PS Audio GCPH modification

[Chris74]

Hello All,

I have decided to open up my recently acquired PS Audio GCPH to see what could be in need of upgrading. From what I gather, the primary parts in need of replacement are diodes, signal path resistors and electrolytic caps. Below is an example of what one modification outfit uses in place of the stock parts:

4 x Japanese Riken ½ and 1 watt signal-path carbon resistors (gold-plated leads)
4 x International Rectifier Hexfred ultra-fast soft-recovery rectifying diodes
4 x BlackGate ultra-premium FK-Series electrolytic capacitors

I plan on also replacing the output jacks and experimenting with internal wiring at some point in the future but I think the internal upgrades will be the most logical place to begin with.

My dilemma is locating the right parts and determining their values. I do have a multimeter but need to confirm that I am indeed replacing the correct parts.

Any help provided in regards to location and identification of the parts listed above would be greatly appreciated.

Having some troubles uploading pictures of the internals for illustration but will keep trying.

[Chris74]

Link to pictures of the PS Audio GCPH internals:

ImageShack® - Online Photo and Video Hosting


ImageShack® - Online Photo and Video Hosting

[Chris74]

Update: I contacted PS Audio tech support and requested a GCPH service diagram / schematic. They responded saying they did not have this data to share to end users.

[Chris74]

The (4) diodes which need replacing I believe are the ones located to the lower right on the board (when viewing from above) situated in a row. The (4) electrolytic caps I believe are the small ones located in pairs to the middle left and middle right and just in front of the large caps on the center of the main board. The 1/2 and 1W signal path resistors though I am not sure of and have no idea of how to locate without a schematic or service diagram. The other parts and their locations are just speculation but I think my guesses are logical? Could be mistaken though.....

Any thoughts?

[kevinkr]

Yeah I suspect you are right WRT to the caps and rectifiers, but I suspect that the real action would be inside the gain cells which are probably inaccessible. I'm not sure whether or not any of the suggested changes would result in a significant improvement in performance given all of the complexity. I'd do no more than the caps and rectifiers frankly,

An inveterate tweaker am I, (see old zhaolu thread) but in this case I think you'd be better off enjoying it as is, and then selling it along when you have outgrown it sonically. I've little doubt that there are a plethora of better sounding designs here if you are in the mood for some serious DIY. (Take a look at some of Salas' stuff for ideas)

[Chris74]

kevinkr, Thanks for your input. In addition to the diodes and caps, the generic signal path resistors that currently reside on the board are also something which I believe may be hampering the performance of this piece by quite a bit. Now, if I could only locate them......

Regarding the diodes, does anyone know what setting to use on the multimeter to measure their values?

This is assuming they are not already marked on the parts.

[studeb]

from the pic i would guess they are marked u(f)5404, could be 3A 400V diode

[Chris74]

studem, thanks.

Any idea on how to identify and locate the (4) signal path resistors?

Values should be 1/2W and 1W

[Chris74]

Still having a tough time locating the signal path resistors. Any suggestions?

[studeb]

those are going to be big ones if they are SMD
follow the traces from the input and output jacks
inside the gain cells?