Yamaha CH-01 Chorus repair

A chorus from the -80:s, the Yamaha CH-01. Based on the MN3009 256 stage BBD chip and the MN3101 clock generator.

Yamaha CH-01 repair
Yamaha CH-01 Chorus

Had the circuit recaped and trimmers adjusted for bias, clock speed and depth.

Yamaha CH-01 repair
Yamaha CH-01 Chorus circuit board

And here we have a chorus once again delivering.

Yamaha CH-01 repair
Yamaha CH-01 Chorus

/Krister

Spare parts

Received a shipment with parts for a Marshall 2205. Thumbs up for Tube-Town, they sent chocalate with the package!

Parts Marshall 2205
Marshall 2205 parts with chocolate

/Krister

Malfunctional Zachry D250 mono block

Here’s a Zachry D250 solid state amplifier. It stopped working producing only a 100Hz noise. Look at them blue filter caps, seems a bit swollen.

Zachry D250 repair
Zachry D250

Here’s a picture from the bottom of the caps.

Zachry D250 repair
Zachry D250

Those caps are out of date. Had a hard time finding 15000uF 63V caps with a diameter of 35mm. Finaly found and ordered F&T :s with the right values but a diameter of 40mm. I should be able to fit hem.

/Krister

Laney Klipp 100

An old Laney amp that needs som tendering.

Laney Klipp100

Blows the main fuse. Tinkered with as it has a master volume pot installed and traces of other activites.

Laney Klipp100
Laney Klipp100

Components close up.

Laney Klipp100
Laney Klipp100
Laney Klipp100
Laney Klipp100

Checked the power transformer and it seems to be functional. I’ll start with recapping them old electrolytes.

/Krister

Boss DD-3 repaired

Checked the switch for D.TIME due to the problem of changing from 200mS to 800mS of delay. Found it’s not the cause. Had the wiring from the switch resoldered and it’s hey, it’s back in normal operation! Also fixed the knob for E.LEVEL wich was glued in place.

Boss DD-3 repair
A Boss DD-3 repaired

/Krister

Boss DD-3 repair

Got a Boss DD-3 on the workbench.

Boss DD-3 repair
The Boss DD-3 pedal

Got some problem with the pots I was told. Nice and clean on the solder side of the circuit board.

Boss DD-3 repair
Solder side of the circuit board

Here’s a picture of the component side.

Boss DD-3 repair. circuit board
Boss DD-3 circuit board

When played it seems the select knob has trouble changing from 200mS to the 800mS setting.

/Krister

ProCo Rats repair

Got two Rats of different generations on the bench for repair. The v2 to the left, not working at all. The other one did not reach unity gain.

ProCo Rat
ProCo Rats
ProCo Rat
ProCo Rats guts

I had to replace a malfunctioning jfet source follower on the output stage on the old Rat.

ProCo Rat
Non working jfet transistor

The other one had already been messed with. There were several copper traces on the circuit board that had to be mended, the opamp was burnt and wires not connected. Managed to bring it back to life again.

ProCo Rat
ProCo Rat V2

/Krister

Morley Bad Horsie VAI-1 repair

Got this one in for repair

Morley Bad Horsie VAI-1
Morley Bad Horsie VAI-1

Led would not lit at and it did not pass any sound. Opened it up and took some voltage readings. It did not get any coltage due to a bad battery clip.

Morley Bad Horsie VAI-1
Morley Bad Horsie VAI-1 circuit board

After replacing the battery clip it powered up but the led L1 would not lit. Turns out the led was damaged. Had it replaced and adjusted so the circuit would go into bypass mode when the foot is of.

Morley Bad Horsie VAI-1
Morley Bad Horsie VAI-1 L1 replaced

I like the way that the bypass circuitry is built. Never seen a led/ldr combo used with a hex inverter to control the switching fets, works fine on a wah pedal.

Also fixed some new screws for the bottom lid, the old ones where missing.

/Krister