HP Car 3490A 4-134Logic.Test,No.l, +I32 . SELF . TESTFUNCTION

SectionIV					Model3490A
		Table4-2. Polarityin Ratio Measurements.
				Measurement Run-down
External	I nput	Ratio	Displayed
Reference	Signal	Polarity	Polarity	Reference	Amplifier
I nput		Signal		Required	Output Used
+		H I G H	+		Invert. Amp.
+	+	LOW			Ext. Ref. Amp.
		LOW		+	Ext. Ref. Amp.
		H I G H			Invert.Amp.
		H I G H	none		Invert. Amp.
		LOW	none		Ext. Ref. Amp.

volts is used as a reference for the + 30 V, + 5 V and

-17V regulatorsThe. -30Vregulatoruses- 17V asa referenceUl02. in the - 17 V supplyis operatedoff raw supply thru CR123 until the -30Vsupply comesup after turn-on.It is then operatedoff - 30 V thru CRl22. The - 5 V supply is zener regulatedfrom the - l7V supply. All suppliesexcept the - 5 V supply are voltage regulatedand currentlimited for protection.The output of eachsupply is limited by a zenerdiode to protect the circuitsit supplies.

Table4-3. AnalogTests.

	Run-Up		Run-Down
T€sl	DC Amp.	DC Amp.	DC Amp.	DC Amp.
No.	Input	Gain	Input	Gain
2	Ground	x 1	+ Ref/- Ref	x 1
J	+ Ref/- Ref	x l	- Ref/+ Ref	x l
4	+ Ref	x l	Input x 1	x l
5	Ground	x 1 0 O	+ Ref/- Ref	x l
6	Input x 0.01	x 1 0 0	+ Ref	x 1
7	o Ref	x 1 0	+ Ref	x 1

+I32 . SELF . TESTFUNCTION .		4-134Logic.Test,No.l.
+133.	Seven tests, which may be selectedby front	4-135. A seriesof ten readings,shown below, provide
panel switch settings or by optional remote control,		visible indication as to whether the display and certain
provide internal checkson the operationof many of the		logic circuits are operating correctly. Note that the
3490A	circuits. Test No. I checksapproximately70%	instrument autorangesone stepfor eachreading,uprang-
of the	logic circuits, and the other six check analog	ing through all ranges, then downranging through all
circuits as explainedin the following paragraphsand in		ranges.Note also that the numerical display changesfor
Table4-3.		each range. In logic test, two factors determine the

FULL- WAVE R E C TFI I E R cRil9 - t20

R E C TIF I E R

REF

REGULATOR

Figure4-17. PowerSupply Block Diagram.

+ l b ,