TM 11-6625-2965-l4&P

Table 5-7. Checks and Adjustments After Replacement of Semiconductor Devices (Continued)

REFERENCE

 

FUNCTION

 

CHECK

ADJUST

 

 

 

 

 

 

 

Q10, CR16

 

 

 

Current

limit adjustment.

R81

(CR21)

 

 

 

 

 

 

 

 

 

 

 

 

 

CR22 thru

Rectifier

diodes

 

Voltage

across appropriate

 

CR29

 

 

 

filter capacitor.

 

 

 

 

 

 

 

VR1

Positive

reference

voltage

+6.2V line and load regu-

R46, VR1

 

 

 

 

lation.

 

 

 

 

 

 

 

 

VR2

Negative

reference

voltage

-6.2V line and load regu-

R46, VR2

 

 

 

 

lation.

 

 

 

 

 

 

 

 

 

5-60 ADJUSTMENT AND CALIBRATION

5-61 Adjustment and calibration may be required after performance testing, troubleshooting, or repair and replacement. Perform only those adjustments that affect the operation of the faulty circuit and no others.

5-62 METER ZERO

5-63 Proceed as follows to zero meter:

a.Turn off instrument (after it has reached normal operating temperature) and allow 30 sec- onds for all capacitors to discharge.

b.Insert sharp pointed object (pen Point or

awl)

into

the small hole at top of round black plas-

tic disc

located directly below meter face.

 

 

c .

Rotate

plastic

disc

clockwise (C W)

until

meter

reads zero,

then

rotate

ccw slightly in

order

to free adjustment screw from meter suspension, If pointer moves, repeat Steps b and c.

5-64 AMMETER TRACKING

5-65 To calibrate the ammeter, proceed as fol- lows:

a. Connect test setup as shown on Figure

5-4.

b. Set RANGE switch to low voltage mode

 

and

METER switch to lowest current range.

 

c . Turn on supply and adjust VOLTAGE con-

trols so that differential voltmeter indicates ex-

actly

40Vdc.

 

d. Front panel meter should read 0.3 Amp

for Model

6204B and 6205B supplies, or 0.1 Amp

for Model

6206B supply. If it does not, adjust R72.

5-66 CONSTANT VOLTAGE PROGRAMMING CURRENT

5-67 Programming Accuracy. To calibrate the programming current, proceed as follows:

a.Connect an 8K, 0.1% resistor (18K re- sistor for Model 6206B supplies) between termi-

nals -S and A6 on rear barrier strip.

b.Disconnect jumper between A7 and A8 (leaving A6 and A7 jumpered).

c.Connect decade resistance box in place

of R13.

d.Connect differential voltmeter between

+S and -S terminals on rear barrier strip.

e . Set RANGE switch to high voltage mode, METER switch to high voltage range, and turn on supply.

f.Adjust decade resistance box so that differential voltmeter reads 40 ± 0.4Vdc for Models 6204B and 6205B or 60 ± 0.6Vdc for Model 6206B supplies,

g . Replace decade resistance with resistor of appropriate value in R13 position.

5-68 Zero Output Voltage. To calibrate the zero Volt programming accuracy, proceed as follows:

a.Connect differential 1 voltmeter between +S and -S terminals.

b.Short out voltage controls by connecting jumper between terminals A6 and -S.

c. Turn on supply and observe reading on

differential voltmeter.

d.If it is more positive than O Volts, shunt

resistor R6 with a decade resistance box.

e.Adjust decade resistance until differen- tial voltmeter reads zero, then shunt R6 with re-

sistance value equal to that of the decade resist- a n t e .

f.If reading of Step c was more negative than 0 Volts, shunt resistor R8 with the decade resistance box.

g.Adjust decade resistance until differen- tial voltmeter reads zero then shunt R8 with a re- sistance value equal to that of the decade box.

5-13