MXR Micro Amp

Got a MXR micro amp in for service and modification.

MXR-micro amp, repair and mod
MXR micro amp

The fried original TL061 opamp is now replaced with an OPA134 and the old tantalum capacitors was replaced. Rewired the bypass with a new 3PDT switch for true bypass. Mounted a 2,1mm negative center DC jack.

MXR-micro amp, repair and mod
MXR microamp

View of the DC jack.

MXR-micro amp, repair and mod
MXR micro amp

/Krister

Custom Rat pedal

Zeta Sounds take on the proco Rat.

Zeta Sound Rat

Circuit board.

Rat circuit board

Pretty straight forward though. A three way switch for clipping options. No electrolytics in signal path. Now it’s time to tune the circuit.

Gut shot.

Zeta Sound Rat guts

And an another image of the pedal.

Zeta Sound Rat

/Krister

Colorsound Frankenflanger

Customer trying the repaired Colorsound Flanger pedal.

Colorsound Flanger

The circuit went through a massive repair and modification as seen in this image.

Colorsound flanger repair
Colorsound Flanger guts

It’s been modded with a charge pump, lets it run from a standard 9VDC power supply. It also has trimmer that attenuates the output volume. Missing the bottom lid we got a new one manufactured.

/Krister

Colorsound Frankenflanger repair

About the Colorsound Flanger in an earlier post here. Found some schematics that helped rebuild the circuit.

Colorsound Flanger

Gut shot of the pedal in a working state.

Colorsound flanger repair
Colorsound Flanger

So pleased to here it producing flanging sound again. Here’s a short soundclip.

Repaired Colorsound Flanger

/Krister

Boss DD-3 repair.

Here’s another Boss DD-3. The pedal gives signal in bypass, with effect engaged there’s just dry sound.

Boss_DD-3 Repair
Boss DD-3 repair.

Someone has done some repair to the circuitboards power section seen in the upper left on this image.

Boss_DD-3 Repair
Boss DD-3 repair.

The Mode selector rotary switch out of the chassie for replacement.

Boss DD-3 repair
Boss DD-3 repair.

Old vs new rotary switch.

Boss DD-3 repair
Boss DD-3 rotary switch.

So what’s wrong with it. Found that C34 was broken, it did not pass any signal to the expander circuit. Had it replaced and got the delayed signal through the circuit, though at to high level and distorted. C31 was the cause of that problem. With C31 replaced the pedal works as it should. The tantalum capacitors C32 and C33 was also swapped with new ones as they do tend to fail in time. Checked and adjusted the high and low end of the Master clock frequency.

Boss DD-3 repair
Boss DD-3 repair.

Here’s the service notes: Boss DD2-DD3.

/Krister

Variable transformer.

Got hold of a powerstat, an old variable transformer from “The superior electric company Bristol Connecticut, U.S.A”

Variable transformer
Variable transformer.

Also found an old chassie donator. Runs 3A 0 – 230VAC and 0 – 320VDC. Nice for tool for tubeamps. VAC outlet on the right side and VDC on the front panel.

Variable transformer
Variable transformer.
Variable transformer
Variable transformer

/Krister

Nadine’s Distortion

A rare piece of non functional equipment, a Nadine’s Distortion on the workbench.

Nadines Distortion
Nadine’s Distortion

Gut shot, the circuit board in nice condition.

Nadines Distortion
Nadine’s Distortion guts

Component side.

Nadines Distortion
Nadine’s Distortion

The 6552 opamp was burnt, once replaced the pedal’s rocking again. Image of the circuit board with a socketed RC4558 as replacement for the 6552, the old electrolytic capacitors changed and a new battery clip installed.

Nadines Distortion
Nadine’s Distortion

/Krister