A1 Connector Board Troubleshooting; Rear Panel Led Operational Check - HP 5501B Operating And Service Manual

8-81. If either the +15 Vdc or -15 Vdc 1.5 Amp fuse opens, the difference in potential that results
(across DS1 or DS2) will forward bias the associated LED indicator, turning that fuse indicator on.
8-82. System operating power is distributed to the laser head and other transducer units via the
connector board. Safety switch A1S1 opens when the laser head covers are removed. This
disconnects -15 Vdc from the high voltage power supply. As a result, this power supply
becomes inoperative. The +15 Vdc input is applied to regulator A3U7 on the A3
Reference/Control Board. This regulator provides +5 Volts for use within the laser head. The +5
Volts is used to drive laser head's logic circuitry, READY LED (A1DS8), and as a reference for the
high voltage power supply switch.

8-83. A1 CONNECTOR BOARD TROUBLESHOOTING

HIGH VOLTAGE IS PRESENT ON A1J4 IF THE LASER IS ON AND
THE TUBE CONNECTOR IS NOT CONNECTED TO A1J4.
8-84. Use the schematic diagram Figure 8-23, an ohmmeter, and a voltmeter to troubleshoot A1.
Check to see if A1F1 is blown. Check for proper transmission of power supply voltages. Check
for proper diode action across A1CR1 and A1CR2. Check A1C1 through A1C5 for shorts. Check
switches A1S1 and A2S2. Check A1R3 and A1R4.

8-85. Rear Panel LED Operational Check

MAINTENANCE
POWER
PROTECTIVE COVERS REMOVED. SUCH MAINTENANCE SHOULD
BE PERFORMED ONLY BY SERVICE- TRAINED PERSONNEL WHO
ARE AWARE OF THE HAZARDS INVOLVED (FOR EXAMPLE, FIRE
AND ELECTRIC SHOCK). WHERE MAINTENANCE CAN BE
PERFORMED WITHOUT POWER APPLIED, THE POWER TO THE
EQUIPMENT SHOULD BE REMOVED.
FROM 1.2 KILOVOLTS TO 12 KILOVOLTS DC IS PRESENT ON THE
ANODE OF THE LASER TUBE IN THE HP5501B. EXERCISE
EXTREME CAUTION WHEN WORKING INSIDE THE INSTRUMENT.
THE HIGH VOLTAGE COULD CAUSE SERIOUS PERSONAL INJURY
IF CONTACTED.
PERFORMED BY SERVICE-TRAINED PERSONNEL ONLY.
8-86. The following procedure can be used as an operational check of the rear panel LED's. Perform
only if a problem is suspected.
a. Remove HP5501B instrument covers as described in paragraph 8-55.
b. Leave TEST-NORM switch (A1S2) set to NORM.
c. Apply power to laser head as per Figure 4-1. (Use HP 6255A Dual DC Power Supply or
its equivalent.)
DESCRIBED
SUPPLIED TO THE
THE INSTRUMENT
HEREIN IS PERFORMED
EQUIPMENT AND
SERVICE
HP5501B
WITH
WITH THE
SHOULD BE
Service
8-27