Denon PMA-50 relay to enable amplifier circuit

[mk2]

It might help me to know what the "Feedback processor" CSR6600 does? (see page 43) If you have any ideas from its name or diagram on page 57. Thanks

 

[LTig]

Must be this one:

CSRA6600 | Qualcomm

www.qualcomm.com

Unfortunately no further information available for private people.

 

[RandomEar]

If you want to probe individual chip pins, you'll need sharp probes and maybe some grabbers.

EDIT: These grabbers might be better for the pin spacing you've got there.

 

[mk2]

I think I would find grabbers useful in general, thanks. However for this project they still seem to be large by an order of magnitude? The kind of places the manual seems to expect me to probe are like the "CSR" chip you can see in the last set of photographs, these are surely too small for grabbers and I would need more than a steady hand for sharp probes.

I may have some sharper probes with the little digital oscilloscope I have. I will try and dig that out next time I am able to look at the amp. But these still do not help probe it when the boards are connected together. Early in the manual it suggests using a rig with a ribbon cable which I presume is so the boards remain accessible.

Thanks for these tips

 

[RandomEar]

Yeah, those are probably for bigger chips like DIP packages and jumper connectors, but they can be plugged right into the multimeter. For small SMD stuff, these are the weapons of choice:

• https://aliexpress.com/item/1005005936436715.html
• https://aliexpress.com/item/1005008672054721.html

I haven't seen these exact smaller clips on Amazon, at least not in that quality. They also require some cables with DuPont connectors and something to connect the cables to the multimeter. Maybe you can then disassemble the board as far as necessary, attach the clips and add some tape to keep them in place and re-assemble the board to power up the amp and measure.

 

[mk2]

Wow, those really are incredible (and I don't just mean Walken's dance moves)

 

[mk2]

I ordered some of the clips, they already arrived and look good! They will come in useful for this and future projects.

However I do feel increasingly swimming against the tide here, as it's unclear if I can even obtain replacement MOSFETs, even if I can successfully desolder them and/or diagnose any other faults.

Furthermore, I bought myself a new (old) amp; a NAD 304. I've enjoyed the Denon because it was a fun goal to have a fully digital signal chain right up until the speakers, but such a modern amp comes at the expense of repair-ability and longevity (it broke after only a few years, and I've already sunk a lot of time and want my music back!)

With the NAD I have bounced back to analogue and switches, which gives me a little better usability by having an insert loop that my digital processor is connected to. If I can get the Denon working as a project amp and insert probes into it then perhaps it can be given a second chance with my aspiration to add a digital S/PDIF loopback for the processor.

Thanks for everyone's help here, I will respond in this thread when I have time and any news!