PS S5.3 5230
001
Version no T-code
F-code Section C-code
SCR Component Checks
182
Service Manual 1997-04-15
6. Rectifiers
(3REC, 4REC, Diode Blocks)
When checking diodes, disconnect battery and discharge
capacitor 1C. When replacing rectifiers, refer to TABLE 5. For
3REC and 4REC, disconnect one lead or flexible connection.
3REC and 4REC are diodes with about 7 to 12 ohms in the
conducting direction (anode to cathode) measure on the
Rx100 scale, and 10,000 ohms or higher, in the non-
conducting direction (cathode to anode) measured on the
Rx10,000 scale.
7. Thermal Protector (TP)
Remove both the GRAY and BLACK wires from the “Z” plug
that connects to the control card. Read the resistance
between these two wires with the VOM set on the Rx100
scale. VOM should read 100 to 200 ohms if the 1REC
heatsink is at room temperature (75°F or 25°C). Set the VOM
to the highest ohm scale and read from each wire end to the
1REC heatsink. Reading should be infinity.
NOTE!
If you do not have a test light to check the
SCR’s as described above, they may be
checked for shorts and opens by use of the
VOM.
NOTE!
Measure resistance from anode to cathode
(Rx100 scale. If SCR is shorted (zero ohms),
it must be replaced.
NOTE!
Measure resistance from the gate terminal to
the cathode and then from the cathode to the
gate terminal (Rx100 scale). If resistance
reads either zero ohms (short) or infinity
ohms (open), replace the SCR. When
resembling SCR’s, refer to TABLE 5.
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