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Model T101 Instruction Manual Troubleshooting & Service
229
Table 9-6. Relay Board Control Devices
FUNCTION CONTROL DEVICE SOCKETED
Valve0 – Valve3 U5 Yes
Valve4 – Valve7 U6 Yes
All heaters K1-K5 Yes
9.5.9. MOTHERBOARD
9.5.9.1. A/D functions
A basic check of the analog to digital (A/D) converter operation on the motherboard is
to use the Signal I/O function under the DIAG menu. Check the following two A/D
reference voltages and input signals that can be easily measured with a voltmeter.
Using the Signal I/O function (Section 4.6.1 and Appendix D), view the
value of REF_4096_MV and REF_GND. If these signals are within 10
mV and 3 mV, respectively, of their nominal values (4096 and 0) and are
stable to within ±0.5 mV, the basic A/D converter is functioning properly.
If these values fluctuate largely or are off by more than specified above,
one or more of the analog circuits may be overloaded or the
motherboard may be faulty.
Choose one parameter in the Signal I/O function such as
SAMPLE_PRESSURE (see previous section on how to measure it).
Compare its actual voltage with the voltage displayed through the
SIGNAL I/O function. If the wiring is intact but there is a difference of
more than ±10 mV between the measured and displayed voltage, the
motherboard may be faulty.
9.5.9.2. Analog Output Voltages
To verify that the analog outputs are working properly, connect a voltmeter to the output
in question and perform an analog output step test as described in Section 4.6.2.
For each of th
e steps, taking into account any offset that may have been programmed
into the channel (Section 4.6.3.4), the output should be within 1% of the nominal value
listed in t
h
e table below except for the 0% step, which should be within 2-3 mV. If one
or more of the steps is outside of this range, a failure of one or both D/A converters and
their associated circuitry on the motherboard is likely.
Table 9-7. Analog Output Test Function - Nominal Values
FULL SCALE OUTPUT VOLTAGE
100MV 1V 5V 10V
STEP % NOMINAL OUTPUT VOLTAGE
1 0 0 mV 0 0 0
2 20 20 mV 0.2 1 2
3 40 40 mV 0.4 2 4
4 60 60 mV 0.6 3 6
5 80 80 mV 0.8 4 8
6 100 100 mV 1.0 5 10
07266B DCN6485