Replacing caps of deflection circuit on a Sony PVM-2950QM

[xga]

Hi Guys,

I'm interested in replacing the capacitors of the deflection circuit in my Sony PVM-2950QM to fix some geometry issues. Has anyone here replaced the deflection caps in one of these PVM's before? Skips?

I haven't opened mine up yet, but I've had a look at the service manual http://neohyphengeo.com/Sony%20PVM-2950 ... Manual.pdf and I'm trying to determine which board is responsible for the deflection circuit. I could be wrong, but I think it might be the "DX" (Geometric Distortion Correction) board, which I believe plugs into an extension board connected to the main "A" board.

According to the electrical parts list in the service manual, I count 33 ceramic chip caps, 4 film caps and 4 electrolytic caps (a total of 41 caps) on the "DX" board. If this "DX" board is in fact the deflection circuit, should I be replacing all 41 caps?

Thanks in advance for any information you can offer.

Cheers!

[donluca]

Not sure if that's the deflection board.

Anyway, you want to replace just the electrolytic capacitors and the high voltage ones.

Generally film and (especially) ceramic capacitors don't go bad but those which have very high voltages (>200V) through them might start having issues after a bit so it's worth changing them.

[Skips]

Deflection circuits are typically around or by the flyback transformer (typically but not all the time). The type of capacitors that need to be replaced are the electrolytic capacitors. Whenever I do not exactly know I look for markings on the PCB's that point to anything that sounds like geometry or simply start re-capping the side of the board where the flyback is.

[MKL]

The deflection circuits are in the area where you have the following components:

Horizontal drive transformer (T501)
Horizontal output transistor (Q505)
Vertical IC (IC1601)
Flyback transformer (T504)

So it's in the right part of the A board. Of course there are also many other things on the A board (audio etc.).

HV polyester caps also fail a lot.

[xga]

Thanks for the replies guys.

MKL, I've located all four of those components on the right hand side of the A board. According to the parts list, on the A board I count 178 caps (ceramic, mylar, film and electrolytic), with 75 being electrolytic. So should I just be replacing all of the electrolytic and mylar / polyester caps right of the Vertical IC (IC1601) or is there a better way to determine which caps needs to be replaced?

Apologies for the noob questions.

[donluca]

Definitely all the electrolytic caps and the high voltage polyester ones. Look at their rating on the service manual and change all those with 200V rating or more.