17PW20 PSU Working but no power lights on LCD

[shepp]

Re: 17PW20 PSU Working but no power lights on LCD

I need an esr meter really, I'm thinking about making one tho

[vinceroger69]

Re: 17PW20 PSU Working but no power lights on LCD

same as but saving up for one of rusmikes ones he does a very good price shipped to the uk.

[shepp]

Re: 17PW20 PSU Working but no power lights on LCD

same as but saving up for one of rusmikes ones he does a very good price shipped to the uk.

you got a link for it....so i can have a look

[shepp]

Re: 17PW20 PSU Working but no power lights on LCD

37" up and running Saturday, just swopped main board and its working a treat

thanks guys for the input

gods knows how meny ive fixed now...thanks to this forum

[shepp]

Re: 17PW20 PSU Working but no power lights on LCD

BAD NEWS the goodmans has returned with similar fault, although ive found that its something to do with the 3v yellow cable that goes to the back light, any ideas what to check or replace on this circuit? ive noticed that when the tv is brought out of standby there is no 3v to the back light all other voltages are stable, but when there is the 3v's the tv works ok but then switches off after about half an hour, it sounds like a bad cap but ive replaced all the main caps

[tom66]

Re: 17PW20 PSU Working but no power lights on LCD

The Vestel main board will do a self-test when first plugged in, if this fails it will go into "lock out" mode where it won't do anything. So, check the 24V peaks to 24V briefly. Honestly, these power supplies are so much trouble. I just replace them with a refurb 17PW15-8 or similar, those seem to last.

[shepp]

Re: 17PW20 PSU Working but no power lights on LCD

i have noticed on some repair kits there is a voltage reg 5v, and C901 cap i havent replaced them, so for the sake of a couple of quid im gonna get the C901 cap first which is 4.7uf @ 50v then see if that does it, cant see voltage reg being faulty if im getting 5v stable,

24v comes on, then when the set powers back to standby when the 3v isnt present it shuts down the voltages so all the other voltages are fine.

only caps that will be left to replace will be the little ones, 100uf 16v etc, im determined to try and fix this one because ive replaced so many parts im sure it will last a long time, but saying that theres only so much on one tv you can take.....lol

[tom66]

Re: 17PW20 PSU Working but no power lights on LCD

See the tiny red caps near the big transformer. These tend to fail o/c.

[shepp]

Re: 17PW20 PSU Working but no power lights on LCD

ive changed them already, so they should be ok

[tom66]

Re: 17PW20 PSU Working but no power lights on LCD

Yeah, they could have failed again. Just check them on a cap meter.

[shepp]

Re: 17PW20 PSU Working but no power lights on LCD

Yeah, they could have failed again. Just check them on a cap meter.

there reading 34nf in circiut, both are, so gonna take them out tomorrow and retest because they should only be 15nf

[tom66]

Re: 17PW20 PSU Working but no power lights on LCD

If they are reading a higher capacitance they could be leaky and this could be a sign of failure.

I'd estimate ~85-90% of these Vestel PSU failures are due to them.