17PW20 PSU Working but no power lights on LCD

[shepp]

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

-Do not- lower the voltage rating of the caps on the primary.

Although it may not seem like it matters (PFC is 400V), it does because the ringing at the drains puts the voltage across those caps as peak 600V. In fact using 1kV caps would be a good idea. They are cheap from farnell or ebay.

sound advise thank you


still cant find any!

[tom66]

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

-Do not- lower the voltage rating of the caps on the primary.

Although it may not seem like it matters (PFC is 400V), it does because the ringing at the drains puts the voltage across those caps as peak 600V. In fact using 1kV caps would be a good idea. They are cheap from farnell or ebay.

[multimeter]

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

i would stick to the voltage or higher,they are that voltage for a reason.

[shepp]

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

another question will these be ok as replacement caps for the 32"

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MakeTrack=true

cant find them any where else was going to do the 105K ones as well while i was at it but finding it hard to match the voltages up as these are 450v and the others are 630v

cant see why they would be 630v to be fair as the boards only supply max 24vdc and supply is 230vac?

[shepp]

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

arh....makes sense due to the other board having 37" Hitachi wrote on it! lol

[tom66]

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

tested with main board out the 32" Goodmans, the tv comes on but there is no picture, the back light does light up tho and there is sound

is this likely to be the t-con?

if it is this means the 37" needs a new main board, remote, and t-con! jesus!

More likely the 32" board is programmed for a different T-con and so won't display anything on the 37"...

[shepp]

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

tested with main board out the 32" Goodmans, the tv comes on but there is no picture, the back light does light up tho and there is sound

is this likely to be the t-con?

if it is this means the 37" needs a new main board, remote, and t-con! jesus!

[tom66]

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

The main one being that it's a Vestel SCNR..

Yes, Vestel engineers cast a curse on these every time a batch leaves the factory.

[Scenic]

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

[...] there are hundreds of other possible faults that make these things a right nightmare to diagnose.

The main one being that it's a Vestel SCNR..

[shepp]

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

i will swop out the main boards tonight then and see if that sorts the Hitachi out, then order a main board from some where if it powers up, i need to order a remote for it anyway but thought id wait til i get it working first.

will order the 15nf caps tonight then swop all caps anyway on the Goodmans to be on the safe side then retest and fingers crossed that ones sorted

[tom66]

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

17PW20 is cross compatible with 17PW15-8.

If you have too much trouble would just advise buying one on eBay for around 20 quid.

The #1 fault (5 mins off, sometimes 1 second, sometimes 1 hour...) is caused by the two 15n 630V caps near the main switching fets on PSU, but there are hundreds of other possible faults that make these things a right nightmare to diagnose.

[shepp]

hi all, ive recently got 2 lcd's in, 1 being a Goodman 32" with a 17PW20 Psu and a 37" Hitachi with the same board

goodmans turns its self off after about 5 mins - ordered main caps to try changing them 2 x 4700uf 6.3v, 4 x 1000uf 16v, 1 x 2200uf 6.3v and 2 x 1000uf 35v (no bulging caps found but G-Luxon)

the Hitachi how ever does nothing....DEAD, i have swopped PSU's over and tested in the goodman and that turns on and its working fine - any ideas guys? is this a main board issue or inverter?

i could trying swopping the main boards over to eliminate cause i think there the same but before i did that i wanted to see if anyones had this issue before to save myself some time