Me again! Still working through Black Knight, trying to get it up and running correctly.

The main area of concern is the kickout at the top left isn't activating or registering balls being locked up there. So multiball never occurs and it continues to eat the balls and not put them back into play or even kick them out after a game ends.

There's also a strange scoring problem but I'm hoping that gets resolved after this switch matrix problem is licked.

The #03 switch test shows a series of problems involving 39, 38, 37, 19, 18 and 17. Occasionally it will be only some of those numbers, other times it will be the whole bunch. (Faulty wiring/shorts?)

I've disconnected the column and row connections (2J2 and 2J3) from the driver board and then manually ran through with jumpers to activate all 46 switches and had it work without issue, switches 1 through 46 all showed up properly in the diagnostics. This leads me to believe that there's a problem in the wiring or hardware. Does that seem like sound reasoning?

Cool, so provided the solder job on the headers is OK, it's safe to start tracking backwards from the connectors to the switches themselves, that's good. Primarily wanted to make sure I was safe to isolate the playfield tech after testing the switch logic manually.

I do have the switch matrix chart but like a dumb dumb I'd left it in a binder that I didn't have with me. So that will have to wait until next time.

Schertz, if I'm understanding your suggested method correctly, that means the switches are wired in series, yes? Is there a ground wire that hits each switch as well? Apologies, I don't have the machine right here so I'm trying to remember what I was looking at. I don't recall seeing any solid coloured wires that I'd normally associate as a ground, but there are so many wires I wouldn't be surprised to find out I missed seeing it.

That sounds like an accurate summary Terry, yes.

I have not touched any of the playfield electronics yet, my adventures have been confined solely to the backbox.

I don't know how to accurately answer your question, so I'll describe what I did, maybe that'll communicate the right info.

With the glass off but the machine otherwise undisturbed, I flipped up the playfield and visually inspected the bottom, taking care to touch as little as possible. No "work" was done at this time, just visual inspection.

Dropped the playfield back down and ran the switch test with it fully connected. This produced the conflicts mentioned already.

I turned it off again, flipped the playfield up and then back down and after powering it up and running through the switch tests, similar results occurred. I don't remember the exact order, if the 17,18 and 19 switches were closed or if that happened the first time, either way, through some combination of my eyes looking at them or the shifting of the playfield, that changed the locked switches showing in the test.

I then disconnected 2J2 and 2J3 from the driver board. Powered the machine on, put it into the switch test and since the playfield switches were disconnected, there were no switch conflicts/locks showing. I then went through and sequentially tested the switches from 1 to 46 via a jumper wire connected between the various pins on 2J2 and 2J3 successfully.

That's a really good suggestion, I will totally do that.

Quick clarification question.

I'll remove the balls and enter switch diagnostic mode.

If it's constantly cycling between the closed switches (39, 38, 37, 19, 18 and 17) will I be able to manually activate and test the other switches? I assume I should be able to, but I want to make sure I'm understanding the suggested testing process.

The switches are cycling without any input from me at all. Like the minute I initiate the switch matrix test (which is test #03 in the credits display, probably where things got confused the numbers (39, 38, 37, 19, 18 and 17) flash on the display continuously.

I'm sure that's likely an obvious tell to someone but it's literally my first attempt at diagnosing a switch matrix issue. To me, after reading the Operators Handbook again, it sounds like the switches in question or some combination thereof are stuck in a closed state, if they were to open, it sounds like they would disappear from the cycling sequence.

So I think I need to figure out what's causing those switches to remain in a closed state.

Hahaha shit, I'd never even thought of that! Good lord. Oh well, humility is a wonderful thing, sometimes it just takes a while for life to drill it into your damn head.

I'll probably have to wait until the weekend to take a look at it, but I appreciate all the advice and clarification that's been provided so far.

It looks like all the switch conflicts that were visible during my first round of testing were in fact, as a result of the balls being in the trough and various drop targets being down. Doh!

That being said, there's still issues with the game and its scoring. During games the score goes hog wild and claims I've made 1 million points (or more) and have increasingly large numbers of credits input, despite barely scoring anything on the table.

Just wanted to bump this and see if anyone had some ideas of where I could start looking.

No switches are showing as closed during the switch test. I (sheepishly) was getting false positives by forgetting that balls in the game and drop targets not being up would close switches. Oops.

I've removed all the balls and reset all the drop targets. I've manually activated every switch, one at a time, and the corresponding proper switch activates during the test.

During games, the score still glitches out and jumps up WAY faster than it should.

Thanks Terry (and HHaase), I'll plug away at that for a while and update if I come up with any more info.

Well I know that (before I removed the striker) the bell was ringing WAY more than it should have. I'll pay more attention to what's happening in the game and the scoring increases next time and report back.

The ball lock in the upper playfield issue sounds like it might be a possibility. The first ball position switch seems to work well, but the second and third don't register unless the switch wire is pushed WAY down, so if the wire isn't kept in the exactly correct spot, the switch would maybe register as being open/closed far too often during play.

Back with a small update of symptoms that crop up while playing.

The scoring seems to predominantly jump by a million points.
The BK voice will often interrupt a ball mid-play with.
The lower cabinet bell will ring far too often, I assume that's resulting from the score blowing up so much, but I don't have a good handle on the scoring rules to determine if that's just working correctly based off the score increasing or if that's another symptom.
The player 1 score display LCD has a flicker and occasionally drops digits during a game, yet it tests 100% solid when the machine is in diagnostic mode.

