators which safely limited the let-through voltage to the more sensitive lower voltage rails and allowed the TVSS diodes and fuses the necessary time to do their jobs and sacrifice themselves. To find the source of any shorted components, like the TVSS diode, regulators, ICs, etc, use a good multimeter with 4-wire Kelvin probes to measure the resistance across the voltage rails at various points, the areas of minimal resistance are either the faulted shorted components or is electrically very near the affected component. This allows you to track down the shorted component(s) without leaving the device powered on for an extended amount of time during fault finding.
Have you heard of anyone who plugged an external speaker plug into the remote jack instead of the external speaker jack and now the tune button will no longer tune the external tuner on the IC-7100 ?
Great video! I have an Icom 703 that won't power up and was trying to figure out a troubleshooting procedure. You just explained it to me! I'm new to radio repair so this was very helpful. Thanks again Peter.
I think you made the right decision in the end Peter. Even after fixing the original board more problems could show up down the road at a later time. Specially since this was a brand new unit. You did do some awesome troubleshooting there, Thanks foe another great video Peter. 73
Hi Peter. We are ok my friend. Just so much work here to do. Today I decided to just come out to the shop and do some clean up. It is in a mess from moving stuff around due to heavy water leak in front room. Thanks for asking. 73
wow, the patience of a saint to go through all of that, halfway through the video I thought "I'd just buy a new board" absolutely brilliant and a spot on decision
I have done exactly the same with my FT-817ND... Forget to change from 28V which I have use previously to 13.8 when connecting Yaesu. Fortunately for me the only damages were the electrolytic capacitor (which exploded) and fuse at the very beginning of the circuit. More lucky then clever. Great video(s), I really enjoy watching for months. Huge knowledge sharing - thank you !
Thank you for a great video ! It made me check the specs. in the Icom IC-7100 Service Manual. It states the voltage is 13.8 Vdc +/- 15% e.g. 11.73 ~ 15.87 Vdc. As I intend to use an IC-7100 abord our little boat and use the 12 Vdc net, I measured the voltage there as well: when on shore-charge the maximum voltage (during wintertime) is 14.8 Vdc so no problem there, at anchor the voltage drops to a minimum of 12.2 Vdc before the generator kicks in to 14.3 Vdc so no problem there as well. Not a bad idea to measure the max. and min. voltages of say, your car or mobile home AND checking the specs. of your $$$ set before installing it, only to see it go up in smoke.
That reminds me of a unit that has been hit by lightning. It may only need a fuse to get it going but soon after that weird things start happening. I knew that board was damaged further than you thought. You were being optimistic with the board but when the next component up the line failed you knew it was a losing battle. Good video and glad you got a new board. You can put a seal of approval on the radio and not worry about a call back to soon. Thank you for the video.
Hi Peter, The 24V will have a cascade effect on all those IC's not rated for that voltage. I hope the radio came up to spec when you finished your testing. WB3BJU
Better late than never. I just came across this video, even though I have been scribed for some time. I too was using an external Liner type power supply. It was equipped with over/under voltage and current protection. However, the reaction time of my older supply apparently was not fast enough to overcome the problem to save my radio. The 24 VDC was directly applied to my ICOM 718 's 12 volt input supply. The result was it got toasted! and became a parts box. The good news is this was not connected to one of my newer more expensive Icom radios. There comes a point where you need to make a decision. How far do you go in investing time and money changing out components, or how much do you invest in new circuit boards before writing the radio off completely. A belated thank you for making a posting this video.
Changing the main-board was the best option my friend.. You can never be sure what has suffered in an over voltage event such as this. At least now the customer knows his radio is as good as new again now. Regards John
I don't know if you charge by the hour but I think you made the right call on this one. At some point the time involved would rack up a bill that would buy a new radio.
A good call on replacing the entire PCBA. Component level repair not cost effective if there are multiple failures and possibly other components that were stressed
Last week I took a chance and paid too much for a not-working IC-7100 main unit. Up to J701 I had exactly the same symptoms, but after replacing the blown apart ferrite bead, I slowly increased the current limit on my bench power supply and saw there was a short on the main board. Limiting the power output to 1W and using a thermal camera, I found the short is in the main CPU. Unfortunately the main CPU is an out-of-production Renessas part that no regular distributor has in stock. I'll contact Icom Parts USA tomorrow (Monday) and see what parts they have. Who knows, I may also have additional failures. Maybe a new main board is in my future too, but darn it - I've already spent too much on this unit. In my case the causing event is unknown, since I bought the radio "parts or repair" on ebay. However, I have a suspicion that something bad, like a live Ethernet cable, was plugged into the Controller jack. In what I think is a poor design move from Icom, the IC-7100's two 8-pin modular "RJ45" jacks are not keyed. Also some signals at the Controller jack (such as PWRK or "Power Key") go directly to IO pins on the main CPU. I believe plugging an Ethernet cable into the Controller port on the IC-7100 might instantly kill the main CPU.
You should limit the supply current, so you won't damage the PCB when a component blows up. I would replace any components that exceeded their maximum ratings, before even connecting the power back after replacing the first chip inductor. Probably, the regulator and the DC-DC converters took a hit from the 24V supply. Having said that, good repair.
What was the cost of a new board? Always discuss the costs of parts (when they are expensive) so we can learn economics of your decision to get the board rather than continuing diagnosis. What if there were further problems (on other boards)? What would you do then?
Dennis Fitz It is actually quite easy to do with hot air or infrared, so much so that I would often much rather desolder an SMD board than a through hole board, especially if one lacks a vacuum desoldering gun for through hole rework (thankfully I have such, but many do not). SMD rework can be nice since you do not necessarily need to pull a board in order to replace a component so long as you have good access to the component from the top side since there are no underside leads to deal with. While you do need a slightly different set of tools to efficiently rework SMD boards I really wish that both old timers and newcomers alike would come to realize that it is only a different way of doing things, not a more difficult way of doing things. I see so many who are convinced that fixing and building SMD boards is beyond their ability that it borders on upsetting because it really is not difficult, unless you are trying to work with the really minuscule parts, and I wish more would come to realize that they can do such work at home if they choose!
Thanks for the video. My IC7100 is scheduled to arrive day after tomorrow so I'll be sure to avoid using the 24v power supply. I'm surprised that ICOM doesn't protect the input power better - but at least the board protected the fuses from damage. 😊 I also agree with a previous poster that I'd love to see your desoldering/resoldering, but also disassembly of the cases. On the other hand, that was a very long video for the information provided. Just a friendly suggestion here: if you could avoid the use of the syllables "uh" and "ja-" and increase your speaking speed somewhat, I think you could produce the same information in remarkably less time.
