HP 5501B Operating And Service Manual page 90

5. Turn the power off and disconnect the high voltage connector. Carefully connect a
high voltage probe, (you will need to make a jumper to extend the probe into the
high voltage connector).
6. Turn power back on and perform an open circuit voltage test. Before performing the
open circuit voltage test, wait until the laser is in optical mode. This is indicated
when LED A3DS2 is on. If A3DS2 is off, check A3 logic circuitry. A3DS2 should turn
off approximately 100 seconds after reapplying power. The voltage should be 10kV
to 12kV. If not, replace the high voltage power supply. If the laser still doesn't work
then replace the laser assembly.
AFTER TESTING, THE POWER SUPPLY MAY TAKE UP TO 3
MINUTES
THEREFORE, SHORT ANODE TO GROUND IMMEDIATELY.
b. Laser light is emitted but flashes or causes a REF Error.
1. Turn power off and disconnect A1J4. Insert a 1K, 1%, 0.5 Watt resistor (Rt)
2. Connect an oscilloscope across Rt.
3. Turn on power and allow the laser to warm up.
4. Observe DC test voltage. It should be between 3 and 4 Volts. If not, perform the
5. Set the oscilloscope to view the AC component and calculate the percent ripple.
6. Disconnect external ±15 Volt power supplies from laser head.
7. Remove resistor R
8-30
FOR THE OPEN-CIRCUIT
between the J4 (pin 1) connector. [Leave J4 (Pin 2) disconnected].
current adjustment procedure in
There should be less than 3% ripple in the test voltage. If not, replace the HV
power supply. If the ballast resistor is bad, the test voltage might be an aperiodic
intermittent voltage. If this is the case, replace laser tube assembly.
and replace connector to A1J4.
t
If a power supply problem seems intermittent, gently
tapping the HVPS with a screwdriver will induce the problem
for test purposes.
VOLTAGE
Section 5-17 of this manual.
NOTE
HP5501B
Service
TO DECAY.