Fluke Biomedical 945A - Manual (Page 45)

Power for the detector is normally provided by the electronic high voltage power supply ( jumper 5 in
position B to C). However, high voltage can be supplied to the detector by connecting battery terminals 1
(+) and 2 (-) of J7, and placing jumper 5 in the A to B position.
The high voltage board has a 100 to 1 voltage divider circuit which permits monitoring high voltage
through operational amplifier U15 on TP5 with an ordinary voltmeter (10 Meg impedance), without loading
down the high voltage circuit or requiring the use of a high impedance probe. The high voltage
adjustment is provided by R118. Refer to section 5 for adjustment instructions and precautions.
The following LEDs are provided to indicate operation of certain functions of the 977-210-10 board:
LED # Indicates
LED1 The presence of +15 Vdc supplied to the
circuit board from the UDR
LED2 Communications - Receive
LED4 Regulated +12 Vdc is supplied to the
electronic high voltage circuit
LED5 High voltage is present at J6
Test points are provided on the high voltage board as follows:
Test Point Function
TP3 High Voltage 1:1
TP4 DC Ground
TP5 High voltage divided by 100
NOTE
TP1 and TP2 are not installed on the 977-210-10 circuit board.
A 0 - 10 Vdc analog output signal is obtained from an 8 bit D/A converter U7 and operational amplifier
U11. JMP4 controls the operation of the analog output. This output is normally used to drive a local
meter or display. The analog output is logarithmic.
Transistors Q13, Q101, Q103, and Q102 are used to provide a -15 Vdc output voltage to drive a local
alarm. The normal state of the output (energized or de-energized) is selectable via jumper JMP3.
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