Ah so they are - I was misremembering those as also being RIFAs I recently serviced a 1980's oscilloscope (Philips possibly?) that had RIFA class Ys too. I tend to call them all RIFAs - they also tend to crack and go bad but I've not had any go smoky yet. I suppose if they did they would trip the RCD?The leakages are from the Y capacitors, these are the large ceramic capacitors...The leakages are the rifa's. I would clean, check and tighten the earthing points in the psu iirc they're all just smallish machine screws and star washers on the beeb. That's the most likely point of deterioration from the earth resistance point of view?
I usually measure my setups for ground loop (including all the distribution strips) and haven't had any bother with beeb molded on plugs yet but I will re-measure now after reading this...if I can re-borrow a tester.The continuity from the earthing points to the ground wire is less than 0.01R. When I cut the plug off and replace it, I get less than 0.01R on the plug in ground loop tester.
As I re-cap the PSUs in all the BBCs, I take care to ensure the connections are solid. I only used a multimeter on continuity to make sure the earth pin had some form of continuity to the chassis and the 0V rail. It has become apparent that this is not good enough...
Did you keep the old plug - it would be interesting to find out what the failure mode was
D
Statistics: Posted by dominicbeesley — Thu Mar 27, 2025 11:26 am