MB-6582 J1 Ground pin?

[Snoozr]

Hello,

Sorry for the basic question which was not able to be cleared up after lengthy scrutinizing of the PCB schem and forum searching. I am having a bit of difficulty determining which hole of J1 corresponds to ground.

I have spliced a black (12V) C64 plug onto a grey (9V) C64 PSU. The original black 7-pin DIN was:

1.......7

..2...6..

3...4...5

.........

..8..9...

as viewed from upside down (sorry - that's the way I made my notes) and according to this notation 6 is +5V and 4 is ground.

On the MB-6582, 2 and 6 are bridged whereas there is no trace leading to 4. There is also no trace leading to the pin labeled GND on J1A.

I'm probably missing something extremely basic but my very limited knowledge suggests that the electricity has to "go out" somewhere, hence I need a connection to ground.

Thanks and happy new year :)

[Wilba]

There are no traces to GND because there is a ground plane.

It's the middle pin of J1.

I'm curious to know why you are "splicing" a new plug onto the C64... also, there's no such thing as a "12V" and "9V" C64 PSUs, they all have the same output (9V AC + 5V regulated DC), although they can have different power ratings and sometimes the 5V is on a different pin (hence the bridge you seen between two pins, to allow 5V to be supplied on either of those pins).

[Snoozr]

Thanks for clearing that up -- I also looked up ground plane and got to learn something as a side bonus :)

As for the splicing, I've purchased 4 faulty black PSUs on ebay, then one good grey one. The original grey receptacles were very difficult to locate, and of course the grey one's connector doesn't fit the circular 7-pin MB-6582 receptacle. I also didn't want to buy a grey C64 solely for salvaging a receptacle because I would have no use for the rest of the C64. The best solution for me was to splice.

Thanks again for fixing me up.