sanyo clt2054 intermittent grainy image

[cadillacman]

i will try to get a pic of thos issue but dont know if i will be able to catch it.

THis is a set i took in on trade twoards a larger set i had. Supposedly worked perfect.


well after failing a burn test after only about 20 mins im not too happy.

Ive tried different cables and different video sources, and this issue happens wether im using yellow composite video or red green and blue component video inputs.

Sometimes the set looks great, other times the screen gets alot of horizontal lines/noise kinda like red sparklies like you would see on a bad plasma almost. this is an lcd though. basically it looks as if i have a bad video cable or something, but i do not.

Sounds like bad panel to me but im still going to tear it apart and make sure i dont have bad caps or a loose tcon cable or something. BTW this has an external 12v supply, is it possible its got ripple and causing my issue.

Man i have just about lost faith in the general publc around here. Everytime i do a tradeup deal i end up with all junk..


THis is the second time ive gotten a set that worked perfect for a little bit then puked. It was a different dude this time but i swear, mabye hes family. i just wonder wtf they do to make them for for that short ammount of time. Put em in the refrigerator mabye?

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

heres some pics. Ive shotgunned a couple caps, 2 on the inverter has too much ripple, one on the mainboard looked slightly domed. Of course those didnt fix a thing.


the weired part about this is all osds look perfect, remove input then the screen looks perfect as well. wish i had an alternate means to drive the panel to make suire thats not my issue.

[PlainBill]

Re: sanyo clt2054 intermittent grainy image

heres some pics. Ive shotgunned a couple caps, 2 on the inverter has too much ripple, one on the mainboard looked slightly domed. Of course those didnt fix a thing.


the weired part about this is all osds look perfect, remove input then the screen looks perfect as well. wish i had an alternate means to drive the panel to make suire thats not my issue.

OK, if the OSD looks perfect, and the rest of the screen looks perfect if no input is present, the problem is in the input signal processing area. Have you checked operation with either digital OTA or HDMI signals?

PlainBill

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

OK, if the OSD looks perfect, and the rest of the screen looks perfect if no input is present, the problem is in the input signal processing area. Have you checked operation with either digital OTA or HDMI signals?

PlainBill

does not have hdmi, its a old turd. i think its got s video i could try that but i dont thin s video is digitsl is it?

[PlainBill]

Re: sanyo clt2054 intermittent grainy image

does not have hdmi, its a old turd. i think its got s video i could try that but i dont thin s video is digitsl is it?

No, it isn't. Does it have a DVI connector?

PlainBill

[jsog]

Re: sanyo clt2054 intermittent grainy image

What's with the strange black paint cracking on the 470uF SMD caps? Every one of them has it, none of the other values do. Maybe from heating and the sleeve moving under the ink/paint.
Prime suspects if you have an ESR meter.

That replacement cap on the signal board is 85 degrees and looks off-brand.

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

yeha i know its a pos just trying to isolate my issue here..

set does not have dvi. it does have regular cable im going to give that a try tonight

[lakeman]

Re: sanyo clt2054 intermittent grainy image

i have repaired several of these tvs. the most common problem is bad caps inside of the power supply module you can break it open on the seam or go on ebay and pick one 20 to 30 dollars

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

hmm... i did not see any ripple on my meter, but no prob i hsve a big 12v power supply i used to use when i fixed car amps with a big a$$ capacitor on it as well.. i will test with alrernate power and post my results. If thats all it is i will be a very happy camper.


edit: tested with two different known good 12v power sources, same result.

this is in the set someplace.... black screen looks perfect, try to display some inpoutted video thats when it all goes to krap. osd looks perfect and rock solid.

[PlainBill]

Re: sanyo clt2054 intermittent grainy image

hmm... i did not see any ripple on my meter, but no prob i hsve a big 12v power supply i used to use when i fixed car amps with a big a$$ capacitor on it as well.. i will test with alrernate power and post my results. If thats all it is i will be a very happy camper.


edit: tested with two different known good 12v power sources, same result.

this is in the set someplace.... black screen looks perfect, try to display some inpoutted video thats when it all goes to krap. osd looks perfect and rock solid.

