Oops, my error. It has been some time since I worked with a PGP 8.1. The "1" terminals are the high voltage secondary, aren't they. I think it's 2S and 2F that are the primary, and that's what I should have said to measure, VAC. Measuring across the open power switch should give you the proper 120 ish reading too, but over the years we have seen quite a few instances where folks get screwy numbers when trying to measure AC with various meters. At any rate, measuring right at the power transformer primary with the power switch on should give you a good reading if the meter is cooperating.
When I said the board is blown, I did mean that some components on the board are blown, not necessarily a failure of the board itself. One can rework a PC board with replacement components, but sometimes it's pretty dicey to do without damaging it by lifting copper pads or traces. You would probably want to replace all of the semiconductors since it may have been running quite hot for 7 years. I would also measure the resistors to make sure they have maintained their value. IIRC John had a trimmer resistor on that board. If you replace that trimpot, be sure to set it to the middle of its range before you turn the amp on. If it is all the way to the 0 ohms end you can end up blowing transistors.
