EAY39333001 PSPU-J704A no VS/VA

[paulstef]

Hello,

does anybody have useful information to troubleshoot this power supply. It boosts the input voltage to 383V and logic voltages are there also, no VS nor VA though. What I have done/measured so far:

Disconnected the board from logic board and YSUS. Should come on automatically.

- checked all electrolytics, checked resonant PSU caps, checked all bigger semiconductors (no shorts), white ceramic and other power resistors, all smaller diodes, replaced L6599.

- L6599 doesn't seem to get a voltage higher than its reference voltage of 1.25V at pin 5 STBY, so it probably stays in a so-called idle state.

There is one schematic of this PSU on the internet which has nothing to do with this board, looks like it's from a LCD TV...

[cliff_hootarski]

Re: EAY39333001 PSPU-J704A no VS/VA

http://elektrotanya.com/?q=showresult

Did you get the schematic from here?

If not type EAY39333001 in the search field.

[paulstef]

Re: EAY39333001 PSPU-J704A no VS/VA

http://elektrotanya.com/?q=showresult

Did you get the schematic from here?

If not type EAY39333001 in the search field.

Yes, for some reason this schematic is all over the place. It has a big 24V output and no VS/VA whatsoever, parts do not correspond at all. Definitely an error.

The TV I have is a plasma TV.

[paulstef]

Re: EAY39333001 PSPU-J704A no VS/VA



This training manual shows a power supply very similar to the one I have. Maybe I can go from here.

[paulstef]

Re: EAY39333001 PSPU-J704A no VS/VA

After finally measuring the L6599 circuit with an oscilloscope it turns out that the switched bus voltage could be measured unchanged over C801 , the resonant 33n/1600V capacitor.

Replaced it and circuit works. So even though it showed correctly 33n with my multimeter it had still some kind of high impedance in series.

:-)