J
Joerg
- Jan 1, 1970
- 0
Folks,
This afternoon I took the old HP-4191A apart. Yesterday in the middle of
some measurements it went pop-pop-pop, loud, like firecrackers. I ran
over and turned it off, upon which the popping stopped. An immense
amount of light-gray smoke wafted out and it had an odd stench to it.
The stench lingered for hours.
I can't find any source and upon powering it up the analyzer worked
fine. That was before I changed anything. As if it had repaired itself.
The only thing I could see is a crack in the plastic of the X-capacitor.
Snipped the thing out, measured, has almost 0.28uF capacitance (27% more
than stated) and no leakage current. There is another X-cap and two
Y-caps inside a canned IEC receptacle but those can't be the culprits
because that is on the line side of the power switch.
Is it possible that an X-cap self-heals to the point where you can
barely see a thing, yet release a serious plume of smoke? It is a Rifa
GPF-series film cap 0.22uF/250VAC with all kinds of agency logos on there.
This afternoon I took the old HP-4191A apart. Yesterday in the middle of
some measurements it went pop-pop-pop, loud, like firecrackers. I ran
over and turned it off, upon which the popping stopped. An immense
amount of light-gray smoke wafted out and it had an odd stench to it.
The stench lingered for hours.
I can't find any source and upon powering it up the analyzer worked
fine. That was before I changed anything. As if it had repaired itself.
The only thing I could see is a crack in the plastic of the X-capacitor.
Snipped the thing out, measured, has almost 0.28uF capacitance (27% more
than stated) and no leakage current. There is another X-cap and two
Y-caps inside a canned IEC receptacle but those can't be the culprits
because that is on the line side of the power switch.
Is it possible that an X-cap self-heals to the point where you can
barely see a thing, yet release a serious plume of smoke? It is a Rifa
GPF-series film cap 0.22uF/250VAC with all kinds of agency logos on there.