Vaxstation 400/90 power supply

Brent Hilpert bhilpert at
Mon Mar 23 15:03:51 CDT 2020

On 2020-Mar-23, at 6:56 AM, emanuel stiebler via cctalk wrote:
> I have 4000/90 which behaves funny. It only starts, after switching on
> twice. The first time, all LEDs stay on, flipping the switch off/on, it
> boots happily.
> Any insight?

I've experienced behaviour like this in an Apple-something.
It related to a dead RTC/boot-ROM battery. I figured it out (years ago) but now forget the exact mechanistics, but it was along the lines of the first power-on leaves enough charge in a capacitor for the subsequent power-on to see the RTC/ROM as at least 'valid', albeit not 'correct', if you get my drift.

That's just a suggestion/possibility - I'm not acquainted with the 4000/90 specifically.

More information about the cctech mailing list