BNC 130 - Manual (Page 28)

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MAINTENANCE AND CALIBRATION
• BNC terminated 30 ohm coaxial cables, 1 meter length.
• Variable dc voltage source (capable of ±3 V into 30 ohms).
• Single-mode optical fiber patch cord terminated with appropriate connectors..
PROCEDURE
Note: This calibration should be carried out in the order presented.
Before starting, verify that the power supply voltages are at their nominal levels (+12 V ±0.1 V, -12 V
±0.1 V, +5 V ±0.05 V, and -5-2 V ±0.05 V) with the Module plugged in. Operate the Module on extension
cables.
Module Interface DAC Calibration
Refer to Schematic 6040-35 (PCB 6040-4). Set the Mode to Pulse; set the Peak and Baseline levels both
to 1.000 mW; set the Trigger to External Drive with a threshold of +2.50 V.
Connect the DVM between TPG (A GND) and Z9-1.
Adjust R3 for a voltage of -5-000 V ±2 mV.
Connect the DVM between TPG (A GND) and Z8-7.
Adjust R4 for a voltage of -4.000 V ±2 mV.
Connect the DVM between TPG (A GND) and Z8-7,
Adjust R5 for a voltage of -4.000 V ±2 mV.
External Drive Discriminator
All further measurements and adjustments refer to the Laser Output board. Schematic 155-31 (PCB 155-
1).
Set the Mode to Pulse. Set Trigger to External Drive with a threshold of +0,99 V. Connect the DVM to
Z18-1 (Schematic 155-31, sheet 2) and record the voltage. Now set the threshold for -0.99 V. Adjust
R141 so that the DVM reading exactly complements the recorded value.
Connect a +1.00 V dc supply to the module EXT DR connector. Connect the DVM to Z5-8. Scan the
TRIG External Drive threshold parameter from 0.90 V to +1.10 V and verify that Z5-8 changes from low
to high (-1.7 V to -0.8 V) when the threshold voltage is set for 1.00 V ±30mV.