I have noticed that everything that had been built since 1998 has less and less protection on power lines. And there are two reasons - It is cheaper and over-voltage\polarity-reverse is not being covered by the device warranty. Why does this happen? Because manufacturer cares about sales and reducing the support costs. Buy, burn it down, buy more and more!
Even though disheartning, sometimes complete replacement is the only logical answer. I'm sure the added cost is hard to deal with, but then again, it is not a total loss.
Nice troubleshooting. Shame on iCOM for not using a crowbar on the input. I think I would have gone with the original board and just repaired it if and when it failed.
They probably have one in their power supply - there has got to be some reason it costs $400 lmao. I love my IC2300H, but not enough to give it the icom SMPS lol
Great work, I can empathize with the owner. Puting too much voltage in the supply could cause heartache. It is a shame that you have to toss the original board after all of that troubleshooting.
Yes Peter, I too feel that you made the best decision to replace the whole board !! With a severe overvoltage like that, that voltage spike can destroy a large number of components unfortunately !! I feel bad for the owner too, but hopefully he will bea little more careful and thoughtful now too. !! good job on your part!! and good video!! John Bellas KC2UVN
That would be the sum of all fears. I hope that never happens to me. My Yaesu 991a cost me a bundle; they've gone up since 2017. I cannot imagine frying my radio before even keying it up for the 1st time. Cheers & 73 from W Rusty Lane K9POW in eastern Tennessee
I agree, sometimes its the only and better way to replace the whole mainboard. I hope a voltage overkill will never happen in my shack...Nice work and thank you very much for your very learnfull video presentation! 73 Ernest PA3DLP
ijust came across this vid during my search for an IC-R7100. Both fascinating and depressing! All that money.....and the owner doesn't check the proper voltage! Very sad.
I have a Yeasu FT-8900R which burns fuse when power is connected. This Radio was in my car and without eny use for few years, since my car had a serious main brakecylinder problem before we found what was wrong. My question is that could it be, forexample, dryed electrolytic capacitor in main voltage which causes short cut..? Certainly it´s not transmit unit because it´s not been used for meny years. I would be very greatful for eny information..
I own a Icom 7300 and it was *UNHOOKED from the power supply* . I was going to move the radio to another location and when I picked it up, the power supply leads touched together and I heard a loud snap! It was like there was stored voltage in the radio. When I went to hook it back up again, it wouldn't turn on. I checked the circuit fuse on the board and it was O.K. and the other fuses are all good. What do you think it could be? It still draws a little power when connected, though. Probably the power amp section drawing the power.
Thanks for the reply. I enjoy your videos! Well, at least I know better now to always keep the power cable completely disconnected when in storage. There's three caps right next to the circuit fuse where the power leads connect to the board and there's a 9v regulator right after it. My guess is that the caps were still charged quite a bit and by shorting the power leads, it damaged the regulators and possibly the caps too. So, I'm going to pick up a hot air rework station and order the parts that Icom was so nice to list for me on their online service manual!
I would like to know your opinion on those inexpensive Chinese radios in terms of ease of service, ease of getting replacement parts, [clarity of instructions etc...
Well Thomas you already pointed out all the problems why it does not make sense to buy a Chinese radio at the moment..May be the situation will change in the future but for now NO 73
Hi Peter, what kind of equipment and or trick are you using when removing components like the surface mounted dc-dc chip. Do you use a hot air soldering iron? , maybe you could make a video about this, when working in a close enviroment to ather components like the caps and coils around the chip. As always very good video, thank you for making them.
christopherkise Hot air and/or infrared are generally the best options for reworking surface mount boards, especially if you wish to avoid damaging the original component during removal (such as when removing components to isolate issues during troubleshooting), allowing for reuse of undamaged components when finished troubleshooting. You can also solder in the replacement components with hot air or infrared, though many components types may also be soldered using an ordinary soldering iron when required. Sometimes you may also need a large infrared preheater to actively preheat a board during rework if the circuit board contains large copper fills or ground planes that wick heat away to quickly to allow safe rework with only direct local heating (you would be surprised how much heat a copper ground plane can wick away!). In such cases, you would preheat the backside of the circuit board to a safe intermediate temperature (such as 100C) to reduce the amount of localized heat you will need to apply in order to solder or desolder a component -- lead free solders generally need to achieve at least 220C before liquefying, so heating the opposite side of the board to ~100C makes it easier to overcome the copper fill or ground plane so that you can achieve 220+C.
I put Kapton tape over caps and stuff around the IC that I'm removing with my Hot-Air Rework Station to help keep them from coming loose and blowing around. I also learned to use the lowest temp setting that will melt the solder.
In my days as a trainee radio/TV tech (47years ago), before any measurements were made, the three senses were used. Look over the board, smell, then heat check with a finger etc. Still holds true today.. GI0OTC
Hi Peter, i wonder if you had found this defect quicker with the thermal Camera. Just replacing the 2nd Coil and slowly bring up the Voltage until you see the shorted part. 73 de DK3JF Jörg
Another great repair video Peter. If you don't mind me asking a dumb question is 24 volts a standard voltage where you are? In the US about the only place you see higher voltages is the military and aviation. Just wondering how the owner accidentally hooked up to 24 volts. Mike
MikesRadioRepair Even here in the U.S. there are some higher powered HF radios and lower powered external amplifiers (say, 400-600W) that use a 24 to 28V, even 48/50V, external supply for their power amplifiers (the rest of the radio is often still operated from a 13.8V rail). The higher voltage both increases the linear range of the power transistors in the PA while also reducing the need for ultra-low impedances in the PA stage, and power delivery, to achieve the higher power output (consider how little impedance must exist to deliver 40-100 amps into a PA circuit, not just within the PA but also the wiring between the PA and power supply/battery) -- doubling the source voltage simplifies the design and power delivery versus 12-13.8V and allows for more reasonable wire gauges.
I love these videos. Additional benefit is I get to pick up a bit of German from the instruments at the back!! Spannung == Voltage! Great work. Question though - what is your thought on why the manufacturer doesn't put voltage protection on the input? Is it just a cost thing for them (as a commenter pointed out below) or is their some technical reason.
Thank you, glad that you liked it. Well regarding your question. I don't think that is a technical reson as it is no rocket science....I truly believe it is always cost reasons...73
WoW, you say right at the end that you do NOT want to drag it out too long, well I think that 47 minutes and 49 seconds is a bit too long, as at the end of the day, all you done was to replace a FULL NEW circuit board and NOT fix it as I thought that you would have done. Also how did you know that after fitting the new board, that on one of the other boards that there was no problems that could affect the new board ??? I am not saying that what you had done was easy, as I know I struggled in fitting surface components, as even me using the larger resistors, I struggle with. I did find that using a set of reverse tension tweezers that can hold the component in place, is for me a God send. But this getting older and having a double cataract surgery a number of years ago, as just had a eye test on Saturday (14/9/23) and being told that between my eye and the plastic lens that they put in, it is starting to go cloudy ☹️ and they might have to do laser eye surgery, then perhaps my eyes might become a bit better. But on the whole, good work. Bye from Knobby.
