HP Car 3490A manual P U T Tpc, High, TPC A13CR6, G H Low

Remov€ 413U3. Set FIA- TIO sitch to EXT REF l0V. Disconnect dc atan- dard from INPUT and @6- net to EXT REF t6m.

Monitor voltage 4 Al3 t6t point C whils applying EXT REF bltäges below:

EXT REF TPC '13.6

+ 20 V + to + 14.3 V - 2 0 V - 1 3 . 6t o - 1 4 . 3 V

Refer to G6eäl Trouble- s*rooting Tree, Fig.7.4, min 34904 man@l-

Chrck Inpur Prottrtion C i r c u i t A l 3 C R l - 4 , A13Fl1-3. Aft* rep6ir, go to nexl step.

Replace A13U3 in $cker, Disconned dc sbndard from EXT REF and con- nEt to INPUT terminals. Apply - 10.0000 V. Select TEST 4. Short EXT REF tfrmiEls. With RATIO set to EXT REF 10 V, display should be 00.0000 t.

Perform Ratio Adjust- ren$, Parag.aph 5-79.

Disonnect front penel 6- ble W8 fJom Ratio Asem- bly 413. Ground pin 2 of l E @nnector on A'13Re.- mve 413U2. Connect dc sbndard to A13TPC and monitor voltage at @thode ol Al3CR6 while applying to v:

TPC A13CR6

+ 1 0 V + l 2 . 9 t o + 1 4 . 3 V

- 10 V - 12.9 to -	'14.3
	V

Wirh €ble W8 dis@nnected, pin 2 of c grourded, and U2 removed, set FUNCTIO

FANGE to 1o V. Apply any INPUT vol polaritv lhown b€low, and apply t 10!

YES c'heckinglogic lewls assh@n: (Note 2,

I N P U T TPC			TPD u 5 { 1 2 1
+	f t	0 v	LOW	H I G H
	+ 1 0v		LOW	LOW
	- 1	0v	H I G H	LOW
+	- 1 0 v		HIGH	H I G H

Check A13CR6,7 and re- place if deffttiw- lf diodes a.e good, replace Al3U1

with new Frt. After re- parr, go to next step.