MicroVAX 3100 Model 95 Ripple

[Rob Jarratt]

Hello,

 

I have recently been trying to improve the ripple on the output of my
MicroVAX 3100 Model 95 PSU because occasionally it would fry a memory
module. I replaced a bunch of capacitors, some of which had started to leak.
However, the ripple does not seem much better. There is a scope trace here: 

 

https://rjarratt.files.wordpress.com/2020/05/microvax-3100-model-95-psu-ripp
le-after-re-capping.png

 

Ch1 is the 12V output and Ch2 is the 5V output. I had an old RD53 connected
as a dummy load. It is possible that the memory was breaking because of
occasional spikes that are worse, but I don't know. Does that seem OK?

 

Thanks

 

Rob