The clean channel on the amp works nicely, but on the lead channel, the signal is barely discernible out of the speakers. I see R46 and 47 look burnt on the board, and R67 and 68 look like the wrap on the resistor has cracked due to old age.

On the schematic c38 and 39 are marked to be 10 uf, but I have 100s in there, and c40 and 41 on the schematic are 47 uf, but 68s are installed. I cannot read the resistor values for R44 45 46 47...

I do have a good meter, and scope. Any suggestions would be appreciated.

When checking v+ ground to pin 1 on IC1, the lead channel will kick on as long as I have the positive lead touching the pin from my meter. Next thing to check?Plz keep a bit layman, was years ago that I took digital repair 😂

Also I'm reading 40 volts DC across resistors 46 and 47 which are getting incredibly hot, 6 volts across resistors 44 and 45. The zeners looked to test okay, and I see no problems with the caps there. When I do click on the overdrive channel, the LED on the front comes on very very dimly.

Just got one of these and a 60's 4x12 cabinet for $125, but the lead channel is extremely quiet. I can hear that it has the crunch, so I know that part of the circuit is good.


The amp does not respond to the volume knob on the lead channel, so I'm expecting it's a problem with the pot.

If turns out not to be the volume pot, what other components could cause that pot not to respond on the lead channel?

Also, what would be some good mods that I could add that I can make switchable with installing switches on the front plate?

I have a Frontman 25r amp and the drive select does not work from the switch or the footpedal. The crunch channel is always on. I tested the pedal and the switch for continuity, and both work fine. Any suggestions on troubleshooting this problem?

An added note- The LED indicator DOES respond then to switch is depressed, but the amp still stays on the crunch channel.

Schematic is attached

Thanks!