There's an incandescent 555 bulb in a socket near the solenoid expander. There isn't an LED in there, by any chance? It's important a regular incandescent 555 is used in that socket in order for the solenoid expander to work properly.

If you put the game into lamp test using the button on the inside of the coin door, the relay on the solenoid expander should start clicking at a regular interval and the lamp next to it should flash in unison. Does it do that? With the coin door open, you should be able to watch that lamp (saving you the trouble of opening up the playfield if it's currently down)

Yeah, sounds like you might have a couple different things going on. Could you post a few pics of the boards in the backbox? I would like to see what kind of boards are in there and what condition they appear to be in. Also, try resetting all the drop targets and remove the ball from the game, then put the game in switch test and test each switch to see if it's associated number comes up on the displays. Here's the chart from the manual that shows which numbers correspond with each switch. While you're at it, you should also confirm the correct coils/solenoids are firing during the solenoid test--the chart also tells you which ones should fire at each step of the test.

Screenshot_20210228_142808_com.google.android.apps.docs(1).jpg

You're welcome!

The boards all look original, and they appear to be in decent shape. I'm not seeing much, if any battery corrosion on the mpu board (the one inside the backbox on the left). It looks like the board on the right inside the backbox (the Solenoid Driver Unit aka SDU) is due for a couple upgrades, looks like original capacitors on it. That board supplies the power to the mpu and the other circuit boards, and if it's worn out it can cause problems. Do you have a multimeter? I always recommend starting off by measuring voltages at that board and also tracking down all the fuses in the game to verify that they are good and properly rated for their circuits. This is all stuff i can help guide you through if you like.

Btw, i don't think the video went through. Could you try posting it again?

Actually, on closer inspection it does look like there may be some battery leakage on the mpu (the board on the left inside the backbox). Could you take a couple closer pics of the bottom region of that board?

Here's what caught my attention on the MPU. Note the discoloration around the chip. Do you see that around the other components along the bottom 1/3rd of the board?

Screenshot_20210228_155951_org.mozilla.fennec_fdroid(1).jpg

I'll tell you right now, the mpu is gonna need some work. The battery that leaked on the board got removed at some point but the damage is done unfortunately.

Good news is a replacement mpu is not terribly expensive and there are good aftermarket choices available these days. Replacing it will likely fix at least some of the issues you're having. I'm a fix-it type so I'd try to fix the board if it were my own game, but in this case you're probably better off going with a new replacement.

Don't worry about the video for the meantime!

Here's a link to the mpu board i would recommend: https://nvram.weebly.com/new-pcbs.html

The first one at the top of the page is the one for your game (you'll just need to specify it's for a Mr&Mrs Pac if you order one). It's listed as: NEW UNIVERSAL Bally / Stern MPU (-17, -35, MPU-100, and MPU-200)​
$160 + $7 shipping

They also offer other replacement boards if you should need any others for your game. Very good quality replacements, and very fair pricing too.

It still wouldn't hurt to make sure you have good voltages at the mpu. Here's where you want to put the probes:

Red lead on test point 5 (circled in red), black lead on test point 4 (circled in black).

1581040958.png

You want to set your meter for dc volts (20v range), the top green arrow in the pic. Also, the black probe needs to be plugged into the bottom port on the meter, as other arrow is indicating:

1648082802.png

Hmm. We're supposed to have approximately 5 volts DC with the meter probes on those points. Did you test it with the game powered on?

Let's try the switch test again. If you reset the drop targets and remove the ball then put the game in switch test, does the display show "0" indicating no switches are closed? If it's not showing 0, what is it displaying?

If it shows 0 as it should, put the ball in the outhole and see what number it displays.

Does the number go away if you take the ball back out?

Also, just to be sure: are the drop targets all in the up position?

Lift the drop targets up with a flat screwdriver or something. You should be able to raise them manually so they'll stay up. We basically want all the switches on the playfield deactivated before going into switch test. With no switches active, it should read 0. But if it was reading 0 with those drop targets down, then it would appear there's a switch problem.

Also, try unplugging the top right connector for the mpu board and plug it back in. Make sure to line the connector up properly when putting it back on.

You're welcome, lol!

Sounds like you may have a broken off wire or diode on one of the switches under the playfield and/or connector issues at the mpu. Have you spent much time under the playfield yet?

Also, you said the switches are reporting the correct numbers except the 4 drop targets? I'll have to get another look at the schematic later and see what else i can come up with. When you say the ball is in the ball return, where exactly are you speaking of? Post pics if that's easier.

