Malfunctioning Peavey Classic 30 - a summary report

[slidincharlie (Carlo P)]

I have started here below three threads on a fu**ing Classic 30 that gave me a few headaches. This is a report of the repair jobs done.

1) smoke from the power tubes area: the CR6 diode on the plates of two power tubes got burned. I replaced it with two 1N4007 in series.

2) smoke from the preamp tubes area: R67 (180 ohm resistor feeding the reverb IC) got burned, due to a bad reverb IC. I replaced the resistor and trashed the IC (don't have a replacement at hand now).

3) loud crackles, pops and squeals, with blue light flashing inside the power tubes: I tossed the four EL84 and put a fresh quartet (JJ) in.

4) cold (dead) heaters in the preamp tubes: this was an error of mine - my bad! The filaments were on, but they have so faint a light that they really looked off! The tubes are three EH 12AX7. I thought that only Sovtek 12AX7LPS had apparently cold filaments. Actually these filaments here were alright.

Thanks to all the guys that helped me in troubleshooting! I have learned a lot along the way.

[Enzo]

Glad it worked out.

The heaters are not really colder. The cathodes have to be a certain temperature to work right. But the heater filament may extend farther out from the ends of the cathode in some tubes, making it more visible. The part of the heater that matters is not out where you can see it, it is in side the cathode.

[slidincharlie (Carlo P)]

Thanks Enzo.
You're right about the heater temperature of course.
By "cold" I meant "not bright" or apparently lifeless... sorry for my English