(Topic ID: 349356)

Bally 35 MPU Flash Gordon stuck on 2 or 4 ball games no matter dips

By slghokie

6 months ago


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  • 36 posts
  • 6 Pinsiders participating
  • Latest reply 6 months ago by slghokie
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#1 6 months ago

Have a Bally 35 MPU Flash Gordon that works/boots and originally was set for 3 ball and played 3 ball. After chasing some display issues (thank you to Quench), and updating roms to get freeplay, I now cannot get it to set on 3 ball play anymore. New 6810, 5101.

No matter what I set on dips 32 and 31 it either plays 2 ball or 4 ball games only. I checked all the diodes for all the dips and they test find out of game (diode test). I checked the dip switches and they work, even contact cleaned 31 and 32. A4J2 is repinned and I have no switch errors. Tried to turn off/on any of the other dips that had continuity with dips 31 and 32 and no change. For the 6810 to store at startup for 4 ball (which is what it is on now), 32 would read on and 31 off.

Otherwise the game plays as it should just 4 ball games.

Any help or ideas of how else to troubleshoot would be appreciated.

#2 6 months ago

With both DIP switches 31 and 32 off, how much resistance are you measuring across each of these two DIP switches?

#3 6 months ago

Quench 32 is 98.4k and 31 is 96.3k both off position in game with connectors

Out of game 32 is 101.2 and 31 is 99.3

#4 6 months ago
Quoted from slghokie:

Out of game 32 is 101.2 and 31 is 99.3

Hmm, two boards I have here on the bench measure 1.3 mega-ohms in one direction and if I swap the meter leads I fail to get a resistance reading (total open circuit).

Can you post a couple of high res clear pictures of the MPU board, particularly around J2, J3, U10, U11 and each DIP switch block.

#5 6 months ago

It has to be the “32” dip switch circuit (based on the manual settings, it is the only way to get 2 or 4 ball.) That circuit is stuck on for some reason.

#6 6 months ago

Quench i checked again. 200k ohm setting on meter and readings were the same. One way gives a measure and other does not (with the leads). Here is a pic of the area. 2518-35 board

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#7 6 months ago
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#8 6 months ago

Measure across the dip leads themselves from the back of the board.

There might be corrosion inside the switches from moisture the dips aren't a sealed unit.

#9 6 months ago

Quench If I take the board out, measure from the back with meter on 20M ohms I get dip 32 1.23M ohm, dip 31 is 1.17M ohm. On 200k ohm setting I get dip 32 101.3 and dip 31 99.3

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#10 6 months ago
Quoted from slghokie:

Quench If I take the board out, measure from the back with meter on 20M ohms I get dip 32 1.23M ohm, dip 31 is 1.17M ohm. On 200k ohm setting I get dip 32 101.3 and dip 31 99.3

Somethings not right with your meter. The resistance across the switches is either around 1.2M ohms or about 100k ohms. Your meter scale setting should have no effect on the measured resistance, well nowhere in the difference you're seeing.
Anyway let's move on from this because the readings aren't indicating a shorted switch.
The board looks in too good a condition to be a corrosion issue, but that doesn't discount it as a possibility. I once had a very clean non-booting -35 MPU board that turned out to have some corrosion in the CPU socket - never would have picked it.

1) DIP switches 8, 16 and 24 are all on the same switch return signal as DIP switch 32. Are they also acting like they're stuck on too?
2) What's the chance you're running some modified Flash Gordon software designed with this behavior ???

@slochar, do you by chance already have any diag code written to display the state of the DIP switches? I've thought about doing it in the past but never got round to it.

#11 6 months ago

You could try putting the old roms back in.

#12 6 months ago
Quoted from Quench:

@slochar, do you by chance already have any diag code written to display the state of the DIP switches? I've thought about doing it in the past but never got round to it.

Long time ago but don't recall what it was in some game I definitely don't have anymore.

I think I even reread them if you changed while power was on but don't remember for sure.

#13 6 months ago
Quoted from slochar:

I think I even reread them if you changed while power was on but don't remember for sure.

Heh, the first long code project I did I added the ability to re-read the DIP switches in attract and game mode by pressing the MPU S33 switch.

Flash Gordon has enough display digits to show the state of every DIP switch simultaneously. I might look into it over the next few days if I have time.

@slghokie, I don't recommend it just yet because it's rather a virgin board but if you feel like gun shotting, desolder and remove that DIP switch 25-32 block to see what happens.

#14 6 months ago

Quench sounds like I may need