Just had a thought, that voltage step dove converter, I do not know why Icom never fitted one that could handle at minimum 25v to 30v. As if the done that, they would NEVER have the problem of accidentally connecting to a 24v power source. As some trucks use 24v along with some busses/coaches and even some boats. I know that the chance that someone uses 24v is not that common. But as I say, I bet when manufacture of the radio, it would not add that much additional work and also would not add to the cost of the radio, as how much do them step down IC’s cost, and Icom would be able to get them at a massive discount to the price that you or I would have to pay. Bye from Knobby.
really discouraged with icom. i literally order approx $22,000 a year in gear with the icom name on it ... i order from gigaparts which is excellent... one time i have a problem and icom will not stand behind it .. i order 2 icom 718 radios at a time, one time recently i get a case that is dented, " not the box the case" so i know it happened at icom , i do not blame it on gigaparts, there is no way it happened at gigaparts, it happened at the factory . was told i had to purchase a new case lid for $36.00 .. nice staff at icom but when it comes to customer service i am really truly disappointed. over not making it right they are willing to lose a customer that spends so much money on their product. .amazing......Attn icom. This will be posted in every area of the web i can find to copy and paste..
This customer took responsibility for their mistake and paid for the repair. Didn't complain to iCOM and threaten to lose their business unless they gave him something he didn't deserve. I'm going to buy an IC-7300 this year, and if god-forbid I dent the case, I'm going to pay the $36.00 for a new lid.
I had the same with Icom-UK. They are a waste of time. Brand new IC-9700 and an inductor went open after one week from new. It took my supplier to back me up before they would act under warranty. Icom tried to say it was my PSU that was not an Icom PSU (It is an Icom PSU), but I was mobile at the time running a straight 12V. They had no option but to fix it.
I was thinking it might be a good idea to add an anti-static pad to your work desk. Not only would it help with static discharge, but it would provide a slightly soft surface so as not to scratch cases when moving them and sliding them around the desk.
It is in any case important to have a ESD safe workspace and so is mine. The mat on the bench is completely ESD safe and connected to ground over 1MOhm. 73
After replacing the first chip coil you say "Ready to test" then jump to another toasted chip. I so much wanted to see the power-up procedure. Why did you not show that?
Hi, yes you are right that is always an exciting moment. I don't know how many videos you have seen from my collection but I have shown several time how I handle the ramp up. It is always a tightrope walk to decide what to show and what not as videos should really not get to long. And considering that my videos are always toooo long I decided to skip it here. Sorry hope you understand. Thanks for watching 73
24V mobile home? I don't know why new radios still don't use some zener or something to protect the input. I know the current is quite high and you'd have to do a purposely placed MOSFET shorting transistor but still what would this cost $2 extra for protection against this type of thing?
a common way to achieve overvoltage protection is a thyristor or transistor crowbar. It will blow the fuse in case of overvoltage by introducing a short in the supply line. It does not take a very beefy transistor or proper cooling as the shot circuit current flows for merely a few ms before the fuses blow.
With this auto type fuse. You'd need a clamp to withstand probably 200% of this www.littelfuse.com/~/media/automotive/catalogs/littelfuse_fuseology.pdf or 200A for 1 second. That's some serious power (2.5 kJ = 12.7V * 200A ) and PCB tracing! Even with 2oz foil that probably wouldn't work. This is good reason to NOT use less expensive auto fuse as it's more slow blow than fast acting. More appropriate would be fast acting and possible clamping method then. In looking at this that auto type fuse would protect the radio from almost nothing, weniger als nichts!
Ham4Ham Many radio manufacturers do include at least some degree of input protection, typically either a high power rated TVSS diode or crowbar circuit designed to try and clamp the input voltage long enough to blow the input fuse(s). These also can provide protection from polarity reversal faults. Such are typically connected directly across the input just inside the radio so that little, if any, current passes through the PCB foil as they are placed directly across the input leads and typically joined to them with a heavy blob of solder. I was a bit surprised that iCom does not appear to have done such in this radio as it does quite often work to protect the radio from catastrophic damage and usually only sets one back a couple dollars worth of parts (namely the TVSS diode and fuse) -- much better than having to replace a main or PA board just because of a moments carelessness.
Yes 24 Volt is a great possibility !! If that motor home is equipped with a diesel engine, it more than likely has a 24 volt starter to turn it over quicker / easier. I had a MACK truck that had the END 864 engine that's 864 cubic inches !! and the truck had 4 big 6 volt batteries ! 2 batteries in parallel on each side of frame with 4 wires going to a HUGE relay under the passenger seat to "WIRE the two sets of batteries in series for a 24 volt start then back to 12 volt run!!!! A complex setup, so I can see making everything 24 volt, it would make things simpler!!! John BellasKC2UVN.
Hi my real time clock battery backup on my IC7100 is not holding much charge anymore as it dies after a few days switched off. I was trying to see how easy it would be to swop and wanted to know is it soldered into place? I think it's near to the SD card slot. any chance you could have a quick look on the broken pcb and let me know. Thanks!
Peter now I relook and see radio supply has 30A fuse. Why would this be? This seems crazy? You could have 5kJ (5kw) inside the radio momentarily during fault conditions. I am curious on peak current measurement for 100W radio with maybe 25 ohm load over 10mS. Because RMS should still always be ~100W maximum which would only be near 8A. This seems could even be fire risk potentially from being such a wrong size.
Ham4Ham While 30A is a little high (most 100W HF radios will use 25A fuses), one must keep in mind that a 100W HF radio will draw around 21-23A during transmit at full power, particularly in FM and digital data modes. That peak operating amperage really sets a hard limit on how small a fuse value can be used since such current levels can be sustained for minutes at a time when operating in certain modes, plenty of time to regularly blow an undersized fuse. For this reason most 100W HF radios will be fused at around 25A. However, many radios will also include a TVSS diode or crowbar protection circuit on their input designed to help protect the electronics by reducing let through voltage by placing a near dead short on the input allowing the fuse to quickly blow. Such can also provides a good level of protection against polarity reversal. Such protection circuits help to reduce the risk of catastrophic faults by limiting damage in many cases to just a few dollars in replacement components (namely the TVSS diode and fuse(s)). I am uncertain where you are getting your 5KW figure for a 30A fuse at 13.8VDC +/-15% ( ~414W), unless you are trying to figure peak let through in the moment before a fuse blows (but such is a rather pointless spec as it is time weighted and one seldom knows the system fault impedance and duration time ahead of time, after all, if not for some resistance, a fuse will allow infinite let through wattage for an infinitely short duration before it blows).
