Tag Archives: spectrum

ZX Spectrum+ 48K

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This is a Sinclair ZX Spectrum+ 48k home computer released in 1984.

The Spectrum+ 48k is practically identical to a standard Spectrum 48k, with two differences :

1, The new QL-style case.

2, A reset button.

It has RF output via an RCA on the backside.
But since i want to use composite video, i will have to do a mod. 🙂

The keyboard membrane have been replaced with a new one.

The 7805 +5v power regulator was also changed to a TSR 1-2450 switching regulator that does not generate any heat to keep it cooler.

It works perfectly. 🙂

ZX Spectrum 48k update #2

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The new keyboard membrane arrived from the UK.
I replaced the membrane and it worked perfectly.

I also replaced the 7805 5v power regulator with a TSR 1-2450 switched regulator.
This one does not produce any heat, så the temperature inside the Spectrum should now be very much cooler.

I also hooked up the Interface One adapter that allows connecting a microdrive.

And on the rear of the Interface One i connected the Multiface One, that allows saving programs to microdrive or tape.
It also allows to pause a game and enter a poke that for example gives endless lives in a game. 🙂

Tested it all, and it works as designed.
Perfect, next project… 🙂

ZX Spectrum 48k update

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I got the capacitors in the mail, and replaced them all.

Apparently, the positive end of the C46 capacitor was wrongly marked on the circuit board.
I documented the capacitors on this issue two motherboard, for future use. 🙂

When tested, the image still had that yellowish tone, so it was time to adjust VR1 and VR2.

I used my oscilloscope attached to the composite wire to get the noice level as small as possible.

Much better, now it is white as it should be. 🙂

Can’t test anything else right now, because i am waiting for the new keyboard membrane from UK to arrive.

To be continued. 🙂