Sinclair ZX Spectrum

I bought this machine as a bundle of Sinclair hardware in February 2022. It came with the original PSU. It has been stored away for a long time, as it was quite filthy and had a few scratches. It had a label with an inventory date of March 19th, 1985 (removed now).

The computer was untested when sold. The diagnostics showed that it is basically working, but had two defective upper RAM chips.

The keymat was filthy and had a strong smell of moist. I decided to keep the keymat, but use a new standard black replica faceplate.

Configuration

• Built: Early 1983
• Mainboard: Issue Two
• CPU: Z80A
• ULA: 5C112E (date code 8304, probably made in Phillipines)
• RAM: 48KB
• Came with an original PSU with EU plug (cleaned, untested, unrefurbished)

Known Issues

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

Restauration Works

• Restauration was carried out between February and March 2022.
• Thorough cleaning of the case. I also removed a security sticker that had been attached by the previous owner. It was very difficult to remove, and unfortunately left a lot of scratches on the bottom shell.
• The keyboard membrane connector was broken due to old age, and was replaced.
• The faceplate got bent on my attempt to remove it, and was replaced with a new replica one.
• Replaced two upper RAM chips that were reported as faulty.
• Replaced 7805 with Traco Power TSR-1 DC/DC converter, removed heatsink
• Recapping, Composite Mod
• Calibrated video output