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Okuma OSP Controller
Safety · Intermediate
Okuma OSP Alarm D 4873 - Door open/close limit switch NG
An abnormality occurred in the limit switches used to confirm the open/close state of the front door. Code 1 means the door open confirmation and door close confirmation signals turned ON at the same time, which is physically impossible and indicates a faulty switch or wiring.
4873
Okuma OSP Alarm D 4873 - Door open/close limit switch NG
Door open/close limit switch NG
An abnormality occurred in the limit switches used to confirm the open/close state of the front door. Code 1 means the door open confirmation and door close confirmation signals turned ON at the same time, which is physically impossible and indicates a faulty switch or wiring.
Common Causes
- Faulty door open/close confirmation limit switch on a mechanical locking type door
- Wiring short causing both confirmation signals to read ON together
- Misadjusted switch actuator making both switches at once
Troubleshooting Steps
- 1Read the code number shown with the alarm: code 1 = Door open confirmation and door close confirmation signals ON at the same time
- 2Read the code: 1 means the door open confirmation and door close confirmation signals turned ON at the same time.
- 3Watch the door open and close confirmation inputs on the I/O check screen while operating the front door slowly; only one should be ON at each end of travel.
- 4Inspect the limit switches for the mechanical locking door open/close confirmation: check for a sticking plunger, coolant ingress, or a loose actuator.
- 5Check the switch wiring for a short between the open and close signal lines.
- 6Change the faulty limit switch for mechanical locking door open/close confirmation as the manual directs.
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