Ok I will check the transformer in the back. There are 3 wires on the low voltage. One is the center tap. Voltages according to schematic are 40v and 16v. I hope this is what you are talking about. I know you said 15v but I don't see that on the print.

I have my original M80 combo amp with the speaker. I haven't used it for some time and was fully operational when I stored it. I just got it out and hooked it up and found that the 2 inputs don't work. Also there is no light on the overdrive and when I plug in the pedal no light on that. The power light goes on and if I plug into the power amp in with my guitar, I hear my guitar. Looks like I'm not getting power to the inputs or something. Anybody out with some ideas? Would really appreciate it