Memory Voltage on MicroVAX II

tony duell ard at
Sat Dec 5 13:12:22 CST 2015

> There seems to be a spike on the 12V supply, surely that isn't good, even if
> it doesn't affect the memory?

Often a spike on a particular output of an SMPSU is caused by a high ESR capacitor
on that output. It's worth checking them.

FWIW, old DRAMs, up to about 16Kbit size, often used +12V and -5V as well as +5V.
Later/larger DRAMs are +5V only. I doubt you'll find any of the former in a VAX after 
early 11/700-series.


More information about the cctech mailing list