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WARNING
1
2
NOTE
3
4
Chapter 2 Service
Troubleshooting the Instrument
Troubleshooting the Instrument
Power Supply Check
HAZARDOUS VOLTAGES ARE PRESENT ON THE POWER
SUPPLY ASSEMBLY. ONLY TRAINED AND QUALIFIED
SERVICE PERSONNEL SHOULD PERFORM THE FOLLOWING
PROCEDURE.
Remove the power cord from the back of the instrument.
Remove the cover as described in Chapter 3.
The DC Power Supply Assembly is fused for safety reasons. It must be
assumed that, if the fuses are blown, the power supply has probably
suffered damage and has therefore become unreliable. If the power supply
fails, it must be replaced, even if the fuse in the power supply appears to
be all that has failed.
Connect the instrument to the power source.
Connect the negative lead of a voltmeter to the chassis and measure each
of the voltages listed in Table 2-3 on Power Supply connectors TB1 and
TB2 (see Figure 2-10).
Neutral
TB1 (AC In)
Line
Approx. location of R23
Figure 2-10. A4 DC Power Supply Test-Point Locations
2-28
Pin 8
TB2 (DC Out)
Pin 1
Assembly Level Service Guide
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Troubleshooting
