Quoted from skywyatt:We do have a "guy" we can call to come do his magic, but hubby would rather give it a go himself first as long as screwing it up isnt going to be painfully expensive.
Looking at your pics, your power supply connector 3J8 for the general illumination is messed up. It looks like a previous owner solved a bad connection/overheat issue by soldering the wires straight to the board, which is definitely not a good practice.
First step is to determine if you get good/correct power from the power supply board. Hopefully you have the schematics diagrams for your machine.
1. Make sure that all fuses have correct values (sometimes, previous owners make mistakes)
2. Disconnect all output connectors (3J3, 3J4, 3J5, 3J6, 3J7) and only keep 3J1, 3J2 and 3J9 connected
3. Remove Fuse F7 (since you cannot disconnect 3J8 which is hard wired)
4. Power on the machine
5. Measure your output DC voltages (be careful: the voltages for the displays are 100 volts)
6. Make sure that the +5V is not less than +5V
7. Power OFF
8. If all the DC voltages checked out, then continue with Option No. 1 below
Option No.1 - bare minimum - requires some soldering skills
1. Remove the power supply board (desolder the two wires from the 3J8 hack)
2. Reflow every connector pin to ensure good continuity
3. Replace header 3J8 with a new header
4. Buy the connector for 3J8 and rebuild it (i.e. repin the wires)
5. Re-install the power supply board (with the fuses) and connect 3J1, 3J2 and 3J9
6. Power ON
7. Recheck the output voltages and now you can also check the 6.3VAC Gen Illumination circuit
8. Power OFF
9. Plug in all the output connectors (3J3, 3J4, 3J5, 3J6, 3J7)
10. Power ON**
Option No.2 - Cadillac option - takes a lot more time, is more thorough, but a lot safer
1. Remove the power supply board (desolder the two wires from the 3J8 hack)
2. *Replace all capacitors (there are kits you can buy ready-made)
3. *Upgrade all the connectors to the four-sided pins, and replace all mating connectors by re-pinning them with the 3-sided trifurcon pins
4. *Perform the 91V mod for the display power output (91V instead of 100V will extend the life of your plasma display)
5. *Separately from the power supply, add two additional rectifier fuses that Williams should have included in the first place for the +18VDC and +28VDC circuits
6. Re-install the power supply board (with the fuses) and connect 3J1 and 3J2
7. Power ON
8. Recheck the output voltages, and now you can also check the 6.3VAC Gen Illumination circuit
9. Power OFF
10. Plug in all the connectors (3J3, 3J4, 3J5, 3J6, 3J7)
11. Power ON**
Notes:
* Vid has created a "bulletproofing" post on pinside which is a great resource for what you are asking (and a lot more) that covers these topics.
https://pinside.com/pinball/forum/topic/vids-guide-to-bulletproofing-williams-system-6
**In regard to powering the whole machine on for the first time, I would check all other aspect of your machines for evidence of problems first.
If this sounds like a bit much for you in terms of complexity and work, I would rely on your hubby's "guy" if he is capable/knowledgeable. The alternative is what I did: hours of research on pinside, reviewing the diagrams, purchasing the needed parts, getting good at soldering (lots of youtube videos out there)
Good luck, and congrats on your BK! One of the best pins out there.