MKS Granville-Phillips Mini-Convectron 275 series, Инструкция по эксплуатации

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Chapter 5
48
Mini-Convectron Module with RS-485
Instruction Manual - 275545
5.4 Symptoms and Possible
Causes
Table 5-1 General Symptoms/Possible Causes
Symptom Possible Causes
No power indication No input power.
Verify that there is +11 Vdc to +16 Vdc at pin 3 of the I/O connector with respect
to pin 4.
Bridge analog output voltage reads less
than +0.22 Vdc or greater than
+10 Vdc 1. Gauge tube failure. Test for gauge tube failure. Measure the resistance between
the following terminals with the gauge tube at atmospheric pressure and an
ohmmeter which cannot apply more than 10 mA.
• Pins 1 to 2: 18 to 23 ohms
• Pins 2 to 3: 50 to 60 ohms
• Pins 1 to 5: 175 to 190 ohms
If the resistance from pins 1 to 2 reads about 800 ohms, the sensor wire in the
gauge is broken. Replace the gauge tube.
2. Bridge amplifier failure. All of this circuitry is located on the small PC board
that the gauge tube plugs into. Check for input power to this board across the
two outside fingers of the small board where it is soldered into the large board.
Check that the bridge output voltage between the middle finger and the bottom
finger is approximately 6 Vdc with the gauge tube at atmosphere.
2
4 1
5
3