Hi all,
I bought a Sinclair ZX81 on a garage sale some days ago for around 12 USD as a non-tested item as the guy said he had no wires to even try and run it. I have a couple of RF cable kicking about from my Atari 2600 and ZX Spectrum, so I have this basis covered.
According to the manual LINK it takes 9V 700mA unregulated (I'm not sure what it means) 3.7mm jack power supply. I have a 9V DC 1A jack power supply I bought for the Atari (it's not an original one - a unbranded one) and I tried to use it, but to no success. Manual tuning my TV same as with Spectrum and Atari, and no signal.
I was wondering if maybe the power supply is not up to spec? I was thinking that maybe 1mA is too much to power it up? But I went online to look for an unbranded ZX81 power supply and they are running 2A so I'm not sure what's going on here.
Is it busted? Or should I get one of those unbranded power supplies that say they are made for ZX81 to test it?
Thanks :)
1A might be too much. You’ll also need to ensure the polarity is correct. There should be a label, usually co-located with the serial number, which states the input and polarity requirements of the DC plug.
So if I already connected it, does it mean it ruined the computer?
They are selling replacements that are rated 2A:
It really depends on the internal tolerances. If you are familiar with basic circuitry and the use of a multimeter, you can check for initial power continuity.
Otherwise, using the correct amperage and polarity power supply will be the easiest check.