Hi everyone.

I’ve got an Eight Ball Deluxe with a switch matrix issue that has me chasing my tail.
I have a typical phantom switch issue, but my attempts to fix it have not worked.

So, when the “2” target and “5” target switches are closed and the left slingshot is hit, it activates the collect bonus saucer. Whenever the “5” target and “6” target switches are closed, the left pop bumper fires. No other combination of switch closures on the target bank give me problems (i.e. 1-2, 1-3. 1-4. 2-1. 2-2. etc).

I removed J2 from the MPU and verified that this is not a board issue; no switches showed closed on the switch test.

I replaced the diodes on the 2, 5, and left slingshot switches with no resolution.

I replaced U10 on the MPU with no resolution.

I replaced all remaining diodes on the target bank with no resolution.

Where should I go from here?

Thanks.

Hi all. Sorry for the delay; work and home life have kept me pretty busy. I forgot to get pictures while I was down there today but I do have one from the other day that likely isn’t helpful to determine wether the spacer is appropriately positioned.

However, I think this is likely the cause. When I first started to diagnose this issue, whenever I tested the diode in circuit, it would give me voltage with my leads on either side of the banded side of the diode AND when the leads were reversed, to the order of 0.02 - 0.03 volts. If I clipped a leg of the diode off the switch, I get the expected 0.4-0.6 voltage drop with common lead on the banded side and no reading with the leads reversed.

Even more interesting is that this issue is totally intermittent. You can play 1 or 2 games with no issues, then on the 3rd every single time this scenario comes up and hit the left sling you get what are basically little jackpots. In some cases after this happens, the MPU gets lost, either adding balls to the game (game will go to ball 4 after ball 3 even though it’s set for 3 ball) or activating the left star rollover a bunch of times. I also found today they may having the 6 and 7 targets down followed by a left sling causes both the left and right pop bumpers to fire, and 5-7 causes only the left pop bumper to fire.

There are also no caps on the drop target switches 1-7.

I will get close up photos tomorrow. This is the only one I have on me. Top of photo is switch for #7 target.
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I’m sick of looking at the thing

Reporting back! I’m fairly certain I’ve spotted the issue. While taking pictures of the switch stacks to post here, I noticed a shiiiiiny little piece of solder splash on the “5” switch that (SO HELP ME GOD) I have missed the past 5 or 6 times I’ve been in this game. Unscrewed the switch from the bracket, cleaned it out with a dental pick, reassembled and played several games without issue. I’ll report back if it recurs.

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