Hanns g 32" JT261 back light fault

[shepp]

hi all,

i bought this tv with bad caps replaced them all and the tv worked fine, so i sold it a friend and a few months later it has returned......

now the tv comes on fine but then after say 5 mins sometimes the back light goes out.....the sound remains.....and the picture is there...but no back light

so i order a 2nd hand invertor....it comes i fitted it....tv works a treat

few days later i ring my mate and tell him im just gonna test it again before i drop it round, put it on and low and behold same fault! now im guessing its the power supply but now when i test it.... it wont fault on me!

has anyone got any ideas or if anyones had similar issues i could really do with the input

check out the pictures the diode near the transistor looks a bit suspect but i checked it with diode test and it tests at 880 1 way, so think this is roughly ok?

[tom66]

Re: Hanns g 32" JT261 back light fault

Check the 24V on the PSU. If it's unstable, that could be the problem. Also, it looks like you used inferior capacitors which may be causing your issue.

[anotherdude]

Re: Hanns g 32" JT261 back light fault

Check the 24V on the PSU. If it's unstable, that could be the problem. Also, it looks like you used inferior capacitors which may be causing your issue.

tom, if you don't mind me asking are you refferring to the SD caps?

if so again if you don't mind could you explain why they are inferior?

[tom66]

Re: Hanns g 32" JT261 back light fault

They aren't made for use in switching power supplies like that due to their high esr, low ripple current, and short lifespan.

[shepp]

Re: Hanns g 32" JT261 back light fault

Check the 24V on the PSU. If it's unstable, that could be the problem. Also, it looks like you used inferior capacitors which may be causing your issue.

i will check all voltages and post results tomoz, as for caps, thats all i had at the time, i dont mind ordering some more though if it will fix the issue, i might even have some better ones some where that i can use fingers crossed

[shepp]

Re: Hanns g 32" JT261 back light fault

[QUOTE=anotherdude;321752]tom, if you don't mind me asking are you refferring to the SD caps?

if so again if you don't mind could you explain why they are inferior?[/QUOTE

there is 2 SD ones and a couple of Nichicon im guessing there the ones you mean..as they are the cheap ones


SORRY TRIED TO DELETE THIS POST BUT CANT SEEM TO DO IT

[tom66]

Re: Hanns g 32" JT261 back light fault

Chang, SD, Lelon, Ltec, etc.
All the same rubbish.

[shepp]

Re: Hanns g 32" JT261 back light fault

Sorry for delay, not really had much time to test

right then voltages are as follows:

in standby for invertor all 0v

when switched on invertor from right to left see pic

when on: when fault:
1 = 4.8v = 0v
2 = 0v = 0v
3 = 24v = 22v
4 = 24v = 22v
5 = 24v = 22v
6= 24v = 22v
7 = 0v
8 = 0v
9 = 0v
10 = 0v

from top to bottom connector on main board see pic
mainboard voltages: standby: / couldn't get it to fault again to post these readings
1 = 0v 0v
2 = 0v 0v
3 = 0v 0v
4 = 0v 0v
5 = 12v 0v
6 = 12v 0v
7 = 5.1v 5.1v
8 = 5.1v 5.1v
9 = 5.1v 5.1v
10 = 3.7v 0v
11 = 0v 0v
12 = 4.8v 0v

[tom66]

Re: Hanns g 32" JT261 back light fault

Yeah, so your 24V measures 22V, this is your problem.

[shepp]

Re: Hanns g 32" JT261 back light fault

Yeah, so your 24V measures 22V, this is your problem.

round here somewhere? see pic

would you say its worth just replacing the caps for the 24v section in the pic, or does it sound like it could be something else causing this problem?

[tom66]

Re: Hanns g 32" JT261 back light fault

First replace the crap caps -- this gives us a base line to work from.

[shepp]

Re: Hanns g 32" JT261 back light fault

First replace the crap caps -- this gives us a base line to work from.

ok, will do that then post when ive retested, might be some time next week depends if i have to order any or not

[shepp]

Re: Hanns g 32" JT261 back light fault

just ordered all Panasonic ones so they should be here probably tuesday at latest

cheers tom

[tom66]

Re: Hanns g 32" JT261 back light fault

The one Nichicon can probably be kept though.

[shepp]

Re: Hanns g 32" JT261 back light fault

quick update = day 1 of testing...so far so good

will test again tomoz

[shepp]

Re: Hanns g 32" JT261 back light fault

Day 2 of testing = FAILED

SAME FAULT came on for a bit then back light went off.....22 V again

[martyparish]

Re: Hanns g 32" JT261 back light fault

It could be possibly that the inverter is pulling the voltage down. Can you disconnect the inverter from the PSU and then power it up and test the 24v rail?

[shepp]

Re: Hanns g 32" JT261 back light fault

Quote from first post - "so i order a 2nd hand invertor....it comes i fitted it....tv works a treat" but then same problem...

so it is unlikely that the 2 invertors have the same fault

[tom66]

Re: Hanns g 32" JT261 back light fault

Consider C16 capacitor.

[shepp]

Re: Hanns g 32" JT261 back light fault

Consider C16 capacitor.

where abouts mate, i can see C15 but no 16