HP 5340A Service Manual

Model 5340A
Maintenance and Service
5 - 39. Power Supply Troubleshooting
a.
Determine which power supplies are regulating
at an incorrect voltage by measuring the
output voltage.
If any supply
is at or near zero volts, the supply could be current limiting. Disconnect the
output leads for that supply
at the A30 power supply motherboard.
Again measure the voltage. If the output
is still bad, the failure exists in the power
supply circuit.
Use the typical voltage charts shown to isolate the defective components.
If the output obtained in step
3 is now good, there could be a short circuit in the instru -
ment, or the supply could be current - limiting improperly. Substitute a resistive load for
the supply under test
as listed on the next page.
If the output is still good, an excessive load exists somewhere in the instrument.
Connect
an ohmmeter between ground and on the feeder line in question (which
is still discon -
nected from its power supply).
Start removing the plug
- in PC boards until a significant
change is observed on the ohmmeter. Then isolate the execessive load. Check also for
shorted wires.
If the output obtained in step
4 is bad, the power supply is not able to provide the neces -
sary current.
Use the typical voltage charts to isolate to the defective component.
Look
especially for the same voltage on any two leads of a transistor, indicating a shorted
transistor.
b.
c.
d.
e.
f.
5 - 20

HP 5340A Specifications

General

Brand	HP
Model	5340A
Category	Cash Counter
Language	English