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Old 17th May 2021, 9:14 am   #30
dave cox
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Join Date: Jan 2009
Location: Bristol, UK.
Posts: 1,677
Default Re: HP 180A Oscilloscope.

The foam is there to improve electrical isolation. This is probably more of an electrical breakdown than an overheat, maybe a crack in the capacitor casing and has 'arced' through the foam. Maybe when it was assembled there was too much pressure in that region - maybe

Fingers crossed, replacing those two parts should bring you closer to a working scope.

When you replace the HV cap, be sure to carefully clean the surroundings with alcohol - especially anything that appears to have blackened. Carbon / soot is very conductive! Remove the existing foam, it should be replaced but I'm at a loss for a replacement at the moment, maybe Andy (DA) or David (factory) knows of something that could be used ...

BTW, it was very good that you followed your nose!


Last edited by dave cox; 17th May 2021 at 9:31 am.
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