Dc Ammeter (M1); Filter Capacitors (C1 / C2); Internal Wiring - HindlePower SCRF SERIES Operating And Service Instructions

k. DC Ammeter (M1)
1. The charger DC ammeter is connected in series between the charger output and battery. If open it
will indicate zero, or if shorted, it will also indicate zero. First be certain the connections are tight. If still no
indication, turn CB1 and CB2 breakers to OFF, disconnect the charger ammeter (and/or shunt) and
substitute a precision ammeter of suitable range. Be certain to make solid connections; clip contacts may not
carry sufficient current, or may make poor contact and cause the reading to be inaccurate.
2. A reverse-scale indication of the meter indicates the charger is inoperative or internally shorted,
and that the battery is discharging through the rectifier, or that the meter leads have been reversed. Turn CB1
and CB2 to OFF and check wiring and meter connections. Then check meter operation, using a 1-1/2 Volt
D-cell as the power source. Momentarily touch the D-cell terminals (with proper polarity) to meter terminals
and observe meter deflection.
m. Filter Capacitors (C1/C2) - (filtered chargers only)
NOTE: Capacitors C1 and C2 may consist of one or more parallel-connected capacitor units as
needed by the filtering requirements. C2 normally is used only in chargers with the filtered eliminator
option.
CAUTION: The filter capacitor is on the charger side of the blocking diode (CR2) and is NOT
charged by the battery when CB2 is turned ON. When the charger is turned "OFF" (CB1 opened) the
capacitor will hold a charge until discharged by bleeder resistor (R1). Capacitors C1 and C2 should always
be discharged before servicing in the event the R1 has opened and no longer serves as a bleeder.
1. Before attempting to check the output ripple, it should be determined that in all other respects the
charger is operating normally. Having determined this, the ripple may be checked as follows. Connect a
sensitive AC voltmeter (digital type preferred) to the battery terminals and measure the AC ripple voltage. If
it measures more than 30 milliVolts RMS check the following:
(a). That the battery connected to the output terminals of the charger has an Ampere-hour rating
of at least four times the rated capacity in amperes of the charger.
(b). The ripple is measured at the terminals of the battery.
(c). Check capacitors C1 and C2 as follows: Switch the VoltOhmmeter to the Rx100 scale and
connect the red lead to the capacitor plus terminal (marked by a red dot or plus sign) and the black lead to
the negative terminal. The meter should initially swing up scale toward zero Ohms then come back as the
capacitor charges. A reading of zero Ohms indicates a shorted capacitor while no initial swing means an
open capacitor. Either an open or shorted capacitor should be replaced.
n. Internal Wiring
1. Check internal wiring for obvious mechanical faults or wear. Follow the schematic
diagram on page 28 and check continuity with an ohmmeter to determine open connections. Check wiring
against ground also, and remove any grounds.
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