HP 181A manual After Service Considerations, Product Safety Checks, Product Performance Checks

Chapter 2 Service

Pre-Troubleshooting Information

	After Service Considerations
	Product Safety Checks
	The following safety checks must be performed after any troubleshooting
	and repair procedures have been completed to ensure the safe operation of
	the instrument.
	RESISTANCE CHECKS DESCRIBED IN THE FOLLOWING TEXT
WARNING
	REQUIRE THAT THE POWER CORD BE CONNECTED TO THE
	INSTRUMENT AND THAT AC POWER BE DISCONNECTED.
	BE SURE THAT THE POWER CORD IS NOT CONNECTED TO
	POWER BEFORE PERFORMING ANY SAFETY CHECKS.

1VISUAL INSPECTION. Visually inspect the interior of the instrument for any signs of abnormal internally generated heat, such as discolored printed circuit boards or components, damaged insulation, or evidence of arcing. Determine and remedy the cause of any such condition.

2GROUND CONTINUITY TEST. Plug the power cord into the rear-panel power receptacle. (DO NOT connect the instrument to ac power at this time.) Using a suitable ohmmeter, check resistance from the instrument’s

metallic connection (such as the rear panel or BNC ground collar) to the ground pin on the power cord plug. The reading must be less that 1Ω. Flex the power cord while making this measurement to determine whether intermittent discontinuities exist.

3Check any indicated front- or rear-panel ground terminals marked, using the above procedure.

4INSULATION RESISTANCE TEST. Tie the line and neutral pins of the power cord plug together. Measure the resistance from the instrument

enclosure (chassis) to the line and neutral pins of the power cord plug. The minimum acceptable resistance is 2 MΩ. Replace any component which results in a failure.

Product Performance Checks

After replacement of any assembly or module, perform the operational verification test in Chapter 1, “Performance Tests,” of this guide.

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Assembly-Level Service Guide 2-39