PDP 11/70: MK11 memory crate, M9312 cards, and wiring...

[Mike Cesari]

On Oct 10, 2004, at 2:01 PM, Jules Richardson wrote:

>
> Heh - I was staring at DEC engineering drawings for hours and it was
> giving me a headache! I need to look at all the info for the memory
> crate though as the CPU still isn't happy (the run lamp's permanently 
> on
> and we can't halt the CPU or toggle any data in from the front panel).
> All cards look to be OK in the CPU though, but I suspect there may be a
> problem with the memory...
>

Jules,

The run lamp on can also indicate a power problem of one kind or 
another.
Check AC and DC LOW (the purple and yellow wires). If either is low, 
there
is an issue. I bet the CPU microcode address is 0200, too.

If you already haven't, terminate the unibus at the end of the backplane
in the CPU cabinet.

Mike