Welch Allyn Wall Transformer 76712

Refer to clock instructions in manual PN767036, pg. 5 & 6 for replacing clock battery and changing time.

Remove clock assembly from 767 and turn it over.

Remove three Phillips head screws using a #1 Phillips screwdriver.

Remove clock module from face-plate.

Did the set buttons come off during disassembly?

Replace the battery located on the underside of the clock module.

Apply calibrated resistance to handle stud using a 5 ohm power resistor (5 watts) in parallel with a 5-10 ohm potentiometer

Adjust potentiometer until current delivered is 750 mA (4.66 ohm nominal load)

Measure output voltage (rheostat full on) using a true RMS meter set on DC scale. Expected: 3.5 VDC +/-0.5 VDC

Measure third handle outlet output at slot jacks on right end of main unit. Expected: 7 VAC +/-1 VAC with nominal load of 9.33 ohms

Disconnect wall transformer from mains before servicing

Unscrew six Phillips head screws on the back of the 767 using a Phillips #2 screwdriver with a 3" (minimum) shank

Position the 767 on its back and separate the MH-Front from the MH-Back

Ensure housings are not pulled apart abruptly to avoid pulling wires and connectors

Slide the wire tie off of the MH-Back standoff

Ensure all primary components are replaced

Connect the Welch Allyn tester T-13251

Is the ground leakage current less than 50 microamps?

Test between the following parts

Disconnect wall transformer from mains before servicing

Follow instructions in Section B-1 to remove MH-Front

Ensure blue connectors on emitter and detector pins are not disconnected

Squeeze the plastic spring clips on the sides of the switch to force it out of the MH-Front