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Pets and filter caps - magic smoke worry??

mbliss11

Experienced Member
Joined
Oct 31, 2022
Messages
272
Location
Maryland
I have had my CBM 2001 for about a year and a half. Picked it up locally non working but turned out to be bad solder joints on the crt board. Has been working great ever since. I power it up once a week and run a demo on it. Watched an Adrian video this morning and he said that his pet had let out magic smoke from its mains filter cap from just being plugged in (wasn’t turned on just connected to outlet). I had no clue that these had known failing filter caps in them.

Have seen pictures online showing the filter cap on some 8032 models. Appears to be a metal cylinder close to the transformer. Are these on all pets? I popped mine open to see if one is in there and if it is it would be behind or underneath the transformer and would need to take apart further.

Are these on all pets? Should we be cracking these open and getting them out?
 

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So I took the board out and popped the plate covering the fuse and ac cord slot. I don’t think there is a filter cap in my pet. Does this look stock?
 

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Multiple appliances (not just the PET) had filter cap units applied across the incoming line voltage. Many were three wire types which had a capacitor from phase & neutral to ground called Y capacitors, of the X type are connected across phase and neutral, though if they are placed before the power switch, they were often in metal IEC connector bodies that contained them. The usual wiring in a unit, is that the phase wire from the standard connector or plug, passes to the fuse first, then the switch and then everything else after that including the power transformer primary and any filter caps. So it is more unusual to find these caps smoking when the appliance's power switch is off.

Unfortunately they were of the metallized paper variety. Eventually they fail and start to become conductive. They then heat up, consuming energy and eventually go into a full blown melt down mode and smoke out the house. If you find them, you don't have to replace them, just discard them is the better option. Many of the replacement capacitors tend to go the same way, if you wait long enough.
 
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