If anyone that has a DH would check in their switch edges test and pull the trigger. This is switch 11 on the matrix. When I pull mine it also activates switch 12 on the matrix but there is no switch associated with this on DH. I get the little dot all the way to the left on row 2 when switch 11 is activate. This happens even when I pull the J207 and J209 and short the 1 pins together so playfield is eliminated. Just want to see if anyone else's activates the dot on row 2 so I can eliminate other issues.

The issue I am having is I keep getting switch 44 gun chamber switch credit dot. This switch checks out in the test. In game when the gun is loaded to start multiball it rotates slowly as it should. When I pull the trigger it starts rotating fast and the ball never gets shot out. I have logic probed the circuits for switch 44 and swapped in a new ULN2803 bu no changes. That is when I noticed the issue with the switch 12 being activated by the trigger button. I socketed and installed an LM339 at U18. No changes.

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u20 pin 1 and U14 pin 9 logic probe lights both red and green solid with yellow pulsing. The other side of U20 probes out correct.

I have not heard of pulsing at 50% duty cycle. Is this a bad thing?

An update to where I am so far:

When loading the gun to start multiball the gun rotates as normal. When I pull the trigger the gun rotates fast and either fires the ball in a random spot or does not fire the ball at all. I'm getting an error Switch 44 gun chamber now working. However the opto works fine in switch edge test. However when I check the trigger which is switch 11 not only does the dmd indicate it working but it shows a dot to the left or row 2. Since switch 12 does not exist I suspected this meant it is triggering switch 12 when switch 11 is triggered. I put the CPU in another game that has a switch 11 and 12. When I trigger switch 11 switch 12 indicates being triggered at the same time. I put the CPU back in DH and pulled the connectors from the column and rows at J207 and J209 and shorted pins 1 on each to trigger Switch 11. Same result as it triggers switch 12 at the same time. I've logic probed up the board and it seems to be fine. I replaced U20, replaced and socketed U14 and U 18. No changes. Hoping to get some insight to get this resolved. What am I missing?

No acid damage. Board is clean.

Shows open at the pins and diodes. U18 9 and 11 are 4k ohms, U18 13 and 14 are 20K ohms. Checked this on a known working CPU board and got exact same readings.

It is off the board. No damage that I can see and I've looked through my giant magnifying glass . Also no apparent damage to battery board.

U20 socketed from the factory. Put in a new 2803 already. 2k ohms on pins 17 and 18. This checks out on my known working board as well. I did socket and replace the U14 74LS374 earlier. 138K ohms at pins 6 and 9 on U14.

Using Terryb's logic probe guide post 12:
https://pinside.com/pinball/forum/topic/terrybs-guide-to-logic-probes

Everything probes out as it should. However where is point E at U13? I don't see an indicator for this output on the schematics or on the WPC MPU layout image at pinwiki.

Checked all resistors and diodes on these paths. All are within spec. Removed diodes and tested at 0.546.
Again checked continuity at U18-9 and 11, R53 and R54, D3 and D4, R29 and R30.
Checked continuity at U13-11 and 13 and got 138K ohms. On known good board I read 156k. I'm going to order a 74LS240 and replace on the off chance this is the issue.
Alos I removed and reseated the ASIC, U22, U4 and U6. No Changes. 4.96V at 5V cap and 11.91 V at 12V test point.

Problem was much simpler than I realized. Broken wire where the opto and coil wire come through the play fired for the gun and were shorting to each other intermittently. Caused the matrix confusion and also why the coil would not fire. Problem solved.