More work on the operator control panel of drive B

REPLACING BROKEN DENSITY BUTTON

I installed a mini pushbutton switch on stiff leads into the PCB, after removing the broken switch. Simple and easy fix. This hides behind the operator control panel in normal operation thus I didn't need to find the same or cosmetically similar switch.

Replaced Density pushbutton switch on the operator control panel PCB

VERIFYING THE PUSHBUTTON LOGIC WORKS

First step was to beep out the connections between J1 that connects the drive motherboard and J2 which connects to the pushbuttons and lights on the panel. It was important to verify that I knew what was connected directly and what was driven by the flip flop that recorded the Online status of the drive.

I then did some beeping out of wiring on the backplane to identify places to read switch state and to command light activation. I wanted pins well enough separated for easy access with the probes and other wires.

The sequence of testing planned is:

1. verify that the 'start state' line on J4 pin 3 was high when I powered up
2. verify that the Reset button connected ground and J4 pin 4 when pushed
3. verify that the Unload button connected ground and J4 pin 5 when pushed
4. verify that the Load/Rewind button connected ground and J4 pin 7 when pushed
5. verify that pushing the Start button changed J4 pin 3 to low
6. verify that pushing Unload doesn't connect ground to J4 pin 5
7. verify that pushing Load/Rewind doesn't connect ground to J4 pin 7
8. verify that SW1 toggled to offline and back to online causes J4 pin 3 to go high again
9. verify that the Power lamp is always illuminated
10. verify that grounding J4 pin 17 turns on the Select light
11. verify that grounding J4 pin 11 turns on the Load Point light
12. verify that grounding J4 pin 9 turns on the Load Check light
13. verify that grounding J4 pin 15 turns on the Ready light
14. verify that grounding J4 pin 10 turns on the End of Tape light
15. verify that grounding J4 pin 12 turns on the File Protect light
16. verify that pushing the Density switch on the PCB will connect ground and J4 pin 1

Status of first set of tests:

1. Failed - no signal seen on pin 3
2. Success
3. Failed - no connectivity
4. Failed - no connectivity
5. Failed - no signal on pin 3
6. Failed - no connectivity
7. Failed - no connectivity
8. Failed - no connectivity
9. Success
10. Success
11. Success
12. Success
13. Failed - no light
14. Success
15. Success
16. Success

Moving a VOM directly to the flip flop I did see that the Start push-button turned it HIGH and SW1 toggled to offline toggled it LOW, so indirectly I confirmed tests 5 and 8. However, something is still wrong as the signal isn't reaching J4 on the motherboard via the cable from J1 on the operator control panel PCB.