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Transcendent T2000 Synthesizer

A sort of a wet dream, the very simple but also very competent T2000 synthesizer, describes in ETI in 1978 and
available as a kit from Powertran.

The machine had just one VCO but was still capable of producing a lot of great sounds.The features are described in the articles below.

I have been working on cloning the original synthesizer for many years. The first notes about the idea was made in 2018 but it wasn't until Fall 2021 I seriously took a firm grip on this project and went ahead

I used the PCB layout from the articles as a backdrop in my PCB-program - Sprint-Layout 6.0 and just laid out the traces on top and successively made necessary adjustments and modifications.

First I hade to make the board shorter as the program only accepts boards up to 500mm - that was rather easy done. Next I made the board 2-sided with all empty space as a ground plane (hope that works fine).
As I couldn't find the kind of slide switches used in the original I picked the kind used in the Concertmate MG-1, bought cheaply from China (links below) and made adjustments accordingly.
Other modifications was changing the layout for trimmers and changing from transistors BC182/212 to 2N3904/06. Instead of the odd combination of resistors making up the temperature compensation I went for a simple single PTC, 1K resistors and placed them closer to the CA3086s.
Finally I tried to make notes on the board to help find the correct potentiometers and trimmers.

When done, I triple-checked the board to the schematics, and shipped the gerberfiles to JLCPCB ordering a set of 5 boards in purple (the fashion color of this year). Unfortunately,

SCHEMATICS

The ETI articles with full info (pdf).

GERBER FILES

Gerber and drill files zipped

 

PHOTOS

The diagrams I had to work with:

 

Part of the work in Sprint-Layout (green - solder side, blue - component side

 

Final result and the build process:

 

The potentiometer exles are too short and I have to fix that. Got an idea.

 

 

Here's my keyboard and the size is perfect for the board. There's room for MIDI-ins/outs to the left and Power ON/OFF and headphone connector to the right

 

 

As my keyboard has 41 keys whereas the original had only 37 I think this will solve the problem with the 4 extra keys. Still have 24R7 resistors in the chain, but adjust R10 so the total resistor in the loop is unalterted. That should give the required voltage/key drop.

 

 

Checking for shorts between the +12V, GND and -12V connectors revealed a short between GND and -12V.

 

 

It took me some time before finding the error. I did not add the distance between pads for a cap and the ground planes. Fixed it! Not nice but fix'd.

 

 

(random) LINKS

T2000 On Vintagesynth

T2000 On Patchstorage

T2000 on Audiofanzine

T2000 On Midierror

T2000 On Sale At Reverb

T2000 on Gearspace

T2000 Modified at Cykong

T2000 On Matrixsynth

T2000 On Studiorepair (pics)

T2000 On Syntaur

Telefunkian's YT videos

Introducing the Powertran Transcendent 2000

Refurbishing the Powertran Transcendent 2000

Repairing the Powertran Transcendent 2000

Calibrate The Powertran Transcendent 2000

Modifying The Powertran Transcendent 2000

Other YT videos:

SynthMania: The Powertran Transcendent 2000 - classic Joy Division synth

LookMumNoComputer: The POWERTRAN Transcendent 2000

2-pole 2-way switch

2-pole 3-way switch

JLCPCB