08-08-2015, 04:00 PM
Second foray into the world of Commodore (that's another story) and a Commodore 64 computer in average condition. Early 80s plastic meant a few nicks and bangs but nothing out of the ordinary that would condemn the machine. For a change, somebody had wired the plug correctly although the 13amp fuse would have to go.
Plug in and nothing, zilch, no power on LED illuminated. Interesting that the telly would tune into where the carrier should be even with as was found out later only half the PSU working. The 64s PSU came in two types, the beige cheese wedge shape of the early 80s, to be replaced by the later black or white soap bar shape. A quick test with a meter revealed all, the 9vac supply was there and that supplies the SID chip directly which explained why a carrier was locked onto during television tuning, but the 5v rail was completely missing. Onto T'Net for a circuit diagram and a moment of abject disgust. Commodore in order to keep the prices down had cheapened the PSU by using a power transistor / resistor arrangement which in operation would run uber hot. OK, not so bad, the PSU was one of the later soap bar ones so after much grunting and moaning got the back off the PSU to find that the idiots at Commodore had encapsulated the whole lot in epoxy which meant that the PSU instead of running uber hot was in operation doing an impression of the surface of the sun. No wonder the PSU had gone pop, and to rub it in there was a distinct possibility that before the 5v rail went down, it would have climbed up to 8v and taken the memory chips on the computer.
OK, up for a challenge, but not in this case. Plenty of spare memory chips if it came to it but no PSU but luckily managed to source a replacement on the net which took a couple of days to turn up. Again, plug wired correctly, and this one had all the supply rails in the right place so plug in and wullah, a thankfully working correctly C64.
Inside the 64, fluff balls but reasonably clean. This was a late build unit in that the shielding around the gubbins was of the foil coated cardboard rather than the metal in the earlier offerings, which belies the financial issues the Commodore group were going through at the time. A blow out with an airline of both the main board and the keyboard panel elected a cloud of dust and thankfully no food residue. Finally, the keyboard was cleaned down with antiseptic wipes, you never know whose hands have been on what keyboard and what they have been scratching, so I make it a point to totally sanitise such items.
Pictures of PSU circuit, computer and my daughter testing the final product, playing Jack The Nipper.
Nice machine, loads games from the 1541 tape player quite well. Decent collectors item this one.
Plug in and nothing, zilch, no power on LED illuminated. Interesting that the telly would tune into where the carrier should be even with as was found out later only half the PSU working. The 64s PSU came in two types, the beige cheese wedge shape of the early 80s, to be replaced by the later black or white soap bar shape. A quick test with a meter revealed all, the 9vac supply was there and that supplies the SID chip directly which explained why a carrier was locked onto during television tuning, but the 5v rail was completely missing. Onto T'Net for a circuit diagram and a moment of abject disgust. Commodore in order to keep the prices down had cheapened the PSU by using a power transistor / resistor arrangement which in operation would run uber hot. OK, not so bad, the PSU was one of the later soap bar ones so after much grunting and moaning got the back off the PSU to find that the idiots at Commodore had encapsulated the whole lot in epoxy which meant that the PSU instead of running uber hot was in operation doing an impression of the surface of the sun. No wonder the PSU had gone pop, and to rub it in there was a distinct possibility that before the 5v rail went down, it would have climbed up to 8v and taken the memory chips on the computer.
OK, up for a challenge, but not in this case. Plenty of spare memory chips if it came to it but no PSU but luckily managed to source a replacement on the net which took a couple of days to turn up. Again, plug wired correctly, and this one had all the supply rails in the right place so plug in and wullah, a thankfully working correctly C64.
Inside the 64, fluff balls but reasonably clean. This was a late build unit in that the shielding around the gubbins was of the foil coated cardboard rather than the metal in the earlier offerings, which belies the financial issues the Commodore group were going through at the time. A blow out with an airline of both the main board and the keyboard panel elected a cloud of dust and thankfully no food residue. Finally, the keyboard was cleaned down with antiseptic wipes, you never know whose hands have been on what keyboard and what they have been scratching, so I make it a point to totally sanitise such items.
Pictures of PSU circuit, computer and my daughter testing the final product, playing Jack The Nipper.
Nice machine, loads games from the 1541 tape player quite well. Decent collectors item this one.
