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SERVICING
26
These capacitors have a 15,000 ohm, 2 watt resistor wired
across its terminals. The object of the resistor is to discharge
the capacitor under certain operating conditions, rather than
having it discharge across the closing of the contacts within
the switching device such as the Start Relay, and to reduce
the chance of shock to the servicer. See the Servicing Section
for specific information concerning capacitors.
RELAY, START
A potential or voltage type relay is used to take the start ca-
pacitor out of the circuit once the motor comes up to speed.
This type of relay is position sensitive. The normally closed
contacts are wired in series with the start capacitor and the
relay holding coil is wired parallel with the start winding. As
the motor starts and comes up to speed, the increase in volt-
age across the start winding will energize the start relay hold-
ing coil and open the contacts to the start capacitor.
Two quick ways to test a capacitor are a resistance and a
capacitance check.
S-15A RESISTANCE CHECK
WARNING
1. Discharge capacitor and remove wire leads.
WARNING
DISCHARGE CAPACITOR THROUGH A 20 TO 30 OHM
RESISTOR BEFORE HANDLING.
Capacito
r
Volt / Ohm
Meter
TESTING CAPACITOR RESISTANCE
2. Set an ohmmeter on its highest ohm scale and connect
the leads to the capacitor -
A. Good Condition - indicator swings to zero and slowly
returns to infinity. (Start capacitor will bleed resistor will
not return to infinity. It will still read the resistance of the
resistor).
B. Shorted - indicator swings to zero and stops there -
replace.
C. Open - no reading - replace. (Start capacitor would read
resistor resistance).
S-15B CAPACITANCE CHECK
WARNING
DISCHARGE CAPACITOR THROUGH A 20 TO 30 OHM
RESISTOR BEFORE HANDLING.
Using a hookup as shown below, take the amperage and volt-
age readings and use them in the formula:
Capacitance (MFD) = 2650 X Amperage
Voltage
15 AMP FUSE
Volt / Ohm
Meter
AMMETER
TESTING CAPACITANCE