Akai LCT3201AD black screen in 2-3 sec

[mcross]

Ok i know its junk but trying to help out a buddy, its a Akai LCT3201AD ,
Power supply is putting out correct volts on all pins, recaped alot of bad 220uf on the main and tuner board, get geen light and screen for a few sec, power light stays green and volts remain good to inverter. inverter bad? have done the 1 back light at a time thing , no good. ? any ideas?
can post pic's but no sure theres a need with the info i have.
Thanks
Mike

[tibimakai]

Re: Akai LCT3201AD black screen in 2-3 sec

http://blog.coppelltvrepair.com/2011...not-power.html

[mcross]

Re: Akai LCT3201AD black screen in 2-3 sec

http://blog.coppelltvrepair.com/2011...not-power.html

Thanks for the link , but been there done that on power supplys. Mine is getting and maintaning correct voltage, but black screen in 2-3 sec after start up. Do you think i missed something?
mike

[retiredcaps]

Re: Akai LCT3201AD black screen in 2-3 sec

2 seconds to black can be

a) bad ccfls
b) bad ccfl wiring
c) bad inverter transformer (secondary windings)
d) bad caps

All explained with posts #19 and #20 at

https://www.badcaps.net/forum/showthread.php?t=10419

[Jasgriff]

Re: Akai LCT3201AD black screen in 2-3 sec

Try what retired caps suggests in his post and let us know you findings. If it was me I would make sure that u can see your desktop with a flashlight. This means you can focus on why the CCFL's aren't working.

[mcross]

Re: Akai LCT3201AD black screen in 2-3 sec

will do and let you know
Mike

[mcross]

Re: Akai LCT3201AD black screen in 2-3 sec

Ok did some checking, have sound and fant video, just no back light , have replaced around 20 220uf caps all bad (tested with my blue ESR meter) a few 470uf and a few 22 uf, . all caps on ps, most 220uf where on the main board and tuner, inverter is getting 24 v , all transformers test same. I am stumped.
Mike

[retiredcaps]

Re: Akai LCT3201AD black screen in 2-3 sec

If you have no backlight versus 2 seconds to black, that is totally different.

Absolutely no backlight (i.e. no 2 seconds to black) can be

a) open fuse or fuses
b) shorted mosfet or transistor on the inverter board
c) bad inverter pwm chip

[selldoor]

Re: Akai LCT3201AD black screen in 2-3 sec

I dont think he means NO back light as in post3 he says it is on for 2 to 3 secs.

[retiredcaps]

Re: Akai LCT3201AD black screen in 2-3 sec

I dont think he means NO back light as in post3 he says it is on for 2 to 3 secs.

But now in post #7, he says no backlight so something might have changed?

[budm]

Re: Akai LCT3201AD black screen in 2-3 sec

No pictures of any boards either.

[mcross]

Re: Akai LCT3201AD black screen in 2-3 sec

Ok guys to clear this up abit, had 2 sec to black, replaced what ended up to be close to 30 caps, then got no back light, and then found a bad transitor on the inverter, now all is good, works like new, by the way most ever cap replaced was 220uf, and few others
Thanks all
Mike

[mrwebo]

Re: Akai LCT3201AD black screen in 2-3 sec

which was the transistor you replaced I have the same problem and Replace the capacitors that were bad the volatages correct font need your help please I would greatly appreciate it from ... thanks

[mrwebo]

Re: Akai LCT3201AD black screen in 2-3 sec

hello sorry the supply voltages are correct Replace capacitors 470uf and 220uf but still turns on and shows the logo of akai and off and the LED remains lit in green I think is the problem of inverter.
What is the transistor that was damaged in your case please driving me crazy this tv. sorry for the English but I use google translator ...... thank you very much

[mrwebo]

Re: Akai LCT3201AD black screen in 2-3 sec

I think it is an inverter transformer and measured with the multimeter the tips of this and gives me strength 180khoms and others give me a measure of 1.5 khoms think that's it.
how I can do to turn the trick to remove the transformer protection system or something please help