I'm channeling wizard at this point. Noisy LDO regulator feeding the input section. The clue is OSD is perfect.

PlainBill

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

sweet... i like your train of thought...

want some closeups bill to point me in the right direction?

i really got rammed on this trade deal, would be ecstatic if i could fix this thing.

btw, if you want the power supply from that coby tv to play with bill, shoot me your address and i will send it to you.

[PlainBill]

Re: sanyo clt2054 intermittent grainy image

sweet... i like your train of thought...

want some closeups bill to point me in the right direction?

i really got rammed on this trade deal, would be ecstatic if i could fix this thing.

btw, if you want the power supply from that coby tv to play with bill, shoot me your address and i will send it to you.

I'll circle some regulators on some closeups, but I don't even want to think about the power supply this week.

Do you remember Prince Humperdinck's line from 'The Princess Bride'?

"Tyrone, you know how much I love watching you work, but I've got my country's 500th anniversary to plan, my wedding to arrange, my wife to murder and Guilder to frame for it; I'm swamped. "

He has it easy.

PlainBill

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

i mean , ideally, i shouldnt be seeing any ac on this thing right?

one smd ic marked as a diode im getting like 0.100 vac on the tab, seems kinda sketch to me but then again i am an idiot. I marvel at you guys who can just look at this and go oh heres the processing ic, heres the regulator, etc it amazes me.


edit: heres some pics... get this: after poking around every suspect ic checking +5 and +3.3 etc, now i have a good image again...

mabye cold solder on one of these regulators?????????????

there was barely any solder on the legs of these things.

i went ahead and reflowed them all. My slight remining noise shown in the pic below is gone, pic is perfect. No ammount of flexing or tapping will make this former issue reappear.

I will run this set a couple hours tommorow then put it back togther to make sure, but again thanks to bill, i believe we have found this issue.

[PlainBill]

Re: sanyo clt2054 intermittent grainy image

i mean , ideally, i shouldnt be seeing any ac on this thing right?

one smd ic marked as a diode im getting like 0.100 vac on the tab, seems kinda sketch to me but then again i am an idiot. I marvel at you guys who can just look at this and go oh heres the processing ic, heres the regulator, etc it amazes me.


edit: heres some pics... get this: after poking around every suspect ic checking +5 and +3.3 etc, now i have a good image again...

mabye cold solder on one of these regulators?????????????

there was barely any solder on the legs of these things.

i went ahead and reflowed them all. My slight remining noise shown in the pic below is gone, pic is perfect. No ammount of flexing or tapping will make this former issue reappear.

I will run this set a couple hours tommorow then put it back togther to make sure, but again thanks to bill, i believe we have found this issue.

One of my stints was in a company that produced a line of automation control systems. Of course, we also produced the boards to interface our hardware to a number of mini computers. Some of the boards were quite large - 15" x 15" with 50+ ICs was not unheard of. Testing these was a real bear - we used a semi-automated system that tested all the logic gates. Failures were troubleshot with a probe that indicate pulse activity. You HOPED to find a dead node so you could trace back from there. Standard procedure was if the tech doing the testing hit a failure they couldn't solve in 20 minutes, they should call on me.

One day one of the most complex board was giving a tech fits. After half an hour he came to me for help. After another half hour I went to the test engineer - who was swamped. An hour later, 'John' comes out to the test area, looks at the board from about 4 feet away, grabs a pair of cutters, snips one leg of a ceramic cap and said 'There was a cap in the wrong hole.'

Compared to 'John' on his worst day, I was a rank amateur on my best day.

PlainBill

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

thats crazy man.. i guess as far as my day job goes working on cars, i guess im up to plainbill level for auto repair..

your frickin awesome bill. DOnt you dare go anywhere on ue here anytime soon.

[cadillacman]

Re: sanyo clt2054 intermittent grainy image

been up and running, survived a 24hr burn in and several power on for an hour tests. im gonna call it good. I will update if anything changes.

thanks again to everybody here really. Its an awesome thing when we can all throw ideas out there and see some stick... awesome man.