Technical Bulletin
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Technical Bulletin

Safety Circuit Bypass Potential

Immediate Action Required

Date

January 23, 2002 (previously distributed September 28, 2001)

Reference

122

Route to

Service Manager/Modernization Manager/Construction Manager From

MCE Technical Support Department

Equipment

MCE Control Systems shipped between late 1991 and June of 1994 with hall lantern operation. Subject controllers may have a factory modification to the HC-RB-xx (main relay board) that uses the 3G bus in place of the 3 bus to provide power for PI's and hall lanterns.

Description

MCE has recently become aware of two cases in which the 3G and 3 buses were shorted, bypassing the safety circuit.

The most likely cause has been determined to be the result of replacement or modification of the HC-RB-xx (main relay board) in the field after final inspection. Reinspection prior to returning the car to service would have disclosed improper operation of the safety circuit and the in-car stop switch.

Action

STRONGLY RECOMMENDED: During your next visit, follow the procedure below to verify proper operation of the safety circuit and the in-car stop switch:

Check the version number on the main relay board. If the number is either HC-RBH, HC-RB4, HC-RBH-xx or HC-RB4-xx (where xx indicates an alphanumeric suffix), no short potential exists, therefore no further action is necessary.


If the main relay board is NOT version HC-RBH, HC-RB4, HC-RBH-xx or HC-RB4-xx, perform one of the following tests:


  1. From inside the elevator: While the elevator is running on automatic operation, activate the in-car stop switch. The elevator should come to an immediate stop and should not respond to any calls until the stop switch is returned to the normal position.


  1. From the machine room: While on automatic operation (does not require the elevator to be running), locate the SAF relay on the HC-RB-xx (main relay board) and remove it from its socket. The "Safety LED" on the diagnostic display must turn off.

If the system passes either of the tests above (A or B), proper safety circuit operation has been confirmed and no further action is required.

If the system fails either test, action must be taken to isolate the 3 and 3G buses and restore proper safety circuit operation. Contact MCE Technical Support immediately so appropriate action can be taken.

Help

Should you require additional technical assistance:

  • Telephone 916/463-9200
  • Touch "6" for Technical Support
  • Refer to the reference number above