Model 755R
Instruction Manual
SECTION 6
MAINTENANCE AND SERVICE
The information provided in this section will aid in isolation of a malfunction to a particular assembly or circuit board. A few detailed checks are included, to aide in locating the defective assembly.
It is recommended that those familiar with circuit analysis, refer to Section 6 Circuit Analysis of this manual.
WARNING
ELECTRICAL SHOCK HAZARD
Do not operate without doors and covers secure. Servicing requires access to live parts which can cause death or serious injury. Refer servicing to qualified per- sonnel.
For safety and proper performance this instrument must be connected to a properly grounded
Optional alarm switching relay contacts wired to separate power sources must be disconnected before servicing.
WARNING
PARTS INTEGRITY
Tampering or unauthorized substitution of components may adversely affect safety of this product. Use only factory documented components for repair
If instrument readings do not meet specifica- tions, the first step in troubleshooting is to isolate the analyzer from the sample stream and the sample handling system.
Admit zero and span standard gases to the analyzer. Observe readout on digital display, and on recorder, if used.
Digital display gives correct reading with standard gases, but not with sample gas
The sample and the sample handling system are suspect. Check these areas.
Digital display gives correct readings with standard gases, but the alarm or output devices do not
Check these devices individually.
Digital display gives overrange readings with standard gases, as well as sample gas
The problem is likely with detector or the electronic circuitry. Turn power OFF. Tap detector compartment with fingers, wait 30 seconds, reapply power. If the suspension within the detector assembly is hung up, this may correct the problem. If not, proceed with checks of the detector and electronic circuitry.
Digital display gives erratic readings with standard gases, as well as sample gas
If zero and span standard gases give noisy or drifting readings, the problem is probably in the detector or the temperature control cir- cuits. Proceed with checks of the detector and electronics. In general, before concluding that the detector is defective and must be re- placed, verify correct operation of all circuits that could cause erratic readings.
a.Control Board Checkout
The Detector Isolation Plug located on the Control Board (Figure
Voltage
1. Set RANGE Select to lowest range.
Rosemount Analytical Inc. A Division of Emerson Process Management | Maintenance and Service |