Amps and effects
Work in progress
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.
/Krister
JCM 800 2205 dated 1987.
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.
New F & T cap vs old one.
A pair of caps hidden under the circuit board.
Guts after service, only mod is 1 ohm bias resistors added.
/Krister
Received a shipment with parts for a Marshall 2205. Thumbs up for Tube-Town, they sent chocalate with the package!
/Krister
The channel switching mod to the old Siemens 6 S Ela 2427c installed. The optocouplers circuit board found a place.
Another view, on the left is the input jack, switch for channels and a remote jack for channels.
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.
Another view where you can see the new wiring to the old pilot lamp now acting as channel indicator.
/Krister
Laney Klipp100 amplifier after modification. The master volume pot was a mod already made. It now holds a switch for channel selection, a 6,3mm jack for remote channel switching and indicating leds for each channel.
Back of the amplifier. Bias pot, bias measuring points , effects loop with send level pot and a gain switch.
Here’s an image with the channel switching circuit board installed using optocouplers .
A closer look at the gain switch mod and the effects loop.
Here’s an image of the bias pot with measuring outlets and the transformer for the channel switching circuit,
/Krister
This is what’s to be the V2 of the PS-1A clone. It’s got a new main circuit board with onboard in/output jacks.
Here’s the circuit installed in the chassie.
/Krister
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.
Here’s a picture from the bottom of the caps.
Those caps are out of date.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
Addon circuit board for channel switching with optocouplers.
/Krister
A new channel switching circuit board prepared for an old tube amp.
The plan is to fit it in this one.
/Krister
Giving the zeta sound Turtle Clipper an updated circuit board.
/Krister