25-02-2013, 08:20 PM
The collection is slowly getting underway here much to SWMBO's disgust. On a job lot with a bundle of cassettes, on 1982 vintage ZX Spectrum with dead flesh keys and a series 2 motherboard. The bezil was lifting on one corner, usual as it's only held down with double sided tape. Little in the way of wear, the bezil info was clean and tidy, overall a good example of early 80s computer kit.
Lid off, not much to touch in there, all intact, no burn damage but a lot of mods carried out by the factors in order to correct some designed in issues. At least one flying lead from an additional ZTX transistor and a couple of resistances changed from the original spec.
The power supply was unhappy, the usual insulation wear on exit from the PSU body. This had to be cut out and be re-terminated. I don't have a grommit that size so it's one for the shopping list. Plugging in, the transformer buzzed noisily but slowly settled down to a gentle buzz with use.
Plugging in the computer, was rewarded with the usual 1982 Sinclair Research sign and little else. A whole tranche of keys running downwards from 6 amd 7 were non operational. Usual problem with computers of this age, the membrane under the keypad had become brittle with age and the tracks had cracked in numerous places. A replacement membrane made of UV resistant materials was sourced from Sintech for the paltry sum of £9.95 inc post and packing, and arrived within two days via second class post. The new membrane is a lot thicker compared to the old unit, and plugs firmly into the molex connectors without distorting or cracking. Lid on, power up and wullah, one working keyboard.
Usual tests as per the Thorn Datatech service manual were carried out, brains and memory fully intact. One tiny issue, the white paper was more yellow tinged than normal and no amount of tweaking woul get it to whiten out. Turns out that only one of four resistors on the video mods list had actually been carried out so one for a later day when I'm bored.
Lid off, not much to touch in there, all intact, no burn damage but a lot of mods carried out by the factors in order to correct some designed in issues. At least one flying lead from an additional ZTX transistor and a couple of resistances changed from the original spec.
The power supply was unhappy, the usual insulation wear on exit from the PSU body. This had to be cut out and be re-terminated. I don't have a grommit that size so it's one for the shopping list. Plugging in, the transformer buzzed noisily but slowly settled down to a gentle buzz with use.
Plugging in the computer, was rewarded with the usual 1982 Sinclair Research sign and little else. A whole tranche of keys running downwards from 6 amd 7 were non operational. Usual problem with computers of this age, the membrane under the keypad had become brittle with age and the tracks had cracked in numerous places. A replacement membrane made of UV resistant materials was sourced from Sintech for the paltry sum of £9.95 inc post and packing, and arrived within two days via second class post. The new membrane is a lot thicker compared to the old unit, and plugs firmly into the molex connectors without distorting or cracking. Lid on, power up and wullah, one working keyboard.
Usual tests as per the Thorn Datatech service manual were carried out, brains and memory fully intact. One tiny issue, the white paper was more yellow tinged than normal and no amount of tweaking woul get it to whiten out. Turns out that only one of four resistors on the video mods list had actually been carried out so one for a later day when I'm bored.
