Category: WIP

Service on a rare Colorsound pedal

Just love the looks of these old pedals.

The outside consists of three knob, bypass switch for the Fuzz and a treadle for the speed and bypass of the phaser.

Inside the case there’s two separate circuit boards stacked. One for the fuzz and the other for the phaser.

Top circuit holds the phaser, appears to be a four stage phaser.

Bottom side of the phaser cicrcuit board.

The Fuzz circuitboards. A three transistor circuit, a pair of diodes back to back. A Colorsound Jumbo tonebender?

Bottom side.

The issue with the pedal is the phaser, sounds weak in its phasing. The old tantalum capacitors where replaced, the fets bias was recalibrated and the depth was adjusted. Now it sounds as good as new.

Servicing an Ibanez Standard Wau Wau

A vintage Ibanez wah pedal in nice condition, though it sounds a bit off.

The original screw is present along with a battery compartment on the bottom lid.

The guts. Shielded wiring for the signal cables.

Bottom side of the circuit board.

A quick fix for this pedal. The wah potentiometer was loose and just had to be aligned and tightened for the right sweep. The old electrolyte caps were swapped with new ones.

Once again ready to Rock!

Service/mod of a rebranded? Wah Swell pedal.

The pedal on the workbench, branded Förstärkardoktorn.

Förstärkardoktorn(Amplifier doctor) was a Swedish store selling musical instruments back in the days. It even has the original price tag on it.

The wah circuit corresponds a lot with Colorsound Wah Swell circuit, at least for the wah part. As seen in this pic there’s a double gang cermet potentiometer, using the other side as a volume pot.

Solder side of the circuitboard.

Here’s the circuit modified. Removed the passive swell part and wired it for true bypass, added a trimpot for overall output volume and adjusted the tone of the wah.

Service on a defect Soldano SP-77

On the workbench, a Soldano SP-77 in a nice cosmetic condition. It produces a very low, ugly distortion on both channels.

There are no obvious signs of anything wrong on the inside.

However, a voltage control on some critical points spotted the problem. The 100K resistor R24 is no longer conducting.

A photo of the circuit board’s bottom side.

After replacing the defective R24 resistor and the dried-up electrolytic caps, it is now functioning properly.

Retro Sonic Vintage Vibes

The MN3002 BBD in a Retro Sonic Vintage Vibes started making noise. All working conditions are in order so the guess is the BBD chip is not as it should.

The BBD is a MN3002.

Since the MN3002 BBD is hard to find, an extra adjustable low pass filter stage is installed. Allowing the user to set the cutoff frequency. Accessible with the bottom lid of next to the input jack.

A Boss DS-1 in need of service.

It got fed 18V instead of the usual 9V, bypass is working fine but quiet when effect is engaged.

A voltage reading of the op-amp indicated it was fried, +9V on all the pins but the GND connection. Here replaced with a JRC4558, also take a look at the bigger 100uF capacitor to the left.

Here it is desoldered. It did not survive the 18V it was feed. Replaced with a new one and the circuit is working again.

A Supa Tonebender in near mint condition, giving a very weak output signal.

Guts reveals what appears as all original.

Signal generator and a scopemeter isolated the problem to the bypass switch.

Not the typicall bypass switch construction. Note the date stamp 10 MAY 1976.

However a construction that is easy to service.

After a cleanupof the switch and the Radiohm potentiometers, the pedal is back in working condition.

My favorite chorus pedal the Boss CE-2 on the workbench for an ACA to PSA mod and a recap.

Solder side of the circuit board.

Component side.

For the ACA to PSA mod we want to remove D5 and R53 and jumper them.

Component side after the recap and ACA to PSA mod.

Trying a new circuit, a low gain overdrive with an interesting tone control.