Fluke Biomedical 945A - Manual (Page 73)

Auto-Zero Adjustment Procedure:
1.
Turn OFF the power to the unit when you change any jumpers or you change operating firmware.
Use caution when in close proximity to the red coaxial lead on the 977-200-15 board; the red coax
lead is the electrometer input and is static sensitive.
2.
When the power is OFF, replace the operating firmware (found in the Z10 location with numerical
label on it) with the test firmware labeled 977 TEST V10. Make sure it’s inserted correctly - pin 1
should be pointing toward the TP7 test point on the 977-200-15 board.
3.
Move the JMP1 jumper block (found in the lower right corner of the 977-210-10 board when viewed
from the connector end) to the B - C position or outward toward the edge of the board. This jumper
block determines which communication driver is active and B - C position activates the RS-232 port
on J4 (next to JMP1).
4.
Connect your test cable between J4 and your laptop or terminal RS-232 port. Refer to the
applicable drawings in Appendix B to make this cable if unavailable.
5.
Set-up the four position DIP switch on the 977-210-10 board to match the switch the following
sequence:
Switch 1: (OFF / OPEN)
Switch 2: (OFF / OPEN)
Switch 3: (ON / CLOSED)
Switch 4: (ON / CLOSED)
6.
Move the JMP1 jumper block to the B -C position, shorting the op amp input so that the offset can
be adjusted. JMP1 is located near the two adjustment potentiometers, on the upper portion of the
977-200-15 board).
7.
Connect your digital voltmeter ground (negative lead) to TP7 and the positive lead to TP8; both
found on the 977-200-15 or upper board. Set your DVM DC range to 200 mV for a 3 1/2 digit meter
or 2 V for a 4 1/2 digit meter.
8.
Turn on power at the 946 readout. It will display an E0007 error code because the communications
port is now J4, not the VICO loop It communicates with the detector on. Your terminal should
display a menu to select from that looks like the following:
977 TEST
A-977 TEST MENU
B-MONITOR COMMANDS
SUBTEST:
If it doesn’t, recheck the terminal or laptop set-up, 977 switch and jumper block positions and your 977 to
terminal/laptop communications cable. Remember - transmit from one device should go to receive of the
other device and vice versa.
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