Sinclair ZX Spectrum

I cannot remember when I got this ZX Spectrum from a friend. He described it as "damaged and not repairable", so he wanted to dispose it, but then donated it to me.

It turned out that the voltage converter was broken, due to a coil with melted insulation. This damage usually occurs when an expansion is removed from the ZX Spectrum while it is still powered on.

I repaired the damage. For the case, I used the plastic shells of my own ZX Spectrum, but used a new membrane and faceplate. The machine now looks almost as new, with only minor scratchmarks.

Configuration

• Built: 1983
• Mainboard: Issue Two
• CPU: Z80A
• ULA: 5C112E-3 (date code 8320, made in UK)
• RAM: 48KB
• Composite mod

Known Issues

• Output signal has a yellow tint even after calibration. Colors are completely off. This may be due to the back porch bug of ULA type 5.

Restauration Works

• Restauration was carried out in May 2021
• Modified the modulator to create a composite signal, reversible
• General cleaning
• Repaired a coil damage: Wound new coil, preemptively replaced TR4, TR5, D16
• Replaced damaged CPU
• All electrolytic capacitors replaced with new, long-live types
• Replaced broken original keyboard membrane
• New replica faceplate in standard color (the old was scratched and dented)
• Replaced 7805 with Traco Power TSR-1 DC/DC converter, removed heatsink
• Calibrated video output