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- Опубліковано 9 гру 2017
- In this video we Look at another IC-745. We find several problems and we discuss the ram board programming
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Discuss this on my website; I am posting files and diagrams on programming.
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Great video as always :). RX cutting out at the beginning was likely due to the squelch setting. I can see that it was too high.
No need to apologize for anything Buddy. We all know that your time must be extremely limited due to the number of repairs, your day job, your house and shop projects not to mention the time it takes to shoot, edit and post your videos. Then there are the emails, video comments, ordering parts, computer research etc. To be honest, I don’t know how you get it all done. But I sure am glad that you allow us to watch you do your repairs. Thanks again
Great video on the brain of the IC 745. I remember in the old days a bypass technique was used to keep the memory alive with the root operating system, while a new battery was connected in parallel and then the old battery was removed. The worry then was Icom would not support the product after a few years and the radio would become like you said, a brick.
Those guys who came up with a non volatile plug in board for these radios did a great service for the ham community.
I bought my 745 in '83 and I remember I also paid 745 dollars for it. The dealer even included the sales tax in the price. The only negative comment I can make about the unit is between 800 and 900 kc on the broadcast band it had display noise messing with weak signals. Other than that it was a great radio and I loaded it up with all the options after I got it.
Glad to see they are still around.
They're about 39 years old have one and still use it, great radio
You've produced another great video Buddy. Apart from the excellent description of the repair itself, I also love the hints and tips you have included on related issues. Thanks a lot.
Thanks for the very nice comment. Most appreciated.
Loved the video as usual! Buddy, you're the Maestro of ham radio repair! I like the way you verbalize your thought processes and tips and go about your work calmly. Please continue your videos on the IC-745 and the whole line of Icom transceivers and receivers. Not only are your videos so informative but they are great resource references for the future. Happy Holidays! 73's, Dr. Stan, KZ8G.
Thanks Dr Stan for those kind words. These are the type of comments that keep me going. Many more to come on the Icom products. Happy Holiday to you my friend. 73
Buddy, thank you for your time and sharing with us. Yet another piece of vintage gear saved. Thank you for your instruction and expertise. You da man. Joel
Thanks Joel. Glad it is useful information. Have a great holiday my friend.
Wow, that radio is way too complex for an old phart like myself to work on. I really enjoyed watching you work on it. Great job Buddy. Thank you for sharing it with us.
Good video! I still have my icom 735 that I purchased in 1992! Hot receiver!
Great video Buddy, Buddy. A little more complex today. WOW You really get in there to the Nitty Gritty and it gets fixed right. Thank you for another super interesting video....Angelo.
Thanks Angelo. Glad you liked the video. I love the old Icom 745 rids, fun to work on and have repaired quite a few of them.
It looks like you are quite popu;ar this week with the Icoms The RAM module is a great idea so you don't end up with a great light boat anchor. Keep up the great work.
Nice repair as usual big thumbs up buddy
Great informative video as usual. I have two working 745's and three IC-AT500 auto tuners two of which had issues. You did not elaborate on what the problem was with the AT100 but I thought I mention what I found with two of my AT500's. Icom used a very stiff wire as the lead from the matching network inductor to the L selector switch. In two of my AT500's, the solder was cracked or completely separated from the switch's wafer connection. The stiff wire apparently stressed the solder joint to the point of failure. Once I repaired those joints, both tuners worked as intended. K1NVY
Excellent vid.... I learned a lot thanks bud.
Great video! Thanks!
Very good repair video, Like these Thanks Buddy
Thanks Dennis.
Good job, Buddy! Got it working nicely. 73...Dan w4mnc
Appreciate it Dan.
Great video Buddy! It seems you have a lot to do :^)...Take care my friend
Thanks Peter. yes so many rigs and projects here. I need a clone!. Take care my friend 73
You can run DOSBOX I use it to program old Kenwood business band radios. usb to parallel port adapters are around.
That is interesting. I was told by others that Dosbox did not support parallels ports.
We need to get Mark to come up with a program to be able to interface to the board with a modern computer using a USB cord to copy and write the program to the EPROM's. Next time I talk to him I will ask him if he has any ideas. Mike
I bet Mark has the answer. Point him here :)
Easiest way to interface to a board like that would be with an arduino, which would be compatible with 5v logic. Depending on the actual size of the ram module, it would even be possible to create a stand-alone programmer.
Yes, of course, that would be the fast, ease and reliable method without the need of the frequently out-dating "Fuzzy PC SW parallel port solutions.
I have an ic 745 that was re done a couple years ago have not been using. hooked up and it won,t change from lsb, usb, and other frq, am ect.battery is good.Don,t know if i want to fix now. but was working till put on shelf. thanks
Nice jobs, again. I love these videos. QUESTION: It seems like we see a lot of ICOMs on the bench being repaired and in some cases, fix for a ICOM induced issue. Are ICOMs more prone to design issues or age related repairs that the other majors vendors?
Thanks again.
" Are Icoms more prone to design issues or age related repairs than the other major vendors?".
This question should be an entire thread/forum in itself. This would be a super discussion for collectors and those of us who are still learning.
