I just got the game up and running a couple days ago, '78 playboy, and was playing fine. Last night a tilt issue arouse, when you push the start button, it does the start up music, resets the drop targets, does not kick the ball out of the out-hole and immediately lights up tilt. Like I said it was playing fine for the last two days, in switch test no switches are showing stuck on. In all the other examples I could find online with this issue normally the switch test would show something then leading you to suspect diode or the capacitor on the plumb bob tilt. In switch test if I manually close each tilt switch they register as closed so they appear to be working. Any suggestions to likely culprit? Thank you in advance for guidance.

Just tried that and no change.

Bingo. Kicked the ball out manually then pushed start botton, game started and fired out hole coil. Then as soon as ball drained and pushed down the out hole switch tilt happened. So what is the cause of this and what do I need to do to remedy it? Thanks so much again.

I did not do any tinkering with it. Just been playing it since finishing it Friday. No phantom switches that I've noticed during game play. Had been working and acting normal until this error. I have some 1n4004 diodes I'll just replace that one on the out hole switch and see if that fixes it. There were just couple capacitors I didn't replace on a couple targets bc they were still in tact but new capacitors everywhere else under playfield that had the old ones cut out at some point. I'll report back once I address that one diode and know results. Thanks

okay, I changed out the diode on the kick out and no change. Found if i manually separate the leaf switch on the kick out it fires the coil and pushes the ball to the shooter lane. Used ohm meter and checked the other diodes in the matrix with the kick out they appeared to be okay. I went around and manually triggered things in the play field and found that if I push the top right pop bumper it does not fire but it causes the top left to fire instead. Everything else in the play field is working accordingly. Looked underneath and didn't find anything shorting or touching where it shouldn't. The top right bumper and bottom bumper both have the old capacitors, top left was missing one so I put a new one on it. Could it just be the capacitor causing that effect? Also I am confused, if I use my ohm meter to check a diode out of circuit, putting black lead on the diode side with the strip and the red lead on the opposite I get a reading of roughly 600 (1N4004), my meter doesn't give a decimal reading. Now if I check a diode on a coil in circuit, leads on same sides as stated of diode, my ohm meter buzzes like its a short, is that normal? Its doing that on all the coils. Checking the diodes on switches I get the roughly 600 reading and no buzz.

They activate in the correct order during solenoid test. However in switch test top right and left bumper register #39 which is the assigned number for the right bumper. Get #39 also when just depressing the left bumper.

I clipped the capacitor from the right one and no change, the left has a new one on it. Bottom one is an old one. I didn't try removing the other two yet.

I started a game, then removed J3 from mpu, the ball did kick out when I did that, but after the ball went back into the out hole tilt came back up and it would not kick the ball back out to the shooter lane. (one time after the ball went back into the outhole with J3 disconnected it did kick the ball back out to shooter lane, but only once)

checked that with ohm meter in continuity to make sure none of the tilts were "activated". Diodes on the tilts also checked okay with ohm meter.

I replaced all lights to LEDs, with the led adapter on the lamp board, but they were all in place Friday when I finished the game. Maybe something shifting with game play. How did you go about finding that problem bulb?

This just seems to get worse.
Took out F1 fuse real quick that did not fix the problem.
Wasn't fully sure what I was suppose to do for measuring the resistance of the wire on the switch for those lanes. I put the meter on 200ohm, and put one lead on the orange wire at the switch and the other lead on the other end of the wire at the MPU, meter read 0.5. I got the same reading doing the same thing for the brown-white wire.
Did the switch test and went through all the switches and there is more then one problem child apparently.
Switch / Registered / Assigned Number
Outhole 7 / 8
Slam 2 (on coin door) 15 / 16
Flipper Lane (L and R) 23 / 24
Grotto 31 / 32
Left bumper 39 / 40

Left bumper fires when the right bumper switch is closed, and the right bumper does not fire.

And again all the coils during solenoid test fire and fire in the correct sequence.
Page 21 for switch assembly self test
http://mirror2.ipdb.org/files/1823/Bally_1978_Playboy_Manual.pdf

I just ended up disconnected at least one leg of every capacitor. The three bumpers, 5 stand up targets, 5th key stand up target. No change to the issue.

Diode was not touching the door. I did notice that some solder from the one leaf was touching the bracket that hold the switch in place, cleaned that up but no change.

Just un-soldered the wires to those and still no change.
When I removed the one switch it did start the game and kick the ball out to shooter lane but then when ball went back to out hole it tilted. And further attempts to start a game failed with the ball not kicking out and an immediate tilt.

