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5-61 ADJUSTMENT AND CALIBRATION
5 -6 2 METER ZERO
5-63 Proceed as follows to mechanically zero
meter:
a.
Tum 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 indentation near top of round
black plastic disc located directly below meter
face.
c.
Rotate plastic disc clockwise (cw) until
meter reads zero, then rotate ccw slightly in
order to free adjustment screw from meter suspen-
sion.
If pointer moves, repeat steps b and c.
5-64 METER ACCURACY ADJUSTMENT
5.-65 To adjust the electrical meter accuracy,
proceed as follows:
a.
Connect the 100: 1 attenuator and the dif-
ferential voltmeter as illustrated in Figure 5-2.
b.
Adjust the VOLTAGE thumbwheels until
the differential voltmeter indicates 30. 00 volts.
c.
Adjust R67 until the front panel volt-
meter indicates exactly 3000 volts.
5-66 OUTPUT VOLTAGE (PROGRAMMING CURRENT)
ADJUSTMENT
5-67 To adjust the output voltage, proceed as
follows:
a.
Connect the 100: 1 attenuator and the
differential voltmeter as illustrated in Figure 5-2.
b.
Turn the VOLTAGE thumbwheel switches
to
av.
c.
Remove R51 and R52 and connect the
decade box (set to approximately 200 ohms) to the
standoff terminal in place of R52.
d.
Adjust the decade box until the differen-
tial voltmeter indicates 30. 00Vdc.
5-17
e.
Note the setting of the decade box and
connect the next highest value resistor in the R52
position on the circuit board. This resistor should
be a 1%, l/4W Metal Film type with a temperature
coefficient not greater than 100 ppm per degree
centigrade.
f.
Readjust the decade box until the differ-
ential voltmeter again reads 30. 00Vdc.
g.
Note the setting of the decade box and
connect an equal value resistor to the standoff
terminals for R51.
This resistor should be 5%,
l/2W carbon composition:
5-68 OUTPUT CURRENT LIMIT ADJUSTMENT
5-69 To adjust the limiting level of the output
current, proceed as follows:
a.
Attach the multimeter or a milliammeter
to the output terminals of the supply.
Set the
meter for approximately 10
mA.
The internal re-
sistance of the meter is low enough to overload
the supply so that the output will current limit.
b.
Set the VOLTAGE thumbwheel switches
to 300 volts.
c.
Adjust current limit control R70 until the
meter indicates 8. 2 mA.
5-70 OVERVOLTAGE PROTECTION
5-71 To adjust the overvoltage protection feature
so that the output voltage will not exceed 3000V
under any circumstances, proceed as follows:
a.
Connect a SOOK, 18W load resistor to
the output of the supply and connect a Variac to
the input.
b.
Turn on the power supply and adjust the
Variac for
l
27Vac.
c.
Set the output VOLTAGE controls for
3000Vdc.
d.
Turn overvoltage potentiometer R71
clockwise until neon light VR3 is on; then turn
R71 slowly counterclockwise until VR3 extinguish-
es.
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