On 2012-09-22, at 18:22, Nicolas Welte wrote: > It's also interesting, that at least the first C64 PCB came with only one of the +5V pins wired internally. There is a note in the service manual that a wire is to be installed to connect the second pin. Why this was done is a mystery to me, since all C64 power supplies that I know, use only a single +5V pin. Even the power supplies that have all 7 pins physically installed, have only a single +5V pin connected. The PSUs indeed used one pin only but it could be any of the two. Before They started to make the plugs with four pins only [*] I encountered PSUs with +5 supplied to either pin 4 or 5 (with no apparent pattern/rule). Thus my guess is that someone in Hong Kong (or wherever those PSUs were made at the time) might have mixed the pins as looking from the other side of the plug and then the PSU was no longer compatible. So after first of such batches, dudes at CBM decided to wire up both pins symmetrically so that no matter how the manufacturer looks at the plug, it will still work. For pins 6 and 7 there was no problem as they were already both symmetrical and AC ;-) * - and cheap plugs (with poorly pressed notches on the round shield), which many people managed to plug in differently than intended, sending half of the computer to the land of eternal hunting... -- SD! Message was sent through the cbm-hackers mailing listReceived on 2012-09-22 20:00:10
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