gwiley
Experienced Member
Does anyone remember this post? There was a post somewhere on the forum about replacement parts for the AC input common mode filter capacitors, or Y-capacitors, or "bathtub" capacitors, in an older DEC machine. I think it was by someone who posts often, and they recommended that the filter capacitor module be replaced because it's prone to failure. There was also a link to a specific replacement part on Mouser or some other parts distributor, which is what I'm looking for. The thread might have been related to a PDP-8/L or 8/I, but it could have been about some other DEC chassis. The thread topic may have been about something else, but there was a comment about the capacitors with a link to the replacement part. I think the H724 supply in an 8/E may use the same or similar Y-cap, C500 & C501.
I've tried the advanced search function but either come up with nothing or too much.
I think the post might have also mentioned that some rather spectacular failure modes have happened. I'd rather just replace them if parts are readily available, or I could just disconnect them until they've been verified.
Here's a photo & schematic to clarify what I'm talking about. There are a pair of these capacitors in an 8/L which I've not yet connected to AC power.
This is the back side with quick connect terminals to AC hot and neutral. The common point between the two capacitors is connected to the case.
It's C1 and C2 in this schematic
I've tried the advanced search function but either come up with nothing or too much.
I think the post might have also mentioned that some rather spectacular failure modes have happened. I'd rather just replace them if parts are readily available, or I could just disconnect them until they've been verified.
Here's a photo & schematic to clarify what I'm talking about. There are a pair of these capacitors in an 8/L which I've not yet connected to AC power.
This is the back side with quick connect terminals to AC hot and neutral. The common point between the two capacitors is connected to the case.
It's C1 and C2 in this schematic