Citizen GSX-190 Service Manual download pdf (Page 105)

PN 4237242C

4.5-1

SERVICE AND REPAIR PROCEDURES

AT POWER SUPPLY

4.5 AT POWER SUPPLY

Tools/Supplies Needed

B #2 Phillips-head screwdriver

B Voltmeter

Removal

1. Turn OFF the instrument’s power.

2. Disconnect the ac power cable from the rear of the power supply (Figure 4.3-1).

3. Remove the top cover as directed under Heading 4.3.

4. Remove electrical connections to the power supply:

r P1 connects to the floppy disk drive power connector.

r P2 connects to a cable from the lower chassis terminating at the AC Power/Vacuum

Relay card.

r P4 and P5 connect to the AT motherboard connectors P8 and P9.

5. At the rear of the instrument, remove the two #2 Phillips-head screws holding the power

supply to the chassis (Figure 4.3-1).

6. Remove the power supply from the chassis.

Installation

1. Ensure that the input voltage (115 V or 230 V) is set correctly on the new power supply.

Use the slide switch just above the ac line connector to set the input voltage.

2. Install the new power supply. The power supply "hooks" into the chassis and must be

slid from front to back to properly engage, before fastening screws.

3. At the rear of the instrument, replace the two #2 Phillips-head screws holding the power

supply to the chassis (Figure 4.3-1).

CAUTION

Risk of electronic damage. If connectors P4 and P5 are attached incorrectly, the motherboard will

be damaged. They can only be installed correctly one way. They are, however, identical and could easily be

switched. To ensure that P4 and P5 are installed correctly, attach them so that the black wires from each

connector are situated together in the middle.

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Citizen GSX-190 Service Manual Page 105