HP 181A manual Power Supply Check, Troubleshooting the Counter

Chapter 2 Service

Troubleshooting the Counter

		Troubleshooting the Counter
		Power Supply Check
		HAZARDOUS VOLTAGES ARE ON THE POWER SUPPLY
WARNING
		ASSEMBLY. ONLY SERVICE TRAINED AND QUALIFIED
		PERSONNEL SHOULD PERFORM THE FOLLOWING
		PROCEDURE.
	1 Remove the power cord from the back of the instrument to
		disconnect the Counter from the power source.
	2 Remove the cover as described in Chapter 3.
NOTE		A4 AC Power Supply Assembly is fused for safety reasons. It is assumed
		that if the fuses are blown, then damage has occurred to the power supply
		which will make it unreliable. Do not attempt to repair the power supply.
	3 Connect the Counter to the power source.
		The fan should begin to operate as soon as power is supplied. If the fan
		does not operate, replace A4 AC Power Supply Assembly.
		Refer to Chapter 3, “Replacing Assemblies,” in this service guide if you
		need to remove or replace an assembly.
		After replacing the power supply assembly, perform the appropriate
		calibration procedures in this chapter.
	4 Connect the negative lead of a voltmeter to the chassis and verify
		that the voltages in Table 2-4 match the voltages measured on
		connector J18 of A1 Motherboard Assembly. See Figure 2-9 for
		illustration of J18 viewing from the bottom of the Counter.
CAUTION		BE CAREFUL to NOT short the positive-side lead of the voltmeter to the
		chassis when probing at the testpoints shown in Figure 2-9.

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Assembly-Level Service Guide 2-45