Микрон (Micron) 1.0: A Russian ZX Spectrum Clone (Part 1)
26This particular machine was built in November 1992, in Saint Petersburg (formerly Leningrad) and is serial number 69. It came complete with manuals, a KM-012 television RGB-adaptor daughter board (to add RGB input to your Soviet TV), joystick and power supply. Oh, and the box.
The box proclaims that it's a "ZX Spectrum Совместимый Персональный Компьюер" ... ZX Spectrum Compatible Personal Computer.
Overall it is quite well built - nice and solid. It does have a membrane keyboard though, a first in the Eastern Bloc Speccy clones I've looked at.
In this first part we check out the power supply, open up the machine and build an RGBS + audio cable to test if it works (yes, it does!).
The PSU appears to be pretty good quality and is marked as 220VAC, 50Hz input and 9VDC, 0.5A output ... however it is simply a toroid and a pair of fuses ... at 240VAC it actually outputs around 12VAC ... certainly not DC. Again, the use of a DIN (non-standard 5-pin in this case) is weirdly excessive ... the Soviets never seem to use Philips head screws nor 2.1mm DC sockets ;)
The rectification and regulation to 5V are actually done inside the machine.
It is mostly Soviet-era parts apart from the Z80 which is a Western part (ST Microelectronics).
The machine doesn't contain a beeper internally, relying on the 7-pin DIN "TV" output for mono audio.
On boot we are presented with the following copyright screen:
"MIKRON 1.0 St-Petersburg 1992"
I'm not sure if the documentation is otherwise available. In any case, I'm uploading it to Archive when I can. So far:
Schematic of the machine:
https://archive.org/details/mikron-1-schematic
Manual & schematic of the KM-012 RGB-adaptor board:
https://archive.org/details/mikron-1-km-012-television-rgb-adaptor-manual
Part 2:
https://youtu.be/k0_ehywb-ps
Part 3:
https://youtu.be/EXddIFGi8Cg
Part 4:
https://youtu.be/3O6pupkXCDo