Didaktik M: Part 1 - First Look
30This 1990 model Didaktik M ZX Spectrum clone appears to be working - just need to figure out the video output. It was built in Skalica, Czechoslovakia post Velvet Revolution on the Slovak side (pre-breakup).
The power brick supplies a regulated +5V and an unregulated +12V (measured at +28V under no load).
It uses edge connectors (à la Enterprise 64/128) ... and not DIN or DE9 ... for a Sinclair and a Kempston joystick ... mmmkay.
I found some schematics here for the machine:
https://billy48.speccy.cz/hardware/schematics/didaktik_m_90_schematic.png
It includes modulated and baseband composite video output ... looks like the composite video comes out of the LM1889 via an emitter follower ... where the +12V from the PSU is used. So I need to measure the "+12V" to see if it is really +12V under load, and not +28V.
As an alternative I could wire up another DIN-to-DIN power cable to use my Mean Well power brick that provides a regulated +5VDC and +12VDC.
The board will be a pain to remove from the case if any soldering work is required due to the DIN & TV sockets.
The keyboard seems a little unforgiving - you have to strike the key dead centre ... if you're a little off-centre then the key won't go down.
I should get video output working in part 2 ...