Boss RPS-10 Pitch Shifter / Delay Repair Help?

[outoftune]

Hey everyone, I'm working on a Boss RPS-10, a very cool pitchshifter / delay.

The unit has an extremely low output. I've traced the issue to the first M5218L opamp (IC 13A in the schematic). I think that replacing this should resolve the issue, but I've seen other mention it could be the NE570 compander chip as those often fail and could be shorting something in the circuit. I want to make sure this isn't the problem before replacing the M5218L.

The effects part of the unit does work, I can hear them at a very faint level. Unfortunately I don't have an M5218L (SIP) opamp on hand to just straight up replace it, so I will have to order

Wondering if anyone has advice on how I could verify the NE570 chip is working? If I remove the M5218L, can i inject a signal at the first opamp output to see if the rest of the chain works? Anyone have voltage measurements for a working 570 chip?

Schematic is here: https://www.univertron.com/SAS/manuals/Boss (Roland)/Boss RPS 10/rps10-master-schematic-450dpi.gif

 

[JohnRoberts]

It looks like there are a couple NE570s in there. They are only using 1/2 of the first one. It's labelled compressor and they are generally configured as a 2:1 compressor squashing the dynamic range. The second NE570 labelled expander is stretching the signal back out 1:2.

With a scope or signal sniffer you could try to follow an audio signal from input to output. I see lots of suspects for IC failures.

JR