mtjames2010
New member
- Joined
- Aug 26, 2015
- Messages
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Amp: Mark IIb
Year: 1982
Style: Blonde
EQ: None
Reverb: Not Working
Schematic: http://issuu.com/mtjames2010/docs/mkiib_schemo
Under Chassis Layout: http://issuu.com/mtjames2010/docs/mark_iib_tube_chart
Problem 1: Under Chassis Footswitch Jack seems to control a slight gain boost on both rhythm and lead channels when engaged but cannot get reverb response. I spoke with customer service who said that the jack should only control reverb and EQ, if applicable. I don't have EQ so they said it should only be a reverb control that auto engages the reverb circuit when cable is unplugged. To make things more confusing, the schematic I received from customer services shows a gain boost ft. switch, a channel ft. switch jack, and an EQ ft. switch jack but no reverb footswitch jack.
1 - Can anyone clear up this confusion an explain what controls what?
2 - Does anyone have the schematics for the Mesa Mark IIb switching pedals for me to build the switching capabilities into a custom pedal board? I know the resistances have to be correct but I'm not sure what they are.
Problem 2: Reverb not working. I did the following:
- Checked and confirmed continuity at transducers on both sides of reverb tank.
- Changed preamp tubes
- Checked and changed input/output wires and cleaned terminals and jacks at both tank and amp
- Checked for reverb with switched engaged, disengaged, and unplugged
- Tried a reverb tank from another amp
1 - Is it possible to have a reverb tank offer full continuity and not work?
2 - Any ideas on troubleshooting?
Year: 1982
Style: Blonde
EQ: None
Reverb: Not Working
Schematic: http://issuu.com/mtjames2010/docs/mkiib_schemo
Under Chassis Layout: http://issuu.com/mtjames2010/docs/mark_iib_tube_chart
Problem 1: Under Chassis Footswitch Jack seems to control a slight gain boost on both rhythm and lead channels when engaged but cannot get reverb response. I spoke with customer service who said that the jack should only control reverb and EQ, if applicable. I don't have EQ so they said it should only be a reverb control that auto engages the reverb circuit when cable is unplugged. To make things more confusing, the schematic I received from customer services shows a gain boost ft. switch, a channel ft. switch jack, and an EQ ft. switch jack but no reverb footswitch jack.
1 - Can anyone clear up this confusion an explain what controls what?
2 - Does anyone have the schematics for the Mesa Mark IIb switching pedals for me to build the switching capabilities into a custom pedal board? I know the resistances have to be correct but I'm not sure what they are.
Problem 2: Reverb not working. I did the following:
- Checked and confirmed continuity at transducers on both sides of reverb tank.
- Changed preamp tubes
- Checked and changed input/output wires and cleaned terminals and jacks at both tank and amp
- Checked for reverb with switched engaged, disengaged, and unplugged
- Tried a reverb tank from another amp
1 - Is it possible to have a reverb tank offer full continuity and not work?
2 - Any ideas on troubleshooting?