I need a step by step simplified way to perform the latest agc mod to this rig. Does anyone have instructions that are simpler and better than the long winded discussion of what went wrong and what can be fixed but does not say change this or replace that which is what I need to do the mod.
hi hi. im restoring an icom r70 receiver and its also got the plastic trimmers. where do you order your icom parts from? ive looked up icom parts and i cant seem to make any real headway. the trimmers seem smaller on the rc70 but im assuming they are the same size. i found a similar one at jameco electronics and its a 9-50 pf range and im not sure if that will work or not? the other ones seem a different form factor. thanks!
I have a 740 the auto keyer isn't working any thoughts?
Does the RAM Board come pre loaded or do I have to program them some way. My IC 745 is receiving fine but the big problem is severe drift. I think I will try to replace the caps and ground the xtal for starters. Other than the drift I love this radio. After 53 years on the air and loads of tube work this will be my first attempt to fix a “modern rig”. 😩
This sounds like the VCO trimmers are faulty. If you look back at previous videos I show how to replace these.
Hi Mr. I'm from Argentina and I've a 745 working good, anyway I wonder where can I get one of those eprom memory cards. Do you have one mail or something to write on?
Really enjoy the ic-745 videos. Do you need one more to work on? 😁
Thanks James. Do you have one with a problem??
Yes, I have one with very low RF output (less than 10 watts). PA seems to all be OK, but not getting much drive from RF unit. I do not have a good way of measuring exactly how much drive. I'm not sure if it is actually low coming out of the RF unit or if it is being lost in the filters. Receive is working perfectly. It has been a few days since I looked at it. Any ideas on what to look for?
Your really good with that hook. You should have been a dentist.
Thanks, but do not think you would want me working on your teeth lol
You can still buy parallel ports for modern computers. I don't see why you need to use USB...
How do I contact you? I have a 745 that's non functioning that needs looked at.
Could you just remove the eprom from the replacement ram board and read that instead?
The replacement ram boards are ROM not ram. Like the PIEXX board. And is an eprom. The original boards are not eprom. They are flashed DRAM. So totally different units. You cannot remove the prom from the original either due to it's content is held there by a battery.
The Radio Shop I thought that the PIEXX Eprom would hold a copy of the factory data so would easily be read by any eprom programmer. It would certainly be easier than trying to read the dram on the original board as the designers of the PIEXX board have already done it for you and stored it in the eprom.
Oh I see now. I have yet to see anyone try and read the data on the PIEXX board. I was told it was protected so it could not be read. Anyway the format on the PIEXX board is different than the dram. Good thing is there was already copies of the original files posted on the internet. I had the copies for years, just no way to program it back to the old board until now.
I noticed the new Ramboard has a GAL on it so maybe the data stored on the eprom is encrypted or the GAL is simply used for address decoding?
The Radio Shop You answered my question as we crossed replies. I can understand you wanting to program the original board after changing out the battery. Makes sense.
And why would they use plastic trimmer caps in such an expensive radio when ceramic ones are superior?
Two words. "Bean counters" Yep they went with a cheap trimmer where they save a few pennies on production cost.
plastic trimmers have a better thermal coefficient, better stability in time. Of course, the plastic rots after 25 years, and problems start to appear. Ceramic caps are OK, but they must be thermally compensated with a parallel, fixed value capacitor.
start the IC745 with a known good RAM module. in the meantime, change the battery on the dead module. Now, remove the good RAM module from the transceiver, WHILE it's up and running. Put the dead RAM module in it, change the frequency a few times and the bands. Turn off the transceiver. Turn it back on, and the dead RAM module should be OK and programmed now.
That is very interesting information. Have you tried this? As you are the first person I ever seen mention this. Details please.
the CPU reads the data from the RAM at power on, and writes the data in the RAM when it's powering off, or band change, or frequency change. When you're swapping the RAM module, make sure you don't touch the VFO knob. I did this many times recovering swappable faulty computer BIOS-es. It's the same principle.
The problem is that the interface between radio and the ram module is not designed for hot plug operation. Means that plug in -out "under fire" can easy destroy mainboard, ram module or both. The second is that the basic configuration data will not be written back. It writes back only frequency sets from the user. The basic configuration setup remains in the RAM module for read operation but will not be rewritten back in the blank module.
You Sir are very correct. I only did this to satisfy a few folks using my own rig, Lucky no damage was done. We are moving towards Arduino for the programming platform. At the same time I am reviving the N2CBU programmer since I have an older computer here to experiment with. Thanks for contributing your knowledge on this. Would love to hear more if available.
It seems like an Arduino would be able to read that board. No need to convert to USB.
That is correct. We are working on that now.
So I get the impression I should not ever get a used 745
Yes do. Just rebuild it and it will be great
Hi Buddy,
Nice repair and video. Guess you will be busy for a while. HiHi
Have you lost any patrons due to the new Patreon fee policy? 73 WB3BJU
Buddy where can I get the trimmers. My mint 751A has just failed with this issue but Icom do not keep the trimmers anymore. Will another trimmers do as a replacement 😮😮