measure the same points in reverse as there is a diode in the circuit which maybe impacting measurements.... maybe. It doesn't look good for the IC based on some of your work to date. But possibly do some more resistance check comparison between the working board and non-working. This may give you some further pointers to either the IC or supporting / connnected circuit component issues.
Good progress anyway I think. I was mainly asking for resistance on pin 2 to see if there was a short in the circuit on the output side of the ic dropping the output down. Doesn't seem to be shorted as the 8v you supplied remained, though there is a difference in the resistance reading. I guess you could confirm if it's the ic or not by swapping them between the boards. Resistance readings on all the pins might give some direction too. If you do remove the ics take readings on pads while ics are off. Also a bit of freeze spray may just kick the bad ic into action - maybe try that first. Just throwing out ideas.
Good progress anyway I think. I was mainly asking for resistance on pin 2 to see if there was a short in the circuit on the output side of the ic dropping the output down. Doesn't seem to be shorted as the 8v you supplied remained, though there is a difference in the resistance reading. I guess you could confirm if it's the ic or not by swapping them between the boards. Resistance readings on all the pins might give some direction too. If you do remove the ics take readings on pads while ics are off. Also a bit of freeze spray may just kick the bad ic into action - maybe try that first. Just throwing out ideas.
I like the idea of "swapping IC" IF you are good at desoldering / soldering packages. It could an "easy" way out.... or not :-)
I dont mind to try desoldering/soldering the IC. However I'd like to find and order a backup one or 2 just in case and then try while the backup ones are on the way here.
The problem is I cant find anywhere to order the things to send to Australia
but as suggested, do the "comparison resistive" measurement around the chip. This may give you an idea if the chip is indeed the culprit or a supporting circuit component is fried. The "re-chip" is somewhat of a "last resort".
No manuals will make it hard but essentially if you think of the board as a processor then the only difference between any model is the firmware , data, program loaded on non volatile memory.
some of it is common. So either desolder and swapover or copy the data and overwrite the chips but you'd need a clip.
I've had some fun with a CH341 but the clips supplied are rubbish
Hey do you have a guide to the CH341? I bought one recently and figured I might as well have a play around while I'm waiting for parts
If you're playing with the A boards, copy and save the original contents , label so it can't get mixed up. Pay attention to whether it's a 24 or 25 series chip as the pinouts are different and how you set up the the CH341A too.
If it's wrong you'll see the led go dim, things get hot and then some of that smoky stuff starts to release.
I know the original clip and cable was rubbish, broke after a few uses,
If you're playing with the A boards, copy and save the original contents , label so it can't get mixed up. Pay attention to whether it's a 24 or 25 series chip as the pinouts are different and how you set up the the CH341A too.
If it's wrong you'll see the led go dim, things get hot and then some of that smoky stuff starts to release.
I know the original clip and cable was rubbish, broke after a few uses,
I was going to see if I could just download the eeprom from the A board just in case.
So did you get a clip with yours to clip onto the chip while its still soldered on the board?
Otherwise mine must have been too cheap and missed the whole clip idea...
I was going to see if I could just download the eeprom from the A board just in case.
So did you get a clip with yours to clip onto the chip while its still soldered on the board?
Otherwise mine must have been too cheap and missed the whole clip idea...
yeah , came with a clip although it broke and now I can read, but not program so I just take the chip off and solder it onto the board that came with it.
So far I've fixed a corrupted eeprom with it and done a conversion on a new zealand board. Kinda fun transferring the DNA across.
3M and Pomona are 2 brands for those clips. Not cheap, I'll get one one day
Well I have an update.
The replacement IC's came in. I soldered the chip in and turned the TV on. It worked!. I checked output voltage from the IC it was 8.5V. Then I turned the TV off.... and tried to turn it back on again. The relay clicked to turn on and then the TV turned off with the same blink code again. Bugger...
The other symptom is the IC does get hot while the TV is on.
Since I've tested most other parts in circuit I feel I'm chasing my tail.
I've done a non normal fix I guess and used a 5v relay to trigger when the 3.3V panel on comes through. This triggers a separate adjustable output voltage regulator which is powered by the 15V and changes it to the required 8V and feeds that back into the circuit.
The long and short of it is that this seems to work but theres obviously some other part in circuit thats not performing correctly. I've had the TV on for an hour and nothing seems to be getting hot.
If it dies I'll just have to get another board.
Thanks very much for the help in finding the faulty area!
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