MKS PDR-D-1, Instruction Manual

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Chapter Five: Maintenance and Troubleshooting General Information
33
Chapter Five: Maintenance and Troubleshooting
General Information
Periodically check for wear on the cables and inspect the enclosure for visible signs of damage.
Should it become necessary to attempt repair of the unit in the field, first isolate the source of the
problem; the pressure transducer or the PDR-D unit. Any repair to the pressure transducer will
usually require a recalibration. The PDR-D unit may be repaired without calibration as long as
none of the calibration adjustments have been tampered with or changed.
How To Clean the Unit
Periodically wipe down the unit with a damp cloth.
Fault Isolation
The first approach to deal with a problem in a system is to isolate the section of the system where
the fault lies. Once this is done, the problem can be corrected. The PDR-D unit and the
associated pressure transducer can be broken down into the following sections:
•
Power Supply
•
Pressure Signal Amplification and Readout
Since a problem in the power supply will effect the performance of all sections, it is important to
begin the fault isolation at this point.
1. Measure the
±
15 Volt supplies on the pressure transducer connector. (Reference to P
Gnd.) The voltages should be within the range of 14.7 to 15.3 Volts and the AC ripple
should be less than 10 mV peak-to-peak.
2. Measure the +5 Volt supply referenced to D Gnd. The voltage should m4.75 to
5.25 Volts and the AC ripple should be below 20 mV peak-to-peak. If the voltages in
steps 1 and 2 are within the correct range, proceed to step 5. If the voltages are incorrect,
continue with step 3.
3. Disconnect the pressure transducer and repeat the voltage measurements. If the voltages
are now correct, the pressure transducer is at fault. If the voltages are still incorrect, the
problem is in the circuits of the PDR-D unit or the power supply itself.