Fluke 875 manual Troubleshooting

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Maintenance, Calibration, and Troubleshooting

Troubleshooting 5

5.3 Troubleshooting

The 875 High-Range Containment Monitor is safety-related equipment. The monitor has been assembled by techniques and with parts selected for the reliability required in a nuclear application. Any repairs made to the detector or readout (other than replacement of parts listed in Section 5) may void the safety-related rating. The troubleshooting procedure that follows is a guide to isolating a fault in the system.

Replacement of parts is at the printed circuit board level only. Printed circuit boards must be returned to Fluke Biomedical for service.

There are two self-contained system tests available in Containment Monitor 875, the Channel Test and the ECS Test. In both cases, the procedure is to put a known input into the system, and to look for the desired output.

There is an important difference between the Channel Test and the ECS Test: the former applies an input to the readout module (that is, to the first electronic circuit in the Containment Monitor); however, it does not test the detector or the cables connecting the detector to the readout module. In addition, the Channel Test applies a DC voltage, whereas the ECS Test applies a ramp voltage to the detector plates, monitoring the resultant current into the readout module.

The digital multimeter mentioned in Table 5-1 of the calibration section is also recommended for troubleshooting.

If the ECS Test gives a favorable result, the following conditions exist:

1.The detector cannot have any appreciable malfunction.

2.The cables must have continuity.

3.The ECS board and power supply board must be operative.

4.It is highly improbable that any malfunction exists in the fail/safe circuitry.

5.The amplifier, meter and alarm circuitry must be operative.

Essentially, the Channel Test verifies only #5 of the above. However, in doing so, it incidentally verifies all of the power supplies except the high voltage power supply.

For clarity, troubleshooting is divided into six divisions:

1.Power supplies

2.Input circuit

3.Meter circuit

4.Alarm circuits

5.ECS board

6.Overall fail circuitry

NOTE

Disconnect Detector 877-1 from Readout Module 876A-1 by removing cables from J1 and J2 before starting troubleshooting of readout module. The user will probably wish to disconnect the external alarms as well. It is the responsibility of the user to see that the alarms are not set off by disconnection.

5-3

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Contents High Range Containment Monitor VictoreenFluke Biomedical Table of Contents Calibration and Test Procedures Introduction SpecificationsGeneral Description Containment MonitorReadout Module 876A-1 Temperature Operating 40 to 120F 4 to 49CEquipment Overview High-Range Containment Monitor DetectorRack Chassis Cables/Connectors/Panel Pull Box AssemblyFlexible Tubing 878-12-30TAB Optional EquipmentHigh-Range Containment Monitor Typical Energy Response Curve Detector Typical Linearity Detector Receiving Inspection High-Range Detector, Recommended InstallationStorage Procedures, Warnings, and CautionsBlank Installation InstallationReadout Module Pull BoxCable Sealing Specifications for CableDetector Test After Installation Cable and Wiring InstallationSpecifications for Cable Detector Cable Inside ContainmentAll Alarms on P2 Normal Operation Shelf State Ancillary WiringPower Connections P1 Computer & RecorderOperation OperationVictoreen Function Description Functional DescriptionReadout Module 876A-1 Negative Power Supply High Voltage Power Supply Normal Operation non-ECS Test FAIL/SAFE Comparison Circuit on Power Supply BoardOperation of High Voltage Supply During ECS Test Alert Alarm Circuit High Alarm CircuitFail/Safe Circuit Recorders and Computer BuffersPen Clamp Meter at extreme lower end of scale Panel Meter Action During ECS TestAction of Green Safe/Reset Light and Alarm During ECS Test Low Voltage Ramp GeneratorMonitoring Circuits of The ECS Board Block Diagram of ECS Test Muting Circuits of ECS Board Safe/Reset Sub-circuitsBlank Maintenance, Calibration, and Troubleshooting MaintenanceCalibration Test Procedure TP876A-1-108 Troubleshooting Mother Board P/N 876-1-78, Schematic 876-1-3A Signal Input CircuitPreamplifierIMeter Board P/N 876A-1-86, Schematic 876A-1-3E Rear PanelTest Point Normal Channel Test TP501 TP502 +6.3High Alarm Circuit Muting Stages of the Alarm CircuitsNormal Low Signal Level Channel Test ESC Board P/N 876A-1-92, Schematic 876A-1-3D Wave Shapes on the Electronic Check Source Board Starting With Pins M and P on the Power Supply Schematic Overall Fail Circuitry Associated with the ECS TestStarting With Terminal H on Relay Driver Board Operation of the Latch Circuit Outputs of U206 Pulse Generator on the ECS BoardCircuit assumed initially in Pass Condition Fail Condition Latch CircuitPin Voltage State Comments NORCalibration and Test Procedures Blank Cable and Pull Box Procedures Cable and Pull Box ProceduresVictoreen Applicable Drawings and Bill of Materials Applicable DrawingsDocument Number Description Detector Cable Out of Containment Applicable Bill of Materials Fluke Biomedical
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