Author Topic: 17pw20 psu problem ? no picture (Read 9861 times)

mali67 · « **on:** August 04, 2012,11:33:47 »

I have an ONN 42" unsure of the model but has the vestel 17pw20 psu.
all voltages seem correct,
problem is when first turned on picture with stay on for upto 5 seconds then go off i still have sound
there are 2 15bf 630v caps that look ok but suspect they could be part of the problem, i dont have any of these to try is thee an equivelent i could try ? could it be something else ?
cheers

Mulja tv repair portal · « **on:** August 04, 2012,11:33:47 »

sparky · « **Reply #1 on:** August 04, 2012,12:26:39 »

hi
do the backlites stay on?
dave

mali67 · « **Reply #2 on:** August 04, 2012,12:28:13 »

no the backlights go off
ive tried another inverter

Mulja tv repair portal · « **Reply #2 on:** August 04, 2012,12:28:13 »

Turnip · « **Reply #3 on:** August 04, 2012,12:45:38 »

Hi Mali67,

Would always change those 15nf/630v caps supplying the 24v line feeding inverter - heaps on Ebay. They don't always bulge but are the first things to check - replace anyway, they're cheap - Chris.

mali67 · « **Reply #4 on:** August 04, 2012,13:00:12 »

cheers chris i looked on the bay but couldnt find any 630v ones, cheers robbie

Turnip · « **Reply #5 on:** August 04, 2012,13:17:12 »

Hi Robbie,

I didn't either, but got some 1 kv ones from China, bought quite a few so if you want a couple cheap, send an Email - Chris

Mulja tv repair portal · « **Reply #5 on:** August 04, 2012,13:17:12 »

bobi.bt · « **Reply #6 on:** August 04, 2012,13:18:49 »

hi mali67
i haved the same problem with with the same vestel supply,and i have changed the 2 caps 15nf with 20nf or 22nf 800v (the voltage could be bigger to,just must to be more than 600v).and the tv work great.
(one of the 2 caps was showing 2 nf measured with instrument.

mali67 · « **Reply #7 on:** August 04, 2012,13:23:06 »

cheers bob , ill replace them and find out :P
and chris ive mailed you cheers

Turnip · « **Reply #8 on:** August 06, 2012,10:13:41 »

Hi Robbie,
In the post - honest - Chris

mali67 · « **Reply #9 on:** August 06, 2012,17:21:44 »

cheers chris , will post a book of stamps off tomorow, will post back with results

chrissie jones · « **Reply #10 on:** August 07, 2012,03:31:02 »

ive got 18nf in mine.can i replace em with 15nf..

Turnip · « **Reply #11 on:** August 07, 2012,13:35:21 »

Hi Chrissy,
Folks say 20 / 22nf does the job, never tried but - wouldn't worry too much - Chris

chrissie jones · « **Reply #12 on:** August 08, 2012,03:06:26 »

thanx turnip...but i used 15nf instead of 18nf and all works fine.

mali67 · « **Reply #13 on:** August 08, 2012,07:42:31 »

caps arrived (cheers chris) but still same problem , screen flashes on then goes off

watteau · « **Reply #14 on:** August 08, 2012,11:44:21 »

Hi,
If you've still got the 24v inverter supply when backlights go off, you
could try Q841,D861, or C904, off pin 12, PL802 (the backlight on/off).
Does this voltage change when the backlights go on/off?, possible main pcb
switching inverter off.
Regards,
John

Mulja tv repair portal · « **Reply #14 on:** August 08, 2012,11:44:21 »

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Author Topic: 17pw20 psu problem ? no picture (Read 9861 times)

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