HP Car 3490A ADJUSTMENTPROCEDUBES, a. Set34904RANGEto, a. Set3490ARANGEto, 5-64.10VRangeAjdustments, $66. OHMMETERADJUSTMENTS, 5-65.100VRangeAdjustments

SectionV		ADJUSTMENTPROCEDUBES			Model34904
c. Adjust A6R32 (l V HF Adj) for 3490A displayof			a. Set FUNCTION to TEST, RANGE to 7. Short Q
1.00000.			Sigral terminals. Adjust A7R5 for display of - 9700.0
d. Change ac calibrator frequency to 100 Hz and			t 100.0 (Instruments with serial numbers below
			l2l1A00656 may not havethis adjustment.)
adjustA6R27 (1 V LF Adj) for displayof 1.00000.
e. Repeat steps c and d until both readings are			b. Set 3490A FUNCTION to O, RANGE to I k.
correct.			c. Connectresistancedecadeto 3490A Input and O
			Signal terminals. Connect 3490A Guard to Input Low,
5-64.10V RangeAjdustments.			and decadeGuard terminal to Low terminal.
a. Set34904RANGEto 10V.			d. Set	decaderesistanceto I kfl and adjust A7Rl4
			(l k Adj) for display of 1.00000 (r decaderesisrance
b. Set ac calibratoroutput to 10.00000V at 100Hz.			error).
c. Adjust A6R28 (10 V LF Adj) for display of			e. Set 349OARANGE to 100 k.
10.0000.			f. Set decaderesistanceto 100 kQ and adiustA7Rl6
d. Change ac calibrator frequency to	100 kHz and		(100 k Adj) for display of 100.000(t decaderesistance
			error).
adjust A6C27 (10 V HF Adj) for displayof 10.0000.If
maximum limit of adjustment is less than 10.0000,			C. Set3490A RANGE to 10,000k.
remove jumper wire in serieswith A6C28.If		minimum
limit of adjustment is greaterthan 10.0000,jumper wire			h. Set decaderesistanceto 10 M{-2and adiustA7Rl8
probably hasbeenremovedand should be replaced.
			(10,000k Adj) for display of 10000.0 (t decade
e. Repeat steps c and d until both readings are			resistanceerror).
correct.			568. If an accurateresistance
					decadeis not available,
5-65.100V RangeAdjustments.			adjustmentof the ohms convertermay be made using
			resistors within		l0 % of Ihe full-range value of I ke,
a. Set3490ARANGEto 100V.			100 kf,} or l0 MO, whose resistancesare known to
			within a closetolerance"Table
					5-10showsthe resistance
b. Set ac calibratoroutput to 100.0000V at 100 Hz.			valuesand the tolerancesrequiredfor valid adjustment.
			The proper adjustment should be made so that the
A6R3 (100 V LF Adj) for display of			3490A display reads the known value of the resistor.
			Perfcirmstep a of Paragraph
,o;.o$j"rt		tL			5-67 before making a_djust-
			mentsin Table5-10.
d. Change ac calibrator frequency to	100 kHz and		5.69SAMPLE/HO.LDADJUSTMENTS.
adjust A6C6 (100 V HP Adj) for displayof 100.000.If			5-70. Adjustment of the dc circuits, Paragraphs5-53
maximum limit of adjustment is less than		100.000,
remove jumper wire in serieswith A6C4. If		minimum	through 560,		must be completedbefore beginningthe
limit of adjustmentis greaterthan 100.000,jumper wire			Sample/Hold adjustments.The following adjustments
probablyhasbeenremovedand shouldbe replaced.			must be performedin the order given.Figure5-10shows
			the location of the Sample/Holdadjustments.They are
e. Repeat steps c and d until both	readings are		alsoshown on the top guard cover.
correct.

$66. OHMMETERADJUSTMENTS.

567.Adjustment of the dc circuits, Paragraphs5-53 through 5{0, must be completedbefore beginningthis procedure.A resistancedecadewith a correctionfactor chart (GR 1433-Z) is requiredfor the following proce- dure. If a suitableresistancedecadeis not availablerefer. to Paragraph548. The enor indicatedby the correction factor chart should be taken into accountwhen adiust- ins the ohmsconverter.For example,if the resistanöeof the decadeis high at I kQ, the 3490A displayshouldbe adiustedto 1.00000plus the resistancedecadeenor.

5-71.0ffsetGainAdjustment.

5-72. A dc digital voltmeter having a resolution of l0pV is required for this procedure,which adjuststhe gain of the Offset Amplifier.

Table5-10. OhmmeterAdjustment.

3490A	Resistance			3490A
Range	Value	Tolerance		Adlustment
1 k o	900o to 1 . 1ko	L O.OO2'yo		A 7 R 1 4
100ko	9 0 k a t o 1 1 0 k a	t	O.OO25o/o	A7R16
0,000 ks,	gMA to 11 MO	!	O . O 1 o Ä	A7R18

_i-16