Ленинград-1 (Leningrad): Part 3 (Powering on)

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Australia The Clueless Engineer
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Published on ● Video Link: https://www.youtube.com/watch?v=CgU3VRw-zEI


Duration: 15:50
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Before I could try powering it on ... had to make cables.

Made up a new power cable with banana plugs so I could power it from my bench supply, and also a new RGB cable. Both ports on the machine are 5-pin DIN.

The pinout for the power supply is:

Pin 1 = +5VDC
Pin 2 = ground

The pinout for the RGB output is:

Pin 1 = blue
Pin 2 = ground
Pin 3 = red
Pin 4 = green
Pin 5 = synch

And ... the machine booted but with garbage. Draws about 700mA at 5V.

But ... accidentally wiggling some of the keyboard wiring made it boot to the standard ZX Spectrum screen ... "(c) 1982 Sinclair Research Ltd". The keyboard also worked.

So it works ... but needs some TLC on the wiring to get it stabilised. Not sure about the keyboard - don't know if I can salvage it, i.e. get it working decently as it's pretty horrible ...

One thing occurred to me ... what about audio output? There's no speaker/buzzer on the board so it must rely on something external via one of the DIN ports ... ? Maybe the DIN between the power and the RGB that has three wires, including ground on pin 2?

#ZXSpectrum



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