RF output part of radio is only 30% efficient? Needing nearly 300W input to output 100W RMS? I never actually measured mine to see. 5kW would be near a 1 ms fault from the I^2T. Power supply couldn't do this, but car battery could. So filter suggests by 30A size burns enough over 22A for a 25A to not work.
Hi Peter, as always great video, even if have not been able to fix it by changing some little components (it's the 1st video of this kind isn't it?) But if it is toasted too much, even the "wizard" has no chance ;) 73's
LOL yeah that' it. Well to be serios you always have to have the costs for the om in view so there is a Point wehre you have to Go another way. Personals I would Love to See what the Problem was. 73
Excellent video as always Peter. I always learn something from listening to your methodical approach to troubleshooting and this video is no different. Great job. Out of curiosity, what was the cost of that replacement board?? That radio retails for nearly $1000 here in the US. 73 de N0BPS
TRX Bench Ouch! That is a lot of pain for a few seconds, and a very human, act of momentary carelessness! My heart really goes out to him as I have had to repair my radios as well after a power supply fault allowed the unregulated rail (about 20-24V) through to my radios. No matter how many electronics I have repaired over the years, my heart still sinks whenever I see that magic smoke (they really ought to sell refills of magic smoke). This case is a good argument for using Powerpole connectors with different keying for your 12V and 24/28V power supplies so that they may never be attached to the wrong supply. I use them extensively for my gear as they really go a long ways to reducing accidents when connecting and disconnecting equipment (especially the dreaded polarity reversal). We all make dumb mistakes every now and then no matter how careful our personality.
What sad moments...maybe a little varistor as power supply protection, could save or reduce risk for that kind of radio. Have you used one for the 2nd new icom board !? By the way..what do you think, why icom or other usually not used a cheap overvoltage protection ?! '73 :)
or atleast regulatorchip that have a 27V at maximum input....instead ov 20V.. little difference at coast at componentlevel but i think costumers will accsept to pay a little more for a radio thats protected for voltages up to 28V
one of the feet is missing in the front. Why not design a rotating and flip the radio over in the form of a frame that holds the radio and suspends it on the workbench?
Yes, absolutely the right decision to go with the new replacement board. As you say, over-voltage can result in obvious damage to parts but also hidden damage that might not become apparent until sometime later. I have experienced this with equipment brought to me for repair. I was able to get the unit back up and running, but some months later it started to exhibit strange behavior and the only way to ensure longevity of operation was to change out the main board.
Sad to say I have been down that same road. Back in February my 50A linear supply suffered a series pass transistor fault that fed my radios nearly 24V instead of 13.8V. Unfortunately the crowbar circuit did not last quite long enough to blow he fuse either, so the radios saw the full rail voltage. Thankfully no major damage was done and most of the damage to the radios was confined to the TVSS diodes which ultimately took out the fuses after sacrificing themselves.
For the initial power on test afterwards and after servicing I like to use my variable bench supply to control any fault current by dialing in a maximum amperage just above the normal expected idle/receive current for the radio combined with a reduced input voltage if 12V. That way if there is a terrible fault very little additional damage will be done. For the transmit test I do the same by increasing the current limit to an appropriate minimum level and then try transmitting, first at low power, then higher, to see if the piper amplifier stage suffered any faults. Then measure all your voltage rails to look for low or high rails while safely powered on. Thankfully, I lucked out since most of the more sensitive radio circuits were protected by inline linear regulators which safely limited the let-through voltage to the more sensitive lower voltage rails and allowed the TVSS diodes and fuses the necessary time to do their jobs and sacrifice themselves.
To find the source of any shorted components, like the TVSS diode, regulators, ICs, etc, use a good multimeter with 4-wire Kelvin probes to measure the resistance across the voltage rails at various points, the areas of minimal resistance are either the faulted shorted components or is electrically very near the affected component. This allows you to track down the shorted component(s) without leaving the device powered on for an extended amount of time during fault finding.
When the second chip popped, I thought maybe the board would need to be replaced. You do very good work. I always enjoy watching your videos.
Thanks for feed-back! 73
Have you heard of anyone who plugged an external speaker plug into the remote jack instead of the external speaker jack and now the tune button will no longer tune the external tuner on the IC-7100 ?
Great video! I have an Icom 703 that won't power up and was trying to figure out a troubleshooting procedure. You just explained it to me! I'm new to radio repair so this was very helpful. Thanks again Peter.
Thanks glad that you like it. 73
I think you made the right decision in the end Peter. Even after fixing the original board more problems could show up down the road at a later time. Specially since this was a brand new unit. You did do some awesome troubleshooting there, Thanks foe another great video Peter. 73
Thank you Buddy! Are you and yours okay??? I honestly hope my friend 73
Hi Peter. We are ok my friend. Just so much work here to do. Today I decided to just come out to the shop and do some clean up. It is in a mess from moving stuff around due to heavy water leak in front room. Thanks for asking. 73
Very good to hear that Buddy! Hope the damage is not to serious as most of the time water is destroying a lot.. Take care my friend
Very good to hear that Buddy! Hope the damage is not to serious as most of the time water is destroying a lot.. Take care my friend
GREAT troubleshooting as all ways Peter. Good call to put in a new board.
Thank you Grant 73
wow, the patience of a saint to go through all of that, halfway through the video I thought "I'd just buy a new board" absolutely brilliant and a spot on decision
lol well with a little patience we cb do it...Thanks for comment
@TRXLab If you can, maybe you can mention the cost (wholesale or retail) of that new replacement board. I'm a little curious.
I was thinking that board is sure in bad shape, and you found the other board. That was the best way to go!! Another Awesome video!!
I have done exactly the same with my FT-817ND... Forget to change from 28V which I have use previously to 13.8 when connecting Yaesu. Fortunately for me the only damages were the electrolytic capacitor (which exploded) and fuse at the very beginning of the circuit. More lucky then clever.
Great video(s), I really enjoy watching for months. Huge knowledge sharing - thank you !
Yea sometimes things simply going wrong...Thanks for watching 73
Excellent Peter, you can only go so far then it is better to replace. Another great video. 73 s from M3KQW
Yes sometimes it is a better decision to replace although when ever I can I avoid it... Thanks for watching Howard. 73
Thank you for a great video !
It made me check the specs. in the Icom IC-7100 Service Manual. It states the voltage is 13.8 Vdc +/- 15% e.g. 11.73 ~ 15.87 Vdc.
As I intend to use an IC-7100 abord our little boat and use the 12 Vdc net, I measured the voltage there as well: when on shore-charge the maximum voltage (during wintertime) is 14.8 Vdc so no problem there, at anchor the voltage drops to a minimum of 12.2 Vdc before the generator kicks in to 14.3 Vdc so no problem there as well.
