Thermo Scientific Micro-Tech 9101 - Page 101

Maintenance and Troubleshooting
Load-Cell Problems
Thermo Fisher Scientific Micro-Tech 9101/9201 Reference Manual, Rev J 4-7
1. Verify load-cell excitation voltage. Is excitation voltage (terminals 2
and 3 of J16 and/or J21) 5VDC?
 If NO—Disconnect all load-cell wires and recheck. If excitation
voltage is now good, check load cell and field wiring.
 If YES—Proceed to verify load cell sense voltage (see step 2).
2. Verify load-cell sense voltage. Is sense voltage (terminals 4 and 5 of
J16 and/or J21) 5VDC?
 If NO—Verify proper position of sense jumpers (see page A-28).
 If YES—Proceed to verify load cell mV output (see step 3).
3. Verify load-cell mV output(s). Is load-cell mV output within range
of mV/V at MT9000 (terminals 6 and 7 of J16 and/or J21)?
 If NO—Disconnect load-cell signal wires. Recheck mV at the
disconnected wires. If still outside mV/V range, proceed to verify
load-cell mV output at junction box.
 If YES—Load-cell circuitry is good.
4. Verify load-cell mV output at junction box. Disconnect load-cell
signal wires from junction box. (terminals 22 and 23). Is load cell
mV output within range of mV/V?
 If NO—Replace load cell.
 If YES—Load-cell circuitry is good.