3 Dec
2003
3 Dec
'03
10:59 p.m.
These are oilfilled AC capacitors. Not an electrolytic
capacitor. They are
usually used together with the motor. Phase-shift capacitor for example to
generate a second phase on a single phase system.
Do no replace with an electrolytic capacitor. Electrolytic capacitors are
DC
only.
Old DEC equipment contain a lot of them. It is not uncommon to find such
capacitors with PCB (Polyclorinathed Bifenyles, if my speeling is correct)
in them. Take care if one of these goes into smoke. Burnt PCB produces
really lethal dioxines.
Hmm...Doesn't look oil-filled to me; more like a cream-colored paste. Looks
just like an electrolytic which has blown crud out through the safety vent,
which has then hardened over the years into a crust. Under the crust is a
cream-colored substance with a texture like hardened toothpaste.
I do know that motor start and motor run are different and incompatible.
This one is connected to the coils driven by a G848, if I understand the
TU56 drawings correctly. The G848 drawing shows it being driven
bi-directionally to "motor supply", so you could be right about it not being
polarized, though I also thought I read a faint "-" next to one of the
solder tabs.
How would I tell the difference between a motor-run and a motor-start cap by
looking?
Thanks!
Vince