Not a bad idea to measure the max. and min. voltages of say, your car or mobile home AND checking the specs. of your $$$ set before installing it, only to see it go up in smoke.
Great job Peter, my compliments, you are clear and precise, a great thumbs up
thank you
Hi Peter, I feel bad for the OM as you, but sometimes you have to just make the most sensible decision, as I think you did. Enjoyed the video. 73
Hi Larry yes I fully agree....Thanks for watching 73
This is a fantastic video of clearness and even i am a beginner, I was able to follow you.
Peter it is a joy to watch and listen to an engineer at work :)
Love watching your videos brilliant methodical, the Sherlock Holmes of ham radio
Thanks Peter, it's always a pleasure watching you work.
Thanks you Robert always glad to see you .. Cheers
That reminds me of a unit that has been hit by lightning. It may only need a fuse to get it going but soon after that weird things start happening. I knew that board was damaged further than you thought. You were being optimistic with the board but when the next component up the line failed you knew it was a losing battle. Good video and glad you got a new board. You can put a seal of approval on the radio and not worry about a call back to soon. Thank you for the video.
Sometimes you win and sometimes you loose...Thanks for watching 73
A great video Peter, well done! It was really interesting to see how easily maintainable the radio is!
Thanks for watching 73
Something I noticed right away as soon as you took the cover off, the 5 amp fuse in the radio is blown
excellent video i always learn loads from your videos keep you keep the good work going thanks again
Thanks for watching, glad that you like my videos... 73
Hi Peter,
The 24V will have a cascade effect on all those IC's not rated for that voltage. I hope the radio came up to spec when you finished your testing. WB3BJU
Hi Donald that is always the problem you never know what the over voltage did to the radio...Thanks for watching 73
Better late than never. I just came across this video, even though I have been scribed for some time.
I too was using an external Liner type power supply. It was equipped with over/under voltage and current protection. However, the reaction time of my older supply apparently was not fast enough to overcome the problem to save my radio. The 24 VDC was directly applied to my ICOM 718 's 12 volt input supply. The result was it got toasted! and became a parts box. The good news is this was not connected to one of my newer more expensive Icom radios. There comes a point where you need to make a decision. How far do you go in investing time and money changing out components, or how much do you invest in new circuit boards before writing the radio off completely.
A belated thank you for making a posting this video.
yeah that is wheat sometimes happens.. Thanks for watching
Changing the main-board was the best option my friend.. You can never be sure what has suffered in an over voltage event such as this. At least now the customer knows his radio is as good as new again now.
Regards
John
Hi John, you are so Right. Thank you for watching my friend Cheers
Another great video Peter. Very costly mistake on power up. Thanks.
Thank you Jerry! 73
I don't know if you charge by the hour but I think you made the right call on this one. At some point the time involved would rack up a bill that would buy a new radio.
This is better than any detective show on TV period!
Glad that you like it! 73
A good call on replacing the entire PCBA. Component level repair not cost effective if there are multiple failures and possibly other components that were stressed
Thanks for taking the trouble for troubleshooting
Thanks for watching 73
Great troubleshooting Peter...thanks for the video
Thanks for watching. 73
Last week I took a chance and paid too much for a not-working IC-7100 main unit. Up to J701 I had exactly the same symptoms, but after replacing the blown apart ferrite bead, I slowly increased the current limit on my bench power supply and saw there was a short on the main board. Limiting the power output to 1W and using a thermal camera, I found the short is in the main CPU.
Unfortunately the main CPU is an out-of-production Renessas part that no regular distributor has in stock. I'll contact Icom Parts USA tomorrow (Monday) and see what parts they have. Who knows, I may also have additional failures. Maybe a new main board is in my future too, but darn it - I've already spent too much on this unit.
In my case the causing event is unknown, since I bought the radio "parts or repair" on ebay. However, I have a suspicion that something bad, like a live Ethernet cable, was plugged into the Controller jack. In what I think is a poor design move from Icom, the IC-7100's two 8-pin modular "RJ45" jacks are not keyed. Also some signals at the Controller jack (such as PWRK or "Power Key") go directly to IO pins on the main CPU. I believe plugging an Ethernet cable into the Controller port on the IC-7100 might instantly kill the main CPU.
You should limit the supply current, so you won't damage the PCB when a component blows up. I would replace any components that exceeded their maximum ratings, before even connecting the power back after replacing the first chip inductor. Probably, the regulator and the DC-DC converters took a hit from the 24V supply. Having said that, good repair.
What was the cost of a new board? Always discuss the costs of parts (when they are expensive) so we can learn economics of your decision to get the board rather than continuing diagnosis.
What if there were further problems (on other boards)? What would you do then?
Yeah understand your intention but I have no invoice yet. It is under clarification... I expect the board to be around 400 bucks. 73
Good choice Peter.
Too much problems on that board. It would not be a good idea to keep it.
Nice work.
Thanks for watching. 73
I would really love to see you do the actual de-soldering and soldering of those surface mount components. I enjoy your videos
Yeah I should show it in one of the next Videos. Thanks for watching. 73
Nice decision, thanks !
Dennis Fitz It is actually quite easy to do with hot air or infrared, so much so that I would often much rather desolder an SMD board than a through hole board, especially if one lacks a vacuum desoldering gun for through hole rework (thankfully I have such, but many do not). SMD rework can be nice since you do not necessarily need to pull a board in order to replace a component so long as you have good access to the component from the top side since there are no underside leads to deal with.
While you do need a slightly different set of tools to efficiently rework SMD boards I really wish that both old timers and newcomers alike would come to realize that it is only a different way of doing things, not a more difficult way of doing things. I see so many who are convinced that fixing and building SMD boards is beyond their ability that it borders on upsetting because it really is not difficult, unless you are trying to work with the really minuscule parts, and I wish more would come to realize that they can do such work at home if they choose!
Thanks for the video.
My IC7100 is scheduled to arrive day after tomorrow so I'll be sure to avoid using the 24v power supply. I'm surprised that ICOM doesn't protect the input power better - but at least the board protected the fuses from damage. 😊
I also agree with a previous poster that I'd love to see your desoldering/resoldering, but also disassembly of the cases.
On the other hand, that was a very long video for the information provided. Just a friendly suggestion here: if you could avoid the use of the syllables "uh" and "ja-" and increase your speaking speed somewhat, I think you could produce the same information in remarkably less time.
I have noticed that everything that had been built since 1998 has less and less protection on power lines. And there are two reasons - It is cheaper and over-voltage\polarity-reverse is not being covered by the device warranty. Why does this happen? Because manufacturer cares about sales and reducing the support costs. Buy, burn it down, buy more and more!
Sad, I have a 7100. Great radio. Great video as always.,
Even though disheartning, sometimes complete replacement is the only logical answer. I'm sure the added cost is hard to deal with, but then again, it is not a total loss.
