FW: [Boatanchors] CAPACITORS

[GGLL]

	Brian, that capacitor may be 4 uF not 4 pF ? (at least, that's what I'm used 
to find here as for motor starting).
You have two ways, the simpler is measuring it with a capacimeter, which I
guess you don't have, the other with an analog ohmmeter (perhaps at 10x or
100x range, you look for a charge process which makes the needle jump to some 
degree when you connect the capacitor across the ohmmeter's tips, then return 
to the infinite resistance; depending the scale selected, the higher the uF 
value the higher this jump; if it also measure some low permanent resistance, 
it's time to change it) one could check for "activity" and comparing against 
another good one to get an idea.
If you have a similar value (voltage rating is not important) good capacitor 
you could have an idea of this "activity" process, by comparing both.
Disconnect at least one lead of the capacitor to check.

Best regards
Guillermo - LU8EYW.

brian goldsmith escribió:
> 
> -----Original Message-----
> From: W4AWM at aol.com
> 
> 
> This may be a bit off the subject, but can anyone tell me how to check a 
> motor starting capacitor without substitution. I don't have a spare.
> Capacity is 
> 9pf @ 250VAC.
> 
> 73 and thanks,
> 
> John,  W4AWM
> 
> ***** It almost certainly is NOT 9 pF,more likely to be 9 microFarads (or 9
> uF).
> Simplest method of testing is to use a high voltage DC supply from an old
> radio capable of providing at least 350 Volts,use two 220V series connected
> low wattage incandescent lamp to limit the current ,then charge the
> capacitor up.Watch the lamp,if it goes out,most likely the cap is OK,if the
> lamp stays illuminated to even a slight degree then the cap is leaky.If you
> do not observe any light at all from the start of the charging then the cap
> is either fully charged (discharge it with a resistor,never a direct short)
> or it is open circuit.
> 
> Brian Goldsmith.
> 
> 
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