HP Car 3490A manual Procedures, Adjustment, $ 51 .ADJUSTMENTPROCEOURES, Powebsupplyadjustment

SectionV	PROCEDURES	Model3490A
	ADJUSTMENT

$ 51 .ADJUSTMENTPROCEOURES .

5-52. Complete adjustment proceduresfor the Model

3490A Multimeter, including options, are containedin the following paragraphs.These proceduresshould be performed only after it has been determined from the PerformanceTeststhat the 3490A is out of adjustment. The adjustmentsin Paragaphs5-53 through 5-60 must be performed in the order given,and before the ac, ohm, sample/hold and ratio adjustments.If any adjustment cannot be made correctly, refer to the Troubleshooting Proceduresin Section VII. Location of adjustmentsin the standardinstrument is shownin Figure5-9,Sample/ Hold adjustmentsin Figure 5-10,and Ratio adjustments in Figure 5-l l. All adjustmentsare shown on the top guardcover.Turn the 3490A on and allow it to warm up for at least 4 hours with the coverson before performing the adjustment procedures. The top cover must be removedto gainaccessto the adjustments,which should be madewith the guard(inner) coveron.

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The inner cover is qt Guard potential. Use caution to prevent shock when high voltages are connectedto the Input.

5.53.POWEBSUPPLYADJUSTMENT.

5-54. A dc digital voltmeter with 4digit resolutionand an oscilloscopearerequiredfor this adjustment.

a.Connect digital voltmeter and oscilloscopebe- tween the + 17 V testpoint on AlAl and the input Low terminal.

c.Set the sample rate on HOLD and measurethe ripple present with the oscilloscope.If the voltages specifiedin Table 5-9 cannot be met, refer to Section VII, TroubleshootingandCircuit Diagrams.

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Figure5-9. Locationof Adjustments,Standard3490A.

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