Well, let's take a crash course in reading the switch chart. I think i already see a common thread here, but we'll get to that in a minute. There's numerous switch charts in the manual, I'll post 3 of them for easy reference. First, here's the numbered chart for reference to the switch test.
Screenshot_20210301_172348_com.google.android.apps.docs(1).jpg

In this next chart, the positions of each of those switches is shown. Note the switches are the numbers with the circles around them. Using the numbered chart above, you can match up the position of each of the switches on the playfield on the chart below. For instance, the "ball return" you mentioned is called the "Outhole Kicker", and it's at switch 05 at the bottom of the playfield:
2035836900.png

So now you see how to match up the switch numbers you see in the test with the positions of each of the switches on the playfield. Note that the above chart also shows where the solenoids/coils are on the playfield, but their numbers are in boxes instead of circles.

The next chart is gonna get a little more complicated, but is arguably the most important one to get familiar with. This is the switch matrix diagram from the schematic:
Screenshot_20210301_172627_com.google.android.apps.docs(1).jpg

The switch matrix is a very clever way the engineers were able to use a much smaller physical footprint (and *way* less wiring) to read as many as 40+ switches on any game. Basically the cpu "scans" each vertical column of switches in quick succession (checks the 1st vertical line, then the 2nd one, then the 3rd, 4th, 5th, 6th, back to 1st...over and over). Any switches that are closed (activated) when their column is "scanned" by the cpu get registered by the cpu and proceed to score points, bump bumpers, or whatever the switches function may be. The cpu continuously scans each column of switches in succession at a very fast pace (60x per second?) allowing it to pretty much "see" all the switches at once and react to any of them in a fraction of a second. (I'm greatly oversimplifying, but i believe that's the gist of it)

That said, take a look at the first vertical column of switches it will scan: starting at the top-left and working down we see "Left 4 Drop Target 1(bottom)", next one down is "Left 4 Drop Target 2", "Left 4 drop target 3", "Left 4 Drop Target 4", "Outhole", an empty/unused spot, "Top Left Saucer", and "Right Saucer". Any of these ring a bell?

Basically, all of those switches i just listed from the first vertical column share a circuit. If you take a close look at each of those switches under the playfield, you'll notice they all have wires of the same color as the other switches in that same vertical column of the chart.

Take a look at the outhole switch and locate the white-red wire (white wire with red stripe) on that switch. Then locate the saucers listed in that same vertical column on the switch matrix chart and find the white-red wires at those switches. If you're having trouble figuring out where they are on the playfield, the 2 other charts should help fill in the blanks.Then locate the white-red wire(s) at the left drop target bank. Do they all appear to be attached to their switches, or do you see any broken off? You can gently tug on each wire to make sure they're firmly connected. In fact, send pics of each of the switches and wiring to them. I'm starting to suspect we may find a fault under the playfield that could explain why your switch test is showing 0 when you put the ball in the Outhole and why the drop targets aren't registering. Consulting the switch matrix chart, those are all on the same column: left drop target switches, outhole switch and saucer switches. The reason it's important to check the wiring and diode at *all* of them--and that includes those saucers even if they work in switch test--is because a break anywhere in that circuit can cause some (or all) of the other switches on the same circuit to also stop working.

Another important thing: each switch has a diode attached to it. Here's a pic of a typical switch and diode: 68243588.png

It's important that the diode and wiring to the switch are correctly oriented. Note the diode has a band at one end of it's body. It is there to denote the orientation of the diode (it's important to put the banded side on the correct switch lug or it will cause problems)...For now, make sure each switch you inspect under the playfield has a diode attached firmly at both ends.

Something as simple as a broken-off diode leg or wire from any of the switches solder lugs can cause all the other switches on the same vertical column (or horizontal row!) to stop working. There's other things that can cause issues for a group of switches to stop working, but those would be the first things to get a close look at. Make sure the solder lugs on the switches aren't mashed together or contacting anything adjacent (other switches, lamps, anything metal) and that the diode isn't touching anything adjacent either.

For now, take some time to familiarize yourself with the above charts and try to make the connections looking at the wiring and switches under playfield. I intentionally left out certain info that will be pertinent later (how you determine wire colors and some other stuff)... i don't want to overload you any more than necessary, lol! I realize this is a lot of info to digest, so be sure to ask any questions you have. I did my best to keep it as simple as possible. Once you get the concepts, it makes a lot more sense.

No prob! Like i said, there's a lot to digest here but in time it will all hopefully click.

I will say, pinball has been one of the most fun and rewarding hobbies I've found. I've also met some unbelievably helpful and knowledgeable folks along the way. If you're ready to take the plunge in earnest, you're in the right place!

One way or the other we'll get this thing working!

I was hoping the board would be the solution!!! Woo hooooo!!!! That's terrific news! You don't owe me a penny, it's been my pleasure to help out a newcomer. Just paying forward for all the help others have provided me for the same price

What a thrill to get it working though, right?! That's really what I'm in it for. That feeling is so awesome when you finally get it working and get to play it!!!

