38874R4.S - Circuit Board Installation Instructions
PDF Instructions for replacing the 38874R4.S circuit board
PDF Instructions for resetting the limits after replacing the 38874R4.S circuit board
38874R4.S DC Control Board Replacement
These instructions are written assuming that you will have ample room around Opener to perform this repair. Some rare instances will require removal of the unit from its mounting hardware and repair made on a bench or floor. Refer to your Owner’s Manual for proper assembly and carefully read and understand all warnings and cautions pertaining to your unit.
BE SURE ELECTRICAL POWER HAS BEEN DISCONNECTED FROM THE INPUT POWER LINES PRIOR TO REMOVING THE MOTOR COVER.
ANY AND ALL REPAIRS MADE TO THIS UNIT MUST BE PERFORMED WITH THE DOOR DISCONNECTED FROM THE OPENER AND IN THE CLOSED POSITION.
1. Pull emergency release cord on the carriage to disengage opener to close the door if necessary. (If unable to lower door using the garage door opener, use extreme caution manually closing the door. Before pulling the red emergency release cord, make certain people and objects are clear of the door opening.)
2. Unplug the opener power cord from power receptacle.
3. Open lens cover by pressing middle tab inward and remove light bulbs. FIG. 1.
4. Remove wall control and Safe-T-Beam wires from the terminal block located on side of opener FIG. 1. Use a small common screwdriver to press in on orange tabs while gently pulling wires from the terminal block. Marking the wires can help facilitate replacement.
5. Unplug any optional accessories such as a battery backup and/or network adapter.
6. Remove the two 5/16” screws securing powerhead cover to chassis. FIG. 2.
7. Allow the motor cover to swing down to access control board and wire harnesses.
8. Unplug the following harnesses from the control board. FIG. 4.
• Light harness
• Motor harness
• Opto harness (see step 12-13)
• AC IN harness
• Motion Detector harness (if equipped)
• Green ground wire to chassis (if equipped).
REMOVE AND DISCARD.
9. Powerhead cover can now be removed from opener chassis for repair. (If equipped) Special care should be taken to prevent damage to the motion detector bulb located on the bottom of the motor cover.
10. Remove the three control board mounting screws and the old control board. FIG 3.
11. Feed the new antenna wire through the hole in the cover. Mount the new replacement control board 38874R3.S to the cover and secure with the three screws removed in step 10.
--- SEE BELOW FOR MOTOR TYPES ---
12. If your motor compares to MOTOR TYPE 1. Remove existing harness from the motor and plug pre-installed OPTO SENSOR harness from new control board directly into the motor.
13. If your motor compares to MOTOR TYPE 2. Remove pre-installed OPTO SENSOR harness from the control board and plug existing OPTO harness from the motor into DUAL ENCODER OPTO SENSOR plug on replacement control board. (Or use new harness packed with control board).
14. Hang powerhead cover to chassis to connect all other harnesses that were removed in step 8.
15. Swing the powerhead cover up onto the chassis and secure using the screws that were removed in step 6.
16. Install wall control and Safe-T-Beam wires. Install battery backup and/or network harnesses if applicable.
17. Install light bulbs and close lens cover.
18. Reapply power to the opener.
19. Limit controls, transmitters, and full function test will be required. Refer to your owner’s manual and/or assembly poster for more detailed information