24 Sep
2009
24 Sep
'09
4:45 p.m.
From: "Mike Ross"
4. The big 'gotcha' appears to be
ferroresonant PSUs. I knew those
would be a problem, but I must admit I didn't know DEC used them.
OK, so we've been told the RX01/02 is ferroresonant. Think carefully
folks - are there any other DEC PSUs that use ferroresonant
transformers? I'm thinking mostly about logic PSUs from early
pdp-8/12/15 to later 11s - 11/34, 11/73, pdp-8a etc, but any data
on peripherals which used ferroresonants would also be welcome!
I know the 8/i uses a 704 ferroresonant supply, and I'd guess most
PDP-8 cpus of that vintage or earlier. I'm unsure about the 8/L's
718 power supply. (Normally there'd be a 50Hz variant described,
but I don't see one, but I don't have a proper schematic for the
supply, either.) The PDP-12 uses a 724 power supply, which also
has a resonator. The PDP-8/i and PDP-12 seem have a resonating
capacitor supplied with the transformer for the intended configuration,
so it may suffice just to change the wiring or the capacitor. The
8/a used a supply which has a different transformer part number in
the 50Hz version.
Vince