Sooner or later issues will arise but just know there's a whole group of master techs here that will help if you give them time and follow their instructions carefully.

Always feel free to hit me up on this thread or via pm if you have any questions moving forward, or start a new thread if new issues should arise.

Now enjoy your game!!! Congrats!

Btw, i think i may see an error with the wiring on those left outlane and inlane switches. Could you take an even closer pic of them? I think the diode is reversed on both of them, which *may* cause some strange switch behavior. I actually just fixed a problem on my Eight Ball Deluxe (same vintage and brand as your game, same funky cabinet for that matter!)... The reversed diode caused some very strange issues, and they were all corrected by orienting the diode correctly. See in the first pic how the banded side of the diode is on the same solder lug as the wiring? Normally the diode should be flipped around, the non banded side should be on the lug with the wiring, and the banded side should be soldered to the other lug. The arrows i added are pointing at the banded side of the diodes. I also pointed out the amber residue left by previous soldering. Anytime you see that stuff, you can presume someone took that wiring/mechanism apart at some point. Doesn't mean to suspect bad work, but don't necessarily expect good work either. The reversal of the diode may not even cause any noticable problems, but i thought it was worth pointing out. It just doesn't look right to me, and I'm not sure how/if it would manifest as a problem in this case.
1636161891.png

Notice on this next pic, the right side inlane and outlane switches, that the diode is oriented differently--the wiring is going to the non-banded side, which is correct. There's also no flux residue, so it appears the solder connections there are factory, untouched since (and thus are *presumably* correct in wiring and diode orientation).
985910799.png

So again, judging by the presence of leftover flux residue on the switches with the seemingly incorrect wiring, I'd say someone took apart or replaced those switches at some point and put them back together with the diodes on backwards. If anyone else is following, could i get a second opinion on this?

Well, I'm still thinking the diodes look reversed. Have you noticed any irregular scoring or behavior since getting the game running? If it's not affecting anything, you may just want to hold off doing anything with them yet.

I'd put the game in switch test and verify all switches are registering properly. Remove the ball, make sure drop targets are up, and test each switch on the playfield. Verify the correct number comes up on the displays for each switch you test. If everything checks out and you don't have any issues in gameplay, I'd say you're good to go for now!

That's great to hear it's been working well!

It's possible the weaker pop bumper needs to be rebuilt--could be a broken piece or 2 causing some slop in it's movement. It's also possible it had been taken apart in the past and reassembled incorrectly or with a wrong part. Could be other things too, but that's where I'd probably start looking.

Do you mean that when the ball goes out of play it sometimes takes a little while before it registers that it's out of play?

Just curious: have you managed to plunge the skill shot yet? It's such a difficult one to make!

frunch First, this was not my thread but it was immensely helpful, especially understanding the switch matrix. I have this machine, in very bad shape. I picked it up from a friend back around 2003 when he was moving and didn't have a place for it. I think I paid him $300. It mostly worked but the playfield is in really bad shape. Was a great treat for my kids. Come 2014 I moved across country and despite the complaints from my wife, this was broken down and loaded on the moving truck

Sadly, it sat for about 8 years now in my garage still apart. My plan was to move everything to a playfield I have that is in better shape, not great but at least 95% of the paint is still on it. I finally put the thing back together yesterday and to my surprise, it powered up and would play... for one ball. With the help of this thread I found a bunch of stuck switches.

It's still flaky and I know I have something shorted maybe somewhere as sometimes it wont power up or flakes out. My player 1 score flickers just like the OP too. Trying to decide if I put the time into restore this or sell it off whole or for parts. Either way, thanks again for all the input to this thread.

That's awesome, I'm glad my post was helpful!! Congrats on getting your game up and running again!

Let us know if you need any further help.

Hi @frunch, this is a super helpful chat. I’m having similar issues with a MMP machine and have replaced the MPU, solenoid board, sound board, and the aux board. The game has come back from the dead but the bumpers and slingshots work intermittently. Also, the skill shot often does not work and the ball just gets stuck. However, other times everything works great. I’ve run the solenoid tests and everything seems to work great during testing. It’s just during game play that things start to fail. Any ideas or suggestions on what to try would be much appreciated. Thank you!

Glad my posts were helpful!

Sounds like it's probably an issue with the switch matrix on your game--that could explain why the coils work consistently in the coil test but only fire occasionally when activated in response to switch closures during gameplay. I see you have replaced the MPU, but have you re-pinned any of the female connectors that plug into it? The connector for the playfield switches is at J2 on the MPU (I think it's the upper connector on the right side of the board)... Connector problems are *super* common on these games, so hopefully that's what we'll find here...