The drop targets are all physically being reset after they've been downed, single, double or all three, so that appears to be working correctly from a mechanical standpoint.
The top left ball lock kick-out is working, the switches in that trough needed adjusting so they'd actually register balls sitting on them. They now work every time. Overall, like I said, mechanically, the game appears to be playing correctly.

Like before, when booted up in diagnostic mode, no switches are showing as open and I can manually activate each individual switch and the board recognizes it and only it as being active and displays it correctly on the LCD.

Ok cool, that likely suggests that the bell is ringing at the correct time then, but that the multiplier is maxing out improperly.

As an addendum to the symptoms, the BK will often speak during games and say something along the lines of
'I cannot fight you again. you win.'
'one enemy cannot fight the black knight. Will you challenge the black knight again?'

Meanwhile gameplay continues along with scoring (incorrectly)

Disconnected the coin door harness, no change in behavior.

Also, oddly enough, tried not playing the game at all.

Put in a credit, pressed start shot the ball and once it cleared the gate on the upper playfield I took the ball out of the game completely. After about a minute, the crowd sound effect engaged so you heard cheering, the score jumped to 1,000,100 and Black Knight says "I cannot fight you" as that trips the Replay score.

No switch was ever tripped (save the shooter lane) and the machine was not touched or bumped. In diagnostic mode, still no switch is showing as being open.

Any thoughts?

Hot off the presses update:

If the "mystery" switch when the ball rolls down the left inside roller is pressed and I trip the corresponding "mystery" roll under switch on the ramp to the upper playfield, all of the backbox LCDs go out, none of the switches work, the game essentially hard locks and whatever sound is playing at the time loops for eternity, or until I shut the game off and turn it on again, at which point, everything appears fine and I'm able to start another round.

Which is fun...

Both of those switches test perfectly fine on their own, or in tandem, during diagnostics.

Bumpity bump in case the update got missed.

Not sure if these symptoms are related or not. Wish I had a better grasp of troubleshooting the switch matrix. Also working on it when it's at someone else's house is tedious at best.

I should be able to update with a video in a bit.

I've got an original owner's manual and the schematics are in very good shape. But by all means, I'd love to see if there's anything you've got that I'm missing. Shoot me a PM.

Here's the video of the gameplay oddities I was talking about.

Before I really start taking things apart and removing switches... my buddy asked if the behaviour I've detailed and recorded could be as a result of a problem on the PCBs and not due to faulty playfield wiring.

I said I was about 60% confident that the problem exists somewhere in and around the playfield, be it the wiring harness or a blown diode or faulty switch, but since I have so little experience dealing with this kind of problem, I figured I'd ask here.

Experts, if you had to hedge your bets and start troubleshooting this game in its current state (all other things being equal and knowing that I've run through the power supply board, MPU and driver boards) would you start looking at the playfield, or in the backbox?

If I'm understanding you correctly, I believe I've already done that.

I ran through them from 1-46 without any errors. Each jumper combination correctly closed the associated switch as displayed in the test output LCD. To me that means the boards are working and the issue is with the physical components on the play field. But like I said, I'm inexperienced and was making sure before answering my friend that what I was claiming was actually correct.

40 pin interconnect has been entirely replaced with new kit. Connections for the switch matrix have not been replaced, but have had the solder re-flowed.

Going to bump this again with another question that may or may not be related to the switch matrix.

All the 7 segment displays test 100% perfectly during the system audit display test. During gameplay and while sitting in audit mode, the displays in the 1st player and game+credit windows have some segments that will flicker on or off and occasionally will not display their number altogether.

I'm currently assuming there may be an issue with the power supply board and will be replacing all the connections. I was also wondering if the odd random scoring behavior, may be as a result of an underlying power issue, and not one of the switch matrix at all? During games, sections of the display will flicker on and off and yet everything tests fine during the audit mode display tests.

Any thoughts?

Cool thanks. Time to do some more soldering.

As a quick update, I've completely removed every single .156" male connector on the MPU, Driver and Sound boards and replaced them with updated square pin new ones. The new and clean solder and appropriately long solder side tails look miles better than the original work. I should be able to test them out tonight.

I'll update later with the results.

Thanks for the continued input, it's always appreciated.

So I've got some good news and some bad news.

Good news first: Repinning all the male connectors appears to have completely resolved the goofy display problems/signals that were plaguing previous testing. The half hour spent noodling around with the game produced absolutely no display errors or half-lit segments, which is great. I can cross that off my list of things that need seeing to.

Bad news: Repinning the connectors appears to have had no effect on the odd scoring problem. As before, the game will play normally for a time and then tack on an extra 1,000,000 or 3,000,000 points instantly.

Disclaimer: I haven't yet tested any of the switch matrix diodes, and I haven't replaced the female connectors that connect the switch matrix to the driver board.

I've included a video of questionable quality in an effort to help describe the problem. Jump to 34 seconds to see the errors and avoid hearing my son yell

Warning/apology, the angle and steadiness is a direct result of having only one available arm to hold my phone.

Is it worth my time to try and test every single diode on all the switches do you think? Like my next step is either that, or replace some of the 740X chips on the driver board ... ???