I have a recently-acquired Pioneer SX-850 with a known protection relay issue. I purchased the receiver with the protection issue as a known problem. I removed the bonnet and base plate and checked power supply board voltages - all within 0.5v - 1v of spec. O-scope probing of all supplies gave me a nice, clean line. I started the power amp calibration per the service manual, but am having issues with the DC offset. My meter reading fluctuated all over the place - especially on pin 25 of the power amp board. The scope showed the same thing, with the average voltage reading being around -6v with VR1 fully counter-clockwise: Pin 10 is a little better, but I can't get close to 0v - about 30mV is as close as I can get: Output transistors checked good, as well as the 8 transistors on the power amp board (all were checked while soldered in place). With the power off, I ran VR1 - VR4 back and forth several times, then set them back to calibration position before powering back up. I'm guessing a power amp capacitor replacement is in my future - what do you think?