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CONTROL CIRCUITRY (continued)
ANY INTERRUPTION of the control circuit will disable K1 and open the AC circuit to the rectifier.
addition to the above lamphead interlock switches, thermal switch TS1, mounted to the rectifier heat
sink, will open and disable K1 if the temperature at the heat sinks exceeds 190° F. (88° C.).
switch will automatically re-set when temperatures fall to safe levels.
POWER CONVERSION PROBLEMS
RECTIFICATION (AC to DC) is performed by bridge diodes CR1 - CR6.
diodes, and CR4, CR5, and CR6 are reverse diodes.
AN OPEN DIODE will cause a pronounced flicker in the light output. Two or more open diodes will
disable bulb ignition.
following DIODE TESTING & REPLACEMENT section.
BANKED CAN CAPACITORS C1A & C1B filter the rectified DC output.
store energy to contribute to the open circuit ignition discharge.
AC circuit breaker.
RELAY K2, in the presence of high DC open circuit voltage, will pull and place Resistor R2 in series with
Capacitors C1 and C2.
to promote bulb ignition. If K2 relay fails, ignition may become erratic, and R2 may remain in circuit.
With R2 in circuit, ripple will increase to a level noticeable in light output, but not necessarily enough
to trip the AC line circuit breaker.
DIODE TESTING & REPLACEMENT
1. Disconnect the diode from its circuit.
junction.
2. A "shorted" diode will show low resistance in both directions.
resistance in both directions. An Ohmmeter test is required.
3. a) Analog VOM: Select R x 1 Ohm scale.
reading should be zero (or nearly so); reversing the meter leads should show very high resis-
tance.
If the diode does not exhibit these characteristics, replace it. NOTE DIODE TYPE: forward
or reverse.
b) Digital VOM:
should be "OL" (overload); reversing the meter leads should display approximately .4 volt. If the
diode does not exhibit these characteristics, replace it. NOTE DIODE TYPE: forward or reverse.
4. Carefully clean the area of the heat sink in which the diode mounts.
(Radio Shack #276-1373 or equivalent) using a wood or plastic spatula or stick.
a d e q u a t e .
5. Install the new diode and tighten securely for maximum mechanical contact and electrical con-
duction. Clean and firmly secure the lead terminal to the buss.
16
A shorted diode will trip the circuit breaker protecting the AC input line. See the
This resistor limits the inrush surge and prolongs the discharge of C1A & C1B
Inspect for discoloration, oxidation, or loose crimp at lead
Select "Diode Test." With meter leads connected in one direction, the reading
HEAT SINK COMPOUND IS HIGHLY CAUSTIC.
Do not apply with fingers; keep away from
eyes.
Carefully follow ALL the instructions
printed on the package.
The two types are not interchangeable.
An "open" diode will have infinite
With meter leads connected in one direction, the
WARNING
CR1, CR2, and CR3 are forward
C1A and C1B capacitors also
A shorted capacitor can trip the
Apply heat sink compound
A thin layer is
In
The TS1
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