Alright, I've reached the point of confusion and need some help as to what to do next on the Comet I'm working on. I've got two separate issues, a switch matrix issue and a special solenoid issue.
Switch Matrix Issue: Originally the game was missing the transistor and single resistor below IJ8 for column 5. Column 4 wire was disconnected entirely. There was obviously some burning issues in this area and SR9 resistor bank was a little toasty as well.
What I've done: Replaced transistors and resistors in both column 4 and 5. Also replaced SR9 and SR8. Put the wire back in the IDC on column 4.
Column 5 works perfect now. However any switch activated in column 4 activates all switches on that row. Removed the connector and tested using the in-game switch test and jumpers to isolate that it is in fact a board issue. As I'm not really versed on logic probes yet my next step is to just keep going up the chain replacing things (which I know isnt a great idea but I'm not sure what else to do). Next up the chain would be U45 (a 74LS244), then U15 (a 6820/6821 PIA), then over to U51 & U52 (MC14011) and finally SR16 (another resistor bank). Any ideas here?
On to the special solendoids: Again, there was some burning here and I have replaced one TIP102 that was shorted and two of the pre-drive transistors. All test fine now. In addition, an entire trace running from the center of one transistor to the connector pin was removed/lifted and I bridged it with a jumper wire. (I believe this was the right kicker).
The right kicker locks on when the game is turned on. I removed the diode from the coil under the playfield, tested it (tested fine), and then replaced it. At the same time I removed a wire from one lug of the coil so I could test the other 5 special solenoids. Both the left bumper and bottom bumper do not work when manually pressed. I havent checked the voltage on them yet as I had to get some sleep last night but that's where I'm at right now. Looking at possibly U6 and U7, appears they were already replaced at some point but perhaps incorrectly (wouldnt surprise me with this board)
Last issue, the K1 relay activates and never deactivates when the game is powered on, so you always have flippers even in attract mode. I tested the transistor for this as well and it tests fine.
Any help is appreciated, sorry for the novel.