PRINTED CIRCUIT BOARD AND PARTS LOCATION
FIGURE 1
WARNINGCAUTION
After replacing high-voltage parts such as the fan, powerSimilar wire colors and connectors with the same number
cord, rear panel convenience receptacle, or printed wir-of pins are used in different circuits; make sure proper
ing assemblies SHR-11, SHR-12, or SHR-14 (or theirreconnections are made. Push-on connectors must be
components), make certain that a dielectric voltageremoved by pulling straight out. The side of a small screw-
breakdown test is performed before connecting the unitdriver blade inserted between the free and fixed connector
to a power supply. With the unit disconnected from the accan sometimes be helpful in separating the connector.
source, turn the unit on and measure the resistanceDo not apply side force when removing or reconnecting
between the ground contact of the power plug and eachterminals, or damage may result. Reference to the service
of the other two prongs. This resistance should measureillustrations will be helpful in case of difficulty.
infinite. Then measure the resistance between the plug
ground and exposed metal parts of the chassis, screws,
connectors, fan grille, etc. This resistance should be zero
ohms. If any measurements are recorded outside theGENERAL SERVICE PROCEDURE
To isolate a problem area, a general procedure is as follows. If
specified limits, a shock hazard exists. The unit must bethe Powermixer is completely dead, check the ac power source,
repaired and rechecked before it is returned to operation.line cord, and fuses (external and internal). If the unit turns on
IMPORTANT: When removing any printed wiring board, be surebut operation is abnormal, check the chassis power supply
the wires and connectors detached from the board are identifiedoutput (-56 Vdc between test point SHR-11-AB and ground,
for proper reconnection. This may be done by affixing a pieceand +56 Vdc between test point SHR-11-AA and ground; -15
of masking tape marked with the reference designation Vdc across C1421, +15 Vdc across C1420, and +24 Vdc
(connectors) or terminal letter or color (wires).between P1404-A and ground). If the measured dc voltages are
NOTE: Any cable ties that were loosened or removed must becorrect, perform additional AC and DC Voltage Measurements
tightened or replaced after servicing.as described below to isolate the problem.
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ACEC
