vestel 17pw26-4 weired fault,help

[promo7uk]

im a tv engineer and i cannot for the life of me find this sodding fault.

i have a vestel 17pw26-4 from a jvc 32" tv,

i have replaced q813 , q814 + fan 7711 chips. now psu works but,, drop a load onto it voltages drop.. all of them 3.3v 12v 24v , every single voltage slowley drops.. anyone had same problem and manage to fix please let me know for furture ref as its piddling me off, cheers

[senndogg]

Re: vestel 17pw26-4 weired fault,help

does the standby voltage drop too? can you check the voltage in the 22/33uf 35/50V small cap in the primary side?

[ReeceyBurger123]

Re: vestel 17pw26-4 weired fault,help

I hate vestel boards especially the 17pw20-26 models when ever you fix one problem another occurs, its probably cheaper to replace the board (parts and time wise). I have seen the output voltage drop due to bad pfc try checking the voltage on the main filter capacitor should be around 385v while on if its lower than that check the pfc. I had a 17pw26-4 that had voltage dropping issues on the output and it turned out to be the pfc the main cap was only getting 330v dc it turned out to be the pfc, I ordered parts from http://sparedparts.com/parts/manufac...ory/vestel/P29