Mark IIB New Owner Couple Questions

[davec69]

I recently ran across a great deal on a MKIIB with 100/60, EQ and Reverb which has been converted to a rack setup, and I'm loving it. Much simpler setup than my previous MKIV.

My first question has to do with the reverb. Since it's in a rack configuration, the reverb is not connected. I notice that when the reverb knob on the rear is at zero, I get no output from the amp regardless of the front panel settings. The reverb seem to work like a overall master volume. Is this normal, or does it sound like some mods have been done?

Also, I know this is common on older amps, but I'm missing one of the EQ slider knobs. It broke off right where the slider enters the amp, so I can still adjust it with my finger. I'd like to replace the slider just for looks. Are they still available?

Finally, is there a schematic somewhere for building the channel switching footswitch with LED, I'd like to build one up. I don't need the EQ/Reverb footswitch, but the channel switching would come in handy.

 

[JOEY B.]

My first question has to do with the reverb. Since it's in a rack configuration, the reverb is not connected. I notice that when the reverb knob on the rear is at zero, I get no output from the amp regardless of the front panel settings. The reverb seem to work like a overall master volume. Is this normal, or does it sound like some mods have been done?

It sounds like your amp may have the Post FX Volume modification. It is a common mod for the IIB amps.

 

[davec69]

Thanks for your response. Can you tell from these pics, if that's the case?

My first question has to do with the reverb. Since it's in a rack configuration, the reverb is not connected. I notice that when the reverb knob on the rear is at zero, I get no output from the amp regardless of the front panel settings. The reverb seem to work like a overall master volume. Is this normal, or does it sound like some mods have been done?

It sounds like your amp may have the Post FX Volume modification. It is a common mod for the IIB amps.

 

[>Photi G<]

I don't see a socket for V4, so it looks like your amp never had reverb. The pot in the back of the amp was likely added as the "Post FX Volume" as Joey said.

As far as the EQ slider, any 50K? linear potentiometer should work.

The footswitch is really simple. Here's a schematic:

 

[davec69]

Thanks for the info on the reverb.

Regarding the EQ, it works fine. I can adjust by moving the remaining bit sticking out the panel. I'm just looking to replace the slider for the appearances.

Not sure why, but I can't see the Schematic image

I don't see a socket for V4, so it looks like your amp never had reverb. The pot in the back of the amp was likely added as the "Post FX Volume" as Joey said.

As far as the EQ slider, any 50K? linear potentiometer should work.

The footswitch is really simple. Here's a schematic:
http://www.mylespaul.com/forums/members/-photi-g--albums-temporary-picture34111-rhythm-lead.jpg