Sharp LC-37SB24U two seconds to black

[tsm174]

I'm working on this tv which will turn on briefly, then go black. Symptoms are almost identical to what someone else posted about a few years ago here: (https://www.badcaps.net/forum/showthread.php?t=17101).

When I turn the tv on the picture comes up with audio for about 2 seconds the picture then goes out. I can still see the picture with a flashlight and hear the audio.

From some other reading I suspect either the inverter board or maybe the a bad lamp but I'm unsure how to proceed.

(I do have another picture of the board with all the video/audio inputs on it but it's on my phone which is dead at the moment)

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

Anyone know how I can determine if the inverter is bad or if it's a bad lamp?

[hazi12]

Re: Sharp LC-37SB24U two seconds to black

Measure the resistance to the inverter transformers, it must all be the same.

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

The inverter transformer is the one with two wire windings, right? (6 of them on my board). Where do I measure across - where do I start? And as far as measuring to the transformer, which pin? There 10 pins on each.

[ammarben]

Re: Sharp LC-37SB24U two seconds to black

The inverter transformer T7501;T7502...mesure the secondary winding
they must all be the same

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

Thanks. Is the secondary winding the one with 8 fins, not four? There are four pins on that half of the transformer. I tried to measure resistance across all combinations of the pins on a couple of them and get an open circuit so I guess I'm not measuring the right things. I'll see if I can find a pin diagram for the transformer.

[ammarben]

Re: Sharp LC-37SB24U two seconds to black

are you using the ohmetre to test the transformer?

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

yes. I can measure some resistance across the primary windings, but I don't get any resistance on the secondary windings (or what I think are the secondary windings).

[ammarben]

Re: Sharp LC-37SB24U two seconds to black

https://www.youtube.com/watch?v=b36w2GNrH6Y

http://preher-tech.com/documents/tes...ormersinlcdtvs

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

Thanks, I'll check those out a little later on.

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

Ok, finally got around to checking these. Secondary windings (two per transformer) all measure around 550 ohms. Didn't find any blown resistors on the inverter board either.

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

After re-installing the inverter board and doing one final reset (plugging in TV with vol + chan - pressed), it seems to be working all well again!

It's nice to have it working again, but a little frustrating to not really know what the problem was to begin with.

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

resurrecting my old thread - the tv went back to it's old behavior again. 2 seconds to black.

Based on other posts I was able to jump C7558 to fire up the tv, reset the lamp error and monitor errors, and the TV looks good.

I was able to verify with the test patterns in the service menu that all the bulbs are firing (as far as I can tell - the whole screen looked bright white.)

BUT, I read that leaving c7558 jumped is a fire hazard, which I don't want to leave. Is there a way to further diagnose what the issue might be?

[tsm174]

Re: Sharp LC-37SB24U two seconds to black

At this point I'm more or less ready to throw in the towel, so I opened up the panel to inspect for bad bulbs. Again, while I think they are all lighting, I did find one that has some black at the end of the tube. Maybe this one is failing?

[budwich]

Re: Sharp LC-37SB24U two seconds to black

I would say that bulb is your likely issue. Its probably failing to start some times, increment a counter which eventually causes your set to turn down and not run any more.

[Nick's Tvs]

Re: Sharp LC-37SB24U two seconds to black

My set has its top CCFL that won't light up. I swapped it with the one right below it and tried again to make sure the issue was with the specific light, and it is.
I have another 37" Sharp in the shop but it uses different ccfls that are ever so slightly longer and won't fit properly. Where can I buy a replacement light for it?
I also have a samsung LCD 40" that was dropped and somehow everything remained intact except one of the ccfls broke and I need one for that model as well. Where can I buy these?? Also how do I figure out the specs on these? Never had to replace a CCFL before.

http://www.ccflwarehouse.com/30x83fuspcc.html

Would this work for this set??

[Rider]

Re: Sharp LC-37SB24U two seconds to black

ccflwarehouse biggest rip-off U'll ever see!
I just repaired a 19" Samsung TV/Monitor that needed 1 ccfl
The set uses 2 of them so decide while I was in there would change both
ccfl warehouse wanted $9.95 US a piece + $17.95 shipping and a 2 week wait!
they were 481mmX2.4mm your standard 19 inch monitor size
So here's what I did go to Aliexpress (China's Amazon)
Type in the size I was looking for...
And sure enough found a lot of 10 for $10 US and FREE shipping
toke 3 weeks but was not in a rush!
TV works again total cost of repair $2 bucks!

[michael dranfield]

Re: Sharp LC-37SB24U two seconds to black

At this point I'm more or less ready to throw in the towel, so I opened up the panel to inspect for bad bulbs. Again, while I think they are all lighting, I did find one that has some black at the end of the tube. Maybe this one is failing?

Its a common problem with sharp sets and is usually caused by the white plastic holder the lamp is clipped into making a bad connection to the CCFL.

[michael dranfield]

Re: Sharp LC-37SB24U two seconds to black

Have a look at this guys.