Nice troubleshooting. Shame on iCOM for not using a crowbar on the input. I think I would have gone with the original board and just repaired it if and when it failed.
Yeah See your point but the demage was to huge Thanks for watching. 73.
They probably have one in their power supply - there has got to be some reason it costs $400 lmao. I love my IC2300H, but not enough to give it the icom SMPS lol
Great work, I can empathize with the owner. Puting too much voltage in the supply could cause heartache. It is a shame that you have to toss the original board after all of that troubleshooting.
You are right Thomas but watch additional video #129 and all is good now :-) Thanks for watching 73
Yes Peter, I too feel that you made the best decision to replace the whole board !! With a severe overvoltage like that, that voltage spike can destroy a large number of components unfortunately !! I feel bad for the owner too, but hopefully he will bea little more careful and thoughtful now too. !! good job on your part!! and good video!! John Bellas KC2UVN
Yeah John I agree. Thanks for watching 73.
That would be the sum of all fears. I hope that never happens to me. My Yaesu 991a cost me a bundle; they've gone up since 2017. I cannot imagine frying my radio before even keying it up for the 1st time. Cheers & 73 from W Rusty Lane K9POW in eastern Tennessee
yes agreed the sum of all fears....
I agree, sometimes its the only and better way to replace the whole mainboard. I hope a voltage overkill will never happen in my shack...Nice work and thank you very much for your very learnfull video presentation! 73 Ernest PA3DLP
Thank you Ernest! Yeah we don't want that at all! 73
Hello, good Video, Thanks. Can You tell me how much such a Mainboarl will cost? I have to replace mine. Thanks, 73 de Willi
Great video Peter.
Love your videos. Your camera work is fine. I'm looking forward to your next one.
Glad that you like my Video. Thanks for watching 73
Great video. Really enjoyed the fault finding.
Thank you Simon! Thanks for watching Cheers
ijust came across this vid during my search for an IC-R7100. Both fascinating and depressing! All that money.....and the owner doesn't check the proper voltage! Very sad.
Hi Andy, yeah that is how it goes sometimes....Thanks for watching 73
Love your work on the bench👍
Very interesting video. Keep up the good work Peter. A BIG thumbs up :)
Thank you Nina! 73
Your sprung multi-meter probes look very interesting.What make are they? Very informative video BTW.
great Works !! excellent video.
Thank you! 73
I have a Yeasu FT-8900R which burns fuse when power is connected. This Radio was in my car and without eny use for few years, since my car had a serious main brakecylinder problem before we found what was wrong. My question is that could it be, forexample, dryed electrolytic capacitor in main voltage which causes short cut..? Certainly it´s not transmit unit because it´s not been used for meny years. I would be very greatful for eny information..
I own a Icom 7300 and it was *UNHOOKED from the power supply* . I was going to move the radio to another location and when I picked it up, the power supply leads touched together and I heard a loud snap! It was like there was stored voltage in the radio. When I went to hook it back up again, it wouldn't turn on. I checked the circuit fuse on the board and it was O.K. and the other fuses are all good. What do you think it could be? It still draws a little power when connected, though. Probably the power amp section drawing the power.
that ishard to say....it can be anything sorry
Thanks for the reply. I enjoy your videos! Well, at least I know better now to always keep the power cable completely disconnected when in storage. There's three caps right next to the circuit fuse where the power leads connect to the board and there's a 9v regulator right after it. My guess is that the caps were still charged quite a bit and by shorting the power leads, it damaged the regulators and possibly the caps too. So, I'm going to pick up a hot air rework station and order the parts that Icom was so nice to list for me on their online service manual!
Great video! Thanks for sharing.
Impressive, i would have satrted crying. Good job.
I would like to know your opinion on those inexpensive Chinese radios in terms of ease of service, ease of getting replacement parts, [clarity of instructions etc...
Well Thomas you already pointed out all the problems why it does not make sense to buy a Chinese radio at the moment..May be the situation will change in the future but for now NO 73
Hi Peter, what kind of equipment and or trick are you using when removing components like the surface mounted dc-dc chip. Do you use a hot air soldering iron? , maybe you could make a video about this, when working in a close enviroment to ather components like the caps and coils around the chip. As always very good video, thank you for making them.
christopherkise Hot air and/or infrared are generally the best options for reworking surface mount boards, especially if you wish to avoid damaging the original component during removal (such as when removing components to isolate issues during troubleshooting), allowing for reuse of undamaged components when finished troubleshooting. You can also solder in the replacement components with hot air or infrared, though many components types may also be soldered using an ordinary soldering iron when required. Sometimes you may also need a large infrared preheater to actively preheat a board during rework if the circuit board contains large copper fills or ground planes that wick heat away to quickly to allow safe rework with only direct local heating (you would be surprised how much heat a copper ground plane can wick away!). In such cases, you would preheat the backside of the circuit board to a safe intermediate temperature (such as 100C) to reduce the amount of localized heat you will need to apply in order to solder or desolder a component -- lead free solders generally need to achieve at least 220C before liquefying, so heating the opposite side of the board to ~100C makes it easier to overcome the copper fill or ground plane so that you can achieve 220+C.
I put Kapton tape over caps and stuff around the IC that I'm removing with my Hot-Air Rework Station to help keep them from coming loose and blowing around. I also learned to use the lowest temp setting that will melt the solder.
A friend of mine once did the same thing... the radio made a warranty call and got a new operator...poor guy... wonder wat they did with him...
no this radio stands behind his operator and went back after surgery.
Thank you very much for share the repair skill , VY 73 de BD7PA
In my days as a trainee radio/TV tech (47years ago), before any measurements were made, the three senses were used. Look over the board, smell, then heat check with a finger etc. Still holds true today.. GI0OTC
Yes Alan it is all still the same :^) You can right start off again LOL. Thanks for watching 73
Another enjoyable video from you - thank you. Is the replacement board readily available to the consumer? How much? I would think quite a lot!
Hi, Thank you. Well in Europe any enduser can get it. 73
I find it quite amazing that i can understand him better when setting the playback speed to 2x ;)
Well very good. Then this Speed is Perfect for you. Thanks for watching 73
Your voice to brain synapsis translator converter is a bit overclocked :D
Hi Peter, i wonder if you had found this defect quicker with the thermal Camera. Just replacing the 2nd Coil and slowly bring up the Voltage until you see the shorted part.
73 de DK3JF Jörg
Hallo Jörg, ja das wäre ein gangbarer Weg gewesen. Ich muss zugeben ich hatte den Schaden als nicht so heftig vermutet....Danke fürs vorbeischauen. 73
Another great repair video Peter. If you don't mind me asking a dumb question is 24 volts a standard voltage where you are? In the US about the only place you see higher voltages is the military and aviation. Just wondering how the owner accidentally hooked up to 24 volts.
