A1 Connector Board Circuit Theory; Power Distribution; A1 Connector Board Troubleshooting; Rear Panel Led Operational Check - Agilent Technologies 5517B Operation And Service Manual

Checkout Procedure to get an indication of the function of the optical tuning subsystem before proceeding
with lower level testing. Use the Reference Receiver Troubleshooting Procedure, paragraph 8-150, to check
signal level if the laser tube assembly and tuning circuits appear to be functioning properly. If the READY
LED does not extinguish, spurious errors may be occurring on the REFerence frequency signal. Various
internal and external noise or interference may be responsible. Check A3 ground connections and Vcc
coupling capacitors. Check that the HP 5517B/C/D covers are fastened securely. Marginal optical signal to
the reference receiver may aggravate noise problems. Check for adequate signal according to Reference
Receiver Troubleshooting, paragraph 8-150. Improper system grounding may also cause noise problems, see
Section II.

8-75. A1 CONNECTOR BOARD CIRCUIT THEORY

8-76. The A1 Connector Board interconnects the main laser cable, laser tube heater, laser power supply, and the A3
Controller/Reference Board. The schematic diagram for A1 is shown in
8-77.
Capacitors A1C1 through A1C3 serve to filter out noise on the ±15 Volt power supply lines. A1C4 filters
current spikes created by the high voltage power supply. Diode A1CR1 provides reverse voltage protection and
A1CR2 protects against electrical transients. Fuses Al Fi and A1 F
failures. A1J4 is the connector for the laser tube heater and cathode. A1 DS5 and Al DS6, +15V POWER ON and -
15V POWER ON LEDs respectively, turn on when the power cable is connected to POWER connector A1J2. A1 DS8
(LASER ON LED) lights when the high voltage supply is powered. AT DS7 (READY LED) lights when the HP
5517B/C/D is ready for use. A1 R12 is used to adjust laser current as per the adjustment procedures in Section V.

8-78. Power Distribution

8-79. When +15 Vdc and -15 Vdc are applied to the laser head, the ±15V POWER ON light-emitting diode indicators
(on the A1 Connector Board) are forward biased and illuminate.
8-80. If either the +15 Vdc or -15 Vdc fuse opens, the associated LED indicator extinguishes.
8-81. System operating power is distributed to the laser head via the connector board. The +15 Vdc input is also
applied to the A3 Reference/Controller Board where it splits into two +15V supplies. One supply (+15VH) is routed
solely to the collector of Darlington transistor A3Q3 which is located in the A3 Power Amplifier section. The other
passes through fuse A3F1 and supplies +15 Volts to the A3 analog circuits and to the +5 Volt regulator A3U7. The
+5 Volts is used to drive the laser head's logic circuitry and READY LED (A1DS7).

8-82. A1 CONNECTOR BOARD TROUBLESHOOTING

WARNING
HIGH VOLTAGE IS PRESENT ON A1J4 IF THE LASER IS ON AND THE
TUBE CONNECTOR IS NOT CONNECTED TO A1J4.
8-83. Use the schematic diagram
A1F1 or A1F2 is open. Check for proper transmission of power supply voltages. Check for proper diode action across
A1CR1 and A1CR2. Check A1C1 through A1C4for shorts. Check A1R11 andA1R12.

8-84. Rear Panel LED Operational Check

WARNING
MAINTENANCE DESCRIBED HEREIN IS PERFORMED WITH POWER
SUPPLIED TO THE EQUIPMENT AND WITH THE 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).
Figure 8-20, an ohmmeter, and a voltmeter to troubleshoot A1. Check to see if
Figure 8-20.
protect the system against laser power supply
2