HP 712B Operating And Servicing Manual page 21

SYMPTOMS POSSIB LE CAUSE TEST PROCEDURE
If voltmeter reads -150 volts or more,
trouble probably is in BV supply cir-
cuit. Set METER RANGE switch at
0-500V and turn HV CONTROL to
maximum clockwise position. If volt-
meter does not deflect, trouble is in
HV supply circuit, and DC voltages
should be checked against those shown
on the schematic. If voltmeter reads
less than 500 volts, trouble may be in
either regulator circuit.
REMEDIES
Locate defective com-
ponent, and replace.
Instrument oper - Defective fus e, or
ating, but output defective tube (or
voltage deviates associated component)
from desired in regulator circuit,
level: as. detailed below:
High Voltage
fu!E.E1y
Voltage slightly Fuse F2 (+HV) blown
negative
Voltage low Fuse F5 (-300V)
blown
VIO
V9
Vl3
V oltage high VII
V12
V7
V8
-300V Bias
Supply
Voltage slightly
positive V8
V7
Voltage low VII
Voltage high V9
VIO
Check for open fuse.
1. Check for open fuse.
2. Check for burned-out tube.
3. If all tubes are operating, check
defective tube in suspected circuit
by substituting tube known to be
good.
4. Test external components in sus-
pected tube circuit.
1. Check for burned-out tube.
2. If all tubes are operating, check
for defective tube in suspected
circuit by substituting tube known
to be good.
3. Test external components in sus-
pected tube circuit.
4-9
Replace blown fuse.
1. Replace blown fuse.
2. Replace burned-out
tube.
3. Replace any defec-
tive tube.
4. Replace any defec-
tive component.
1 • Replace burned-out
tube.
2. Replace any defec-
tive tube.
3. Replace any defec-
tive component.