Mike
Thank you Mike! No 24 volts is no standard voltage so no idea why he has a 24 volt distribution in his shack. Take care 73
+TRX Bench
10-4. I bet he will never do that again.
LOL most probably not :^)
MikesRadioRepair Even here in the U.S. there are some higher powered HF radios and lower powered external amplifiers (say, 400-600W) that use a 24 to 28V, even 48/50V, external supply for their power amplifiers (the rest of the radio is often still operated from a 13.8V rail). The higher voltage both increases the linear range of the power transistors in the PA while also reducing the need for ultra-low impedances in the PA stage, and power delivery, to achieve the higher power output (consider how little impedance must exist to deliver 40-100 amps into a PA circuit, not just within the PA but also the wiring between the PA and power supply/battery) -- doubling the source voltage simplifies the design and power delivery versus 12-13.8V and allows for more reasonable wire gauges.
Just for curiosity what was the cost of the new board ??.............Ray H from the U.K.
Great video what did the board cost to replace ?
Yes I wonder too.. also the price for this board alone without working expenses.. curiosity will not kill the cat.
I too am curious of price of board, 73 KD9GRP
I also am curious as to the cost of the board.
I love these videos. Additional benefit is I get to pick up a bit of German from the instruments at the back!! Spannung == Voltage! Great work.
Question though - what is your thought on why the manufacturer doesn't put voltage protection on the input? Is it just a cost thing for them (as a commenter pointed out below) or is their some technical reason.
Thank you, glad that you liked it. Well regarding your question. I don't think that is a technical reson as it is no rocket science....I truly believe it is always cost reasons...73
Again another educating video, thank You!
Thank you Lars 73
Very interesting, Thank you Peter how much did the replacement board cost ?
Hi James it was a refurbished board done by myself it is half what the manufacturer is asking for it 73
Even if 24V ended up finally at the 7808 it wouldn't had blown it up; these typically have a voltage range up to 30 volts.
That is only valid if you have a huge heat-sink otherwise the voltage regulator can't stand it..73
WoW, you say right at the end that you do NOT want to drag it out too long, well I think that 47 minutes and 49 seconds is a bit too long, as at the end of the day, all you done was to replace a FULL NEW circuit board and NOT fix it as I thought that you would have done.
Also how did you know that after fitting the new board, that on one of the other boards that there was no problems that could affect the new board ???
I am not saying that what you had done was easy, as I know I struggled in fitting surface components, as even me using the larger resistors, I struggle with. I did find that using a set of reverse tension tweezers that can hold the component in place, is for me a God send. But this getting older and having a double cataract surgery a number of years ago, as just had a eye test on Saturday (14/9/23) and being told that between my eye and the plastic lens that they put in, it is starting to go cloudy ☹️ and they might have to do laser eye surgery, then perhaps my eyes might become a bit better.
But on the whole, good work.
Bye from Knobby.
Just had a thought, that voltage step dove converter, I do not know why Icom never fitted one that could handle at minimum 25v to 30v. As if the done that, they would NEVER have the problem of accidentally connecting to a 24v power source. As some trucks use 24v along with some busses/coaches and even some boats.
I know that the chance that someone uses 24v is not that common.
But as I say, I bet when manufacture of the radio, it would not add that much additional work and also would not add to the cost of the radio, as how much do them step down IC’s cost, and Icom would be able to get them at a massive discount to the price that you or I would have to pay.
Bye from Knobby.
really discouraged with icom. i literally order approx $22,000 a year in gear with the icom name on it ... i order from gigaparts which is excellent... one time i have a problem and icom will not stand behind it .. i order 2 icom 718 radios at a time, one time recently i get a case that is dented, " not the box the case" so i know it happened at icom , i do not blame it on gigaparts, there is no way it happened at gigaparts, it happened at the factory . was told i had to purchase a new case lid for $36.00 .. nice staff at icom but when it comes to customer service i am really truly disappointed. over not making it right they are willing to lose a customer that spends so much money on their product. .amazing......Attn icom. This will be posted in every area of the web i can find to copy and paste..
This customer took responsibility for their mistake and paid for the repair. Didn't complain to iCOM and threaten to lose their business unless they gave him something he didn't deserve. I'm going to buy an IC-7300 this year, and if god-forbid I dent the case, I'm going to pay the $36.00 for a new lid.
I had the same with Icom-UK. They are a waste of time. Brand new IC-9700 and an inductor went open after one week from new. It took my supplier to back me up before they would act under warranty. Icom tried to say it was my PSU that was not an Icom PSU (It is an Icom PSU), but I was mobile at the time running a straight 12V. They had no option but to fix it.
I was thinking it might be a good idea to add an anti-static pad to your work desk. Not only would it help with static discharge, but it would provide a slightly soft surface so as not to scratch cases when moving them and sliding them around the desk.
It is in any case important to have a ESD safe workspace and so is mine. The mat on the bench is completely ESD safe and connected to ground over 1MOhm. 73
thanks for reply but what is WEB 73????? pls tell me the link
After replacing the first chip coil you say "Ready to test" then jump to another toasted chip. I so much wanted to see the power-up procedure. Why did you not show that?
Hi, yes you are right that is always an exciting moment. I don't know how many videos you have seen from my collection but I have shown several time how I handle the ramp up. It is always a tightrope walk to decide what to show and what not as videos should really not get to long. And considering that my videos are always toooo long I decided to skip it here. Sorry hope you understand. Thanks for watching 73
Hello Sir,
My ICOM IC-706MK2 VFO encoder is faulty and the part has been discontinued..so u know which part for this replacement?
Has anyone had problems with IC 7100 Sound Card? ADC does not appear to be working on mines ... after using FT8 .. Any ideas?
24V mobile home? I don't know why new radios still don't use some zener or something to protect the input. I know the current is quite high and you'd have to do a purposely placed MOSFET shorting transistor but still what would this cost $2 extra for protection against this type of thing?
a common way to achieve overvoltage protection is a thyristor or transistor crowbar. It will blow the fuse in case of overvoltage by introducing a short in the supply line. It does not take a very beefy transistor or proper cooling as the shot circuit current flows for merely a few ms before the fuses blow.
I ärgere John today a Crow bar should be installed 73
With this auto type fuse. You'd need a clamp to withstand probably 200% of this www.littelfuse.com/~/media/automotive/catalogs/littelfuse_fuseology.pdf or 200A for 1 second. That's some serious power (2.5 kJ = 12.7V * 200A ) and PCB tracing! Even with 2oz foil that probably wouldn't work. This is good reason to NOT use less expensive auto fuse as it's more slow blow than fast acting. More appropriate would be fast acting and possible clamping method then. In looking at this that auto type fuse would protect the radio from almost nothing, weniger als nichts!