When I put the meter on those two wires at the role over switch I get no reading. You do mean to put a lead on each wore that is plastic covered in picture correct?
(MPU has all new header pins and I did check with ohm meter when I did them to assure no bridges betweens pins)

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Okay so I booted up the game did your test and the game worked normal, all switches operating normal, the right pop bumper working normal, flipper lanes scored appropriately (not adding the additional 1000 points). Test it for a couple games. Then decided to try and actually play, when I lost the ball in play it tilted and from there on out all problems back. So starting a game with the ball out of outhole, I manually racked up a bunch of points on the bonus, the ball immediately tilts entering out hole. The game silently processed the bonus's but did not add the score to the display, just did the cycle of lights around the bonus, proceeded to reset the drop targets then stop there. again if i manually separate the out hole switch the ball gets kicked out.

The tilt pendulum, ball tilt, and playfield tilt all register 7
Left Out lane registers 23 (so do the flipper return lanes)
5000 arrow registers 31 (so does grotto switch)

With the connector removed the door slam and the slam next to the pendulum both register 15.

Below is the post I started when I acquired the game, you can see what the board looked like when I got it. My first board repair/revival, but looking like it still has issues. The discolored solder on the components yet was caused from the toilet bowl acid I used to get the corrosion off. I'll post a couple more pics of the board all done with the components replaced.
https://pinside.com/pinball/forum/topic/bally-playboy-mpu-repairable#post-3539539
U10/11 were resocketed and chips are original ( I have replacements on hand)
U8 resocketed and chip replaced
U14 replaced
U9 Original socket and chip (I have the items on hand resocket it and I have replacement chips for U9)
Did the battery acid damage kit from great plains, and did several other components beyond that kit that were not included.
I did not replace the dip switches but have them on hand if deemed needed to replace
When I finished the chips that I did resocket or replace I did check for continuity to the next component from each leg. All new header pins and all wires have new crimp terminals.

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the only cap that is still connected (forgot about that one last night when I removed all the ones from under the playfield) is on the plum bob tilt, I'll clip that and try again.

Just went and clipped that last capacitor. And no cigar, immediate tilt atgame start.

Turned off the the dip switches. Booted the game without the ball in the out hole. Went into switch test. Everything worked normal and switches numbered correctly. Turned game off, put ball in outhole, rebooted tried to start a game, immediate tilt and all associated issues stated before back. Turned game off, removed ball, rebooted, went to switch test and all issues present, miss numbered switches and the pop number issue. Yesterday it worked 100% normal for a couple minutes when I was testing your suggestions but then it reverted to its issues. Tonight or tomorrow at latest I can pull out MPU and swap out u10/11 with diff chips and try that. Could the old socket on U9 cause any of this? Not sure what functions U9 services. Thanks again for all the guidance.

I'll try to fill those voids in you pointed out. Any tips for getting the solder to stick on the top side. When I tried before it would stick on the top side and would keep flowing to the backside of the board creating a large solder bludge I'd have to clean up. I did check continuity from each component when I did the work, to the next component. The solder around the dip switches got discolored when I used the toilet bowl acid method for removing the corrosion. That picture is deceiving and makes it look like corrosion.

In your opinion would it be better for me to remove that dip switch, do any cleaning that is needed and install a new one then proceed with the tests you mentioned. Or do your test first?

Okay. I'll be able to do those test this afternoon and will report back.

Okay have the measurements and clearly a set from each one area are off. It also took the game 3-5 min before it finally started its issues after I booted it up.
Meter set at 200kohm
In the order of your request:
A: j3 16&15. 4.0
B: j3 13&12. 103.1
C: j3 11&10. 103.7
D: u10 17&16 1.1-1.4 (fluxuated a lot)
E: u10 14&13 100.1
F: u10 11&10. 102.7

I will have that dip switch taken care of by the end of the weekend likely.
For my understanding: could the short be in the PIA itself or only possible short externally? If it is the chip itself swapping the two around would allow U10 to work correctly but then would there be issues elsewhere since U11 had what may be a bad PIA? Would it be better to swap U10 with a replacement chip instead of swapping? I have 3 spares if I recall. Just trying to fully grasp all this. Thank you so much again. Will report back once the solder work is done and the board is back in the game.

As requested here are some photos of the main suspect dip switch. Underneath it was more like a film that cleaned up, I'm guessing from the acid towlet bowl cleaner and the distilled water didn't rinse it all out.
Out of curiosity can you use the ohm meter to check each dip switch. No idea what I am doing but for the heck of it put meter on 200k ohm and tested each switch on that one and on several I got a reading. Tried it on the new one and I get 0. If anything I did was correct does that suggest the issue may have been within the dip switch?
Getting ready to desolder the next one...

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I am getting 114.9 now at pins 17&16 with the PIA out currently. Still have two more dips to remove.