Work in progress

Some images from the workbench.

Mounting hardware in a Lady Dirt tube pedal.

Zeta Sound Lady Dirt high voltage tube pedal
Lady Dirt high voltage tube pedal

The circuit board of the Bull pedal. There’s silicone diodes clipping and in the front of the image you ses two germanium AA144 diodes. There’s three BC184 transistors and one 2N3904. Posted earlier here.

Bull pedal
BULL circuit board

Just had to take this picture. A cap from the 1950:s vs a modern one, same uF and voltage rating.

vintage vs new capacitor
Cap vs cap

Here’s a gut shot from the new prototype of the Maestro PS-1A clone.

MaestroPS-1A Clone zeta-sound
Maestro PS-1A clone.

/Krister

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

fOXX Tone Machine

How about a clone of a fOXX Tone Machine. First prototype from zeta-sound, including germanium diodes, stompswitch for octave and bypass, DC-Jack and battery space. Hosted in a 1590B type of enclosure.

fOXX Tone Machine
fOXX Tone Machine guts

/Krister

Maestro PS-1A V2

Video and pictures of the V2 zeta-sound clone of the Maestro PS-1A phase shifter.

Mainly changes made in the main circuit board layout , allowing the stompswitches a bit more centered and using onboard in/output jacks. The speed selector circuit works the same as in V1, tap the switch and change the speed through three presets. Blue -> Slow, Green -> Medium, Red -> Fast.

Stepping through the three speeds.
MaestroPS-1A V2 Clone zeta-sound
Maestro PS-1A V2 clone
MaestroPS-1A V2 Clone zeta-sound
Maestro PS-1A V2
MaestroPS-1A V2 Clone zeta-sound
Maestro PS-1A V2
MaestroPS-1A Clone zeta-sound
Maestro PS-1A V2 guts
MaestroPS-1A V2 Clone zeta-sound
Maestro PS-1A V2 circuit board

/Krister

Marshall 2205 service

JCM 800 2205 dated 1987.

Marshall 2205 service
Marshall 2205

Since about 30 years old and last known service dated from 1998 with new output tubes, it now got all them electrolytic caps changed and a new pair of EL34 power tubes.

Marshall 2205 service
Last known service note

New F & T cap vs old one.

Marshall 2205 caps
caps

A pair of caps hidden under the circuit board.

Marshall 2205 caps
caps

Guts after service, only mod is 1 ohm bias resistors added.

Marshall 2205 service
Marshall 2205 service

/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

Seimens tube amp mod

The channel switching mod to the old Siemens 6 S Ela 2427c installed. The optocouplers circuit board found a place.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c guts

Another view, on the left is the input jack, switch for channels and a remote jack for channels.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c guts

I removed the guts from the pilot lamp and installed the channel indicating leds in it. We can see the two new pots installed, a clean volume pot and a mids pot.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c front

Another view where you can see the new wiring to the old pilot lamp now acting as channel indicator.

Siemens 6 S Ela 2427c
Siemens 6 S Ela 2427c top

/Krister