Ham4Ham Many radio manufacturers do include at least some degree of input protection, typically either a high power rated TVSS diode or crowbar circuit designed to try and clamp the input voltage long enough to blow the input fuse(s). These also can provide protection from polarity reversal faults. Such are typically connected directly across the input just inside the radio so that little, if any, current passes through the PCB foil as they are placed directly across the input leads and typically joined to them with a heavy blob of solder. I was a bit surprised that iCom does not appear to have done such in this radio as it does quite often work to protect the radio from catastrophic damage and usually only sets one back a couple dollars worth of parts (namely the TVSS diode and fuse) -- much better than having to replace a main or PA board just because of a moments carelessness.
Yes 24 Volt is a great possibility !! If that motor home is equipped with a diesel engine, it more than likely has a 24 volt starter to turn it over quicker / easier. I had a MACK truck that had the END 864 engine that's 864 cubic inches !! and the truck had 4 big 6 volt batteries ! 2 batteries in parallel on each side of frame with 4 wires going to a HUGE relay under the passenger seat to "WIRE the two sets of batteries in series for a 24 volt start then back to 12 volt run!!!! A complex setup, so I can see making everything 24 volt, it would make things simpler!!! John BellasKC2UVN.
Hi my real time clock battery backup on my IC7100 is not holding much charge anymore as it dies after a few days switched off. I was trying to see how easy it would be to swop and wanted to know is it soldered into place? I think it's near to the SD card slot. any chance you could have a quick look on the broken pcb and let me know. Thanks!
Hi, I'm Not in the lab for the Time bering. I will have a Look at the Weekend. If i forget it please remind me. 73
I can't believe you applied power after replacing the coil chip without checking for shorts first. mistake
damn producers why dont put a simple over voltage protector in these expensive radios :/
Peter now I relook and see radio supply has 30A fuse. Why would this be? This seems crazy? You could have 5kJ (5kw) inside the radio momentarily during fault conditions. I am curious on peak current measurement for 100W radio with maybe 25 ohm load over 10mS. Because RMS should still always be ~100W maximum which would only be near 8A. This seems could even be fire risk potentially from being such a wrong size.
Ham4Ham While 30A is a little high (most 100W HF radios will use 25A fuses), one must keep in mind that a 100W HF radio will draw around 21-23A during transmit at full power, particularly in FM and digital data modes. That peak operating amperage really sets a hard limit on how small a fuse value can be used since such current levels can be sustained for minutes at a time when operating in certain modes, plenty of time to regularly blow an undersized fuse. For this reason most 100W HF radios will be fused at around 25A. However, many radios will also include a TVSS diode or crowbar protection circuit on their input designed to help protect the electronics by reducing let through voltage by placing a near dead short on the input allowing the fuse to quickly blow. Such can also provides a good level of protection against polarity reversal. Such protection circuits help to reduce the risk of catastrophic faults by limiting damage in many cases to just a few dollars in replacement components (namely the TVSS diode and fuse(s)).
I am uncertain where you are getting your 5KW figure for a 30A fuse at 13.8VDC +/-15% ( ~414W), unless you are trying to figure peak let through in the moment before a fuse blows (but such is a rather pointless spec as it is time weighted and one seldom knows the system fault impedance and duration time ahead of time, after all, if not for some resistance, a fuse will allow infinite let through wattage for an infinitely short duration before it blows).
RF output part of radio is only 30% efficient? Needing nearly 300W input to output 100W RMS? I never actually measured mine to see. 5kW would be near a 1 ms fault from the I^2T. Power supply couldn't do this, but car battery could. So filter suggests by 30A size burns enough over 22A for a 25A to not work.
+Ham4Ham Hi John , yes the efficency is really quit low. 73
ANOTHER JOB WELL DONE. SOMETIMES YOU JUST HAVE TO BITE THE BULLET. AT LEAST THE PARTS ARE AVAILABLE.
LOL yeah :>) Thanks for watching 73
Good decision to replace the main board.
Peter tnx, great Job, 73 Peter
Thanks for watching 73
Hi Peter, as always great video, even if have not been able to fix it by changing some little components (it's the 1st video of this kind isn't it?) But if it is toasted too much, even the "wizard" has no chance ;) 73's
LOL yeah that' it. Well to be serios you always have to have the costs for the om in view so there is a Point wehre you have to Go another way. Personals I would Love to See what the Problem was. 73
Excellent video as always Peter. I always learn something from listening to your methodical approach to troubleshooting and this video is no different. Great job.
Out of curiosity, what was the cost of that replacement board?? That radio retails for nearly $1000 here in the US.
73 de N0BPS
Thank you Brian! I don't have the invoice yet but I think around 400 bucks 73
TRX Bench Ouch! That is a lot of pain for a few seconds, and a very human, act of momentary carelessness! My heart really goes out to him as I have had to repair my radios as well after a power supply fault allowed the unregulated rail (about 20-24V) through to my radios. No matter how many electronics I have repaired over the years, my heart still sinks whenever I see that magic smoke (they really ought to sell refills of magic smoke).
This case is a good argument for using Powerpole connectors with different keying for your 12V and 24/28V power supplies so that they may never be attached to the wrong supply. I use them extensively for my gear as they really go a long ways to reducing accidents when connecting and disconnecting equipment (especially the dreaded polarity reversal). We all make dumb mistakes every now and then no matter how careful our personality.
Surprising it isn't more. If that were a Kenwood it would probably be over $1200.
What sad moments...maybe a little varistor as power supply protection, could save or reduce risk for that kind of radio. Have you used one for the 2nd new icom board !? By the way..what do you think, why icom or other usually not used a cheap overvoltage protection ?! '73 :)
Hi Alessandro, well it is all about money. A nice crowbar would help. Thank for watching. 73
Are you going to post any videos of the 7300?
Ron, what do you mean??
how much did that new board cost ?
Icom should have installed a 12/24 voltage ragulator at the power input with a reverse polarity protection
Yeah would be a good idea but to expensive for the bean counters :-)
or atleast regulatorchip that have a 27V at maximum input....instead ov 20V.. little difference at coast at componentlevel but i think costumers will accsept to pay a little more for a radio thats protected for voltages up to 28V
Hey I really like your videos and I'm a subscriber also. My question is where do you get the schematics.
I get my schemas over google search..73
Don't forget to order the previous IC as well you used your last one in this repair
Where was the Fuse ?
This ICOM 7100 was only made to work by board swapping, The faults were NOT repaired on this PCB !!
one of the feet is missing in the front. Why not design a rotating and flip the radio over in the form of a frame that holds the radio and suspends it on the workbench?
WERE DID YOU GET THE schematic diagram LET ME KNOW PLS
Most are available on the web. 73
Vc teria um contato???
Hi sir, I am your avid follower, may I know how/where do you order the PCB? thanks..
What PCB do you mean? I swapped out parts only...