Model3490AAOJUSTMENTPROCEDURESSectionV

d.Check other power supply voltagesby connecting digital voltmeter and oscilloscopeto test pointslistedin

Table 5-9. If any voltageis not correct,refer to Section

vu.

 

 

 

 

 

Voltages.

 

Table5-9. PowerSUPPIY

 

 

A 1 A 1

 

 

 

 

Ripple*

TestPoint

 

Voltage

+ 17\l

+ 16 . 99 to + 17 . 01V

< 50 mV p-p

+

5 V

+

4.995to + 5.075V

< 60 mV p-p

+ 3 0 V

+ 30.10

to + 30.90V

( 25 mV p-p

-

1 7 V

- 16 . 9

to - 17 . 1 V

< 50 mV p-p

-

5 V

-

5.00

to -

5.85 V

( 6 0 m V p p

-

3 0 v

- 30 . 10 to -

30 . 90V

( 2 5 m V p {

*All ripple measurementsare with the SampleRate on HOLD .

5.55.DCZEROADJUSTMENTS.

5-56. A dc standard(-hp- 7a0B) and a dc voltmeter able to resolvel0 pV are required for theseadjustments.

a.Connect dc voltmeter betweenAlAl test point A and input Low terminal.

b.S€t 3490A SAMPLE RATE control fully counter- clockwise to HOLD position.

c.Adjust AlAlR2l0 (lntZero) for voltmeter read- ing of 0 r 150gV. Disconnectvoltmeter.

d.Set FUNCTION to DC. RANGE to l0 V. SAM- PLE RATE to FAST.

e.Connect dc standardto 3490A input and adjust standardoutput to + 0.00100V.

f.Adjust AlAlR225 (Zero DetecI kvel) for maxi- mum readingon 3490A display.Note reading.

C.Reversepolarity of input and adjust AlAlR228 (Tumover) for reading noted in step f. Continue reversinginput polarity and adjustingAlAlR228 until positive and negativereadingsare equal.

h.Apply + 0.00100V input to 3490A. Adjust AlAlR225 (Zero Detect kvel) for 3490A display of

+00.0010.

$57. REFERENCEADJUSTMENTS.5-58.A dc standard(hp- 7a0B)is requiredfor these

adjustments.

Guqrd Terminal should be connectedto Low or damageto the instrument may result.

a. Set 3490A FUNCTION to DC. RANGE to t0 V.

b.Connectdc standardto 3490Ainput andadjust standardoutputto - 10.0000v.c.AdjustAlAlR3ll (+Ref) for 3490Adisplayof

-10.0000.

d.Set 3490AFUNCTIONto TEST,RANGEto 3. AdjustAlA1R3l7 (- REF)sothatpositiveandnegative display readingsare equal within I count. Last digit mustbe between2 and9 (0.9999x)If. not,repeatsteps a throughd. Dsconnectdcstandard.

5.59.DCAMPLIFIERADJUSTMENTS.560.A dc standard(hp- 7a0B)is requiredfor these adjustments.

a.Set 349OAFUNCTIONto DC, RANGEto .l V. Shortinput terminalswith a copperbar or heavysolid copperwire.

b.Adjust AlR429, accessiblethroughhole in rear panel,for 3490Adisplayof 0 r .000002.c.Set3490ARANGEto I V.

d.Removeshort from input terminalsandconnect dcstandardAdjust.standardoutputto - 1.000000V.

e.Adjust A2Rl5 (l V Adj) for 3490A displayof

-1.00000.

f.Set 3490A RANGE to 100V, and adjust dc standardoutputto - 100.000V.g.AdjustA2R3 (100V Adj) for 3490A displayof-100.000.Reducedc standardoutput and disconnect.

h.Set 3490A FUNCTIONto TEST,RANGEto 6. Shortinput terminalsandnote amountandpolarity of oTfsetreading.

i.Removeshortandapply- 10.0000V input.Adjust A2Rl6 (0.1V Adj) for displayof - 1000.00,minus (algebraicallysubtracting)the offsetnotedin steph.

$6I. ACCONVERTERADJUSTMENTS.

5-62.Adjustmentof the dc circuits,Paragraphs5-53 through5-60,must be completedbeforebeginningthis procedure.An ac calibrator(-hp- 745A)with a correction factor chart is requiredfor theseadjustments. Guardcoversmustbein placefor thisprocedure.

5-63.I V RangeAdjustments.a.Set3490AFTINCTIONto AC.RANGEto I V.

b.Connectaccalibratorto 3490Ainput.Setcalibra- tor outputto I .000000V at 100kHz (usingcorrection factorchartasnecessary).

s-l5