HP 1317A Operating And Service Manual page 65

ModelI317A
8-43. Voltage Too Low. Adjust the +250V supply
(AIIRI2) while measuring the output of the supply.
If proper adjustment cannot be made, check the
resistor divider network, AIIRII, AIIRI2, and
AIIRI3 for proper values. Check for low input line
voltage.
8-44. TROUBLESHOOTING THE HIGH VOLTAGE
POWER SUPPL V.
WARNING
I
Contact with the high voltage power
supply voltage can result in injury or
death.
8-45. Malfunction of the high voltage power supply
will usually result in loss of beam spot or unstable
intensity. Troubleshooting may be accomplished by
resistance checks of the high voltage oscillator, high
voltage transformer, and regulator circuits. In the
event of complete failure, check fuse AI3Fl. If fuse
is all right, check -15V supply. Failure of the -15V
supply will tum off high voltage oscillator A13Q4.
In the event of octupler failure, replace the assembly.
8-46. TROUBLESHOOTING X-, V-, Z-AXIS AMPLI-
FIERS.
8-47. The X-axis and Y-axis amplifiers are identical.
When trouble develops in either the X-axis circuit or
Y-axis circuit (not both), the quickest way to isolate
the problem to a board assembly is by substitution.
Interchange board assembly Al with board assem-
bly A3. If trouble still exists, interchange board as-
sembly A2 with board assembly, A4. This procedure
should isolate the problem to a particular board
assembly.
Service
8-48. Trouble in the X-axis and Y-axis amplifier cir-
cuits will usually result in an unbalanced condition.
The spot will usually shift from the center of the CRT
and, in some instances, may leave the viewing area
completely. Troubleshooting the differential stages
may be done by clamping the stages within a differ-
ential amplifier together. The following steps de-
scribe this method.
@Effi
When clamping the bases of the differen-
tial amplifier stages together do not
allow the jumper wire to contact the
chassis or other components. Damage to
the equipment may result.
a. Use short jumper wire with insulated mini-
ature clip at each end.
b. Turn instrument off while making con-
nection.
c. For example, connect jumper between bases
of AIQII and AIQI2 (see schematic 2). Connection
between bases may be made at base side of AIR77
and base side of AIRSl.
d. With jumper in place, turn instrument on. If
beam spot returns to center of CRT, AIQII and
AIQI2, along with output amplifier assembly, A2,
are functioning properly. The trouble is back toward
input circuit.
e. By selecting differential stages, either toward
input or toward output, faulty stage can be isolated.
Using voltage and resistance measurements, faulty
component should be easily identified.
8-3