I'd guess the TV main board is bad. What are your thoughts on this?
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- Опубліковано 5 лип 2023
- One thing I never liked about troubleshooting a television problem, is the guesswork involved in figuring out why the TV isn't working. Having a schematic, and a basic understanding of how your TV works reduces the chances of a misdiagnosis, but if you don't have a schematic, there's always a certain level of guess work. On this Television I'm guessing the main board is bad, but unless the customer agrees to have me fix it, It's going to remain a guess. What are you thoughts on my diagnosis here?
This Television is philips, but the back sticker says it's a Funai TV. Model number 50pfl5766/F7
I worked as a IT technician, and experienced lots of problems with laptop and desktop mainboards that whent bad due broken solderjoints under the chipset and VGA chips.
Since arround 2006, manufacturers of electronic devices may not use lead based solder, and start to use lead free solder,
but lead free solderjoints become brittle after a certain amount of heat cycles.
Lead was added back in the days not only to lower the meltingpoint of the solder, but for the main reason to prevent socalled "Tin Whiskers".
Tin Whiskers is like a conductive mold that grows between leads of components and cause all kinds of shorts.
I encountered many mainboards of laptops and desktop computers that suddenly start to failed near the end of the warranty period, or just after the warranty period expired.
I first tried to heat all big chips on the mainboards with a professional hair dryer (110° C),and after heating up for a few minutes, i let the board completely cool down.
With this trick i could revive many mainboards back to life. Soms kept working for years, while some encountered the same sympthoms (no screen output) after a few days or weeks, or sometimes after a few reboots.
At that time, i didn't have a hot air soldering station to heat the chips even further, because solder don't melt at 110° C, so i start using a heatgun for stripping paint at the lowest setting, and used tin foil to cover electrolytic caps and plastic parts on the mainboard, and cut a window open arround the big chips. With that method i reached a higher succes rate, and if the mainboards survived a few reboots, i was almost sure that the problem was solved for a long time. Eventually some came back after many years, and some kept working for years. So my guess is, that every device that has a mainboard, like a TV, can have this same issue. So my advise is, try to heat all the big chips, let it completely cool down, do not force the cooling down with compressed air, because that can cause the solderjoints to crack again. Grtz
Thanks for sharing your experience with heating up some of the main board chips. I remember reading about tin whiskers that grow on solder a few years ago. I didn't realize it was more of a problem with the led free solder
@@GrantsPassTVRepair , without the lead in the solder since arround 2006, the problem with tin whiskers is back. And one of the biggest problems with tin whiskers, is that these act as very tiny fuses, if they are between 2 points on a board that carry a very low current, like signal lines, they shortout the signal. But when they occur between 2 points of let say a voltage rail and ground, they burn up and remove the "evidence" of the fault. But those little shorts on powerrails clean themself up, but the bigger problem is on data lines. So a cleanup with iso propanol and a tooth brush can solve that. It's like placing steel wool on a 9V battery it will burn itself away, but when the battery is almost flat, nothing will happen and the battery gets drained to zero volt. But these tin whiskers are not the biggest problem, it's the brittle solderjoints beneath big chips, especially on chips that heat up during use. Back in the day when i revived a mainboard by heating a chip, i placed also a tin sheet of copper between the heatsink and chip, or a bigger heatsink to keep the temperature down. Some boards like in a tv can become hot, and don't have a heatsink, so those are the primair suspects for this solderjoint issue.
When i make electronic projects , i always use lead based solder, now these days, this lead based solder is not sold everwhere, some part suppliers only have lead free solder, but i found a supplier here in Belgium that still sell lead based solder from the Stannol brand and i have and hoarded some stock, should this ever go out of sale to the wider public. It is still available only for professional users, and is still used in military (and some medical equipment) for a higher reliability.
@@BjornV78 I remember seeing this video by Louis Rossmann where he talked about re-balling solder connections, and his conclusion on it's value Vs just applying heat as you mentioned. Here is the link. ua-cam.com/video/1AcEt073Uds/v-deo.html
@@GrantsPassTVRepair , At that time (2007 a 2008) when I start using this heat trick, I told the customer in advance that there was no guarantee, and that the problem could come back at any time. And that with laptops that were regularly made dust-free, so that the laptop remained cooler, the problem will remained gone for a longer period of time. This was therefore one of the repairs for which I could not offer a guarantee, and so I did not charge the customer too much. But at time, this first start occuring on HP Pavilion 17" DV9000 series laptops, that cost arround 1600€ (almost same price in $) and that whent just out of warranty. So if i offered the customer a choice of a "fix" without warranty for 50€, or a new laptop at 1600€, almost everyone choose for the "fix". And if the laptop failed again within a week, and they bought a new one, i gave them a discount for the trust in my business.
Every non tech guy thinks its the fuse that's blown. I like the audio oscilloscope idea.
Try the easiest thing first.
Lol I work on cars for a living and its the same thing with that too
Handy hints there, thank you. I'm trying to fix my old Toshiba 40 inch TV. Newer TV's don't have all the inputs I need, they have 2-3 HDMI ports and maybe a composite. I need at least 2 SCART sockets, 3 HDMI, 2 Composite inputs and VGA for the computer.
I looked at more modern TV's with only HDMI, they were around the £150 - £200 range. I found another Toshiba with only 1/2 the inputs but it did have VGA. It cost me £380.
Your "audio oscilloscope" is a really clever idea. I'm thinking about modifying it so that the indication is a LED which glows more brightly as the signal gets stronger. BTW, I'm the person who designed the Anatek Blue ESR meters...
Nice to meet you Bob. I built one of the blue ring testers kits you invented, and appreciate it's clever little compact design. I've experimented with variations of near field inductive probes, and noticed there are already inexpensive inductive probes with LEDs available for testing 120 volt mains, but I've never seen one specifically designed for testing small boost and buck coils, so it sounds like a good idea. One of my probes has an internal diode to rectify the electromagnetic oscillations, which I attach to my DC volt meter for more precise indications, but an LED light indicator, or even a built in audio amp could be handy. Especially if it had a sensitivity adjustment. Dave
@@GrantsPassTVRepair Hi Dave. Right now I've got a PC power supply apart for replacing a lot of old electrolytic caps. Once I've done that, I'll do some experimenting with small RF chokes like yours to see if a simple circuit would do what's required. I have to be honest that it was the late John Bachman at Anatek who created his Blue version of the ring tester I originally designed way back in the 1990s.
@@ZilogBob I remember seeing analog ring testers for TVs long before the digital versions were available. 8 years ago I made a video about your ring tester, and how useful they can be at this link. ua-cam.com/video/Ky2T1-n_Fks/v-deo.html
@@GrantsPassTVRepair A while ago I designed another ring tester which can count up to 99 rings. I've got all the info about it on my website. Right now I'm trying out a little 2 transistor circuit based on your "sniffer" which makes a LED glow in proportion to how strong the signals induced into the small RF choke are.
I would tend to agree with you Dave as my 32 inch Vizio TV I had in my bedroom died a couple of years ago after about 12 years of use. I bought a new Vizio 32 inch for about $200.00, and it's 1080 instead of 720, and it's also a smart TV. I suspected the T-con board was bad in my old TV, and replaced it for $10.00 and tax from eBay. That fixed it, but it now resides in my closet. God Bless Dave.
Considering the low cost of replacement, It's no mystery why so many repair shops have closed their doors. I'm grateful to remain afloat doing antennas, and a variety of other TV related jobs.
@@GrantsPassTVRepair a possible somewhat reviving area of CRT repair is for vintage video game consoles/computers like Amiga, Atari, Nintendo and even older PC. The purists want the original CRT for authenticity and better game play.
I found a couple of these branded CRTs, 1084 and 1701, in thrift stores, refurbished and sold on Ebay for a decent profit.
Odd I know...but collectors, go figure.
@@pvb9964 I run in to people who want the CRT TVs now and then for the reasons you mention.
the small amplifier that you got to pick up the noise is very useful.
The audio tester for inductors looks super handy! Something I'd love to build and add to my tool set. Is there a limit of frequencies it picks up to make them audible? Unless it's your own unique invention, could you share what exactly is inside the probe at the tip? Maybe make a video on that tool? This reminds me of ESR cap checkers, which are super handy but have always been cheaper to build than to buy.
Anything outside the audio range of the human ear can not be heard with this audio pickup device, Sometimes I attach a volt meter to the end of my probe that measures voltages which can't be heard with my ear. I will keep your suggestion in mind for a future video.
I think a little differently than someone in business who has to take the economics into account. Just can't stand to see anything "not fixed" and ready to be in service. Also, hate seeing landfills grow. So, I fix 'em anyway ... and look for a good home. Thx for your vids.
PS: Like your component "listener".
I feel the same way about throwing TVs away, but it boils down to financial economics.
I'd be very interested in seeing a video on your audio tester. How it works and how to make one. That seems like a great tool to have.
They are really simple to make. It's just an audio amplifier attached to a small coil. Much like hooking a microphone to an amplifier.
@@GrantsPassTVRepair Thanks, Once I thought about it for a second I got it pretty quick. Btw, I've been checking out some of your older videos today and there are quite good. Thanks again.
Thanks, all the best,
@@johncrab67
The big inductor over by the tv screen ribbon cable did not seem to be doing anything. Makes me wonder if there is a short on the screen. None the less, you could chase that for hours. Even when you want to quit, it sucks you back in. lol. Good for clipping a few parts out of, and to the dumpster if you can't find the problem easily.
I’d love to build a replica of your audio-tester. Have you posted a schematic somewhere? Looks simple and practical. Cheers!
The small amplifier I have was probably purchased at a garage sale. They were commonly used to amplify telephone calls, and they came with a suction cup attached to a coil which was used to attach the listening part of your phone.
Hello dave, did you try to flash the firmware of the NVram or cmos?
Can I get some specs on the audio oscilloscope please 🥺
I spent $100 on boards I bought off Ebay for the same issue, no go. I've wonered if this is a sleep mode issue where the TV won't wake back up, like the desktop PC issue of the 90's...a huge problem. Some TVs have a reset-to-factory option in a service mode, if you can find it. Btw, the no-wakeup problem was defective caps on the PCs.
Unlike my computer monitor, I've never seen a sleep mode for a television, but I appreciate your input.
@@GrantsPassTVRepair ...it's a feature of FireTVs for example.
@@edzanjero353 I don't understand what you are saying. Can you clarify your comment?
@@GrantsPassTVRepair ...at least on FireTVs, depressing the power button, or using the remote on-off only puts the TV into a sleep mode...but the TV is actually on. To actually "turn off" a FireTV, you have to pull the power plug. Also, to reset to factory defaults on a "no power-no display" symptom, some brands have particular button depressing procedure upon powerup to get into service mode, so you can view and select a factory reset. Some units will perform the reset with no video.
@@edzanjero353 I think ROKU dongles also remain on when the TV is turned off. That's why I prefer to plug the dongles into the TVs own USB port if the TVs power supply can handle the extra demand.