6.3.7
Keyboard/
Interlock PCB
Chapter 6 - Detailed Diagnostics
continued
Replacement:
1.
Remove the line cord and all cabling leading to the generator PCB.
2.
Remove the two phillips head screws holding the processor in the service configuration and the six screws
securing the generator PCB to the aluminum bracket.
3.
Remove the PCB and replace it with the appropriate part listed in Appendix C.
NOTE: Once the generator PCB is removed, remove and save the four standoffs which support the
microprocessor PCB.
The keyboard PCB is mounted to the front panel assembly and receives inputs from J6 and J5 on the generator
PCB, the Foot Switch and Hand Piece. For a functional description see section 2.2.
With the exception of the functionality of the interlock circuit, all other keyboard functions have been tested in
sections 5.2 and 5.3. In these sections, all of the buttons and LEDs were exercised. If certain buttons or LEDs do not
work, sequentially re-test the keyboard with a substitute foot switch and microprocessor PCB before replacing it.
Caution: During this testing the instrument blade will have some minimal activity.
Verify that the interlock portion of this PCB is working properly, as follows:
1.
Access the first page of the software diagnostic mode as described in section 5.2, and diagrammed in
Appendix A.
2.
Press the Standby Button twice to access the third page of the service mode. Press the blade firmly into
wax, wood, or cardboard and verify that the reported relative voltage increases in excess of 100%
whenever a foot pedal is pressed.
3.
If no variation is noticed, it indicates that the interlock is either not releasing or never engaging. In either
case, replace the keyboard PCB.
NOTE: Before replacing the keyboard, check the continuity in the 10 conductor ribbon cable leading from the
generator PCB to the keyboard.
Replacement:
1.
Remove the line cord and un-screw the two phillips head screws which hold the front panel "L" brackets to
the base plate.
2.
Loosen the two phillips head screws that hold the front panel to the generator and remove the front panel
by lifting it up and away from the generator.
3.
Remove the two nuts and lock washers bolting the audio annunciator to the front panel and de-solder the
three wires leading to the foot switch connector on the rear panel.
4.
Remove the seven phillips head screws securing the keyboard to the front panel. Remove the PCB and
replace it with the appropriate part listed in Appendix C.
23
6.3.6
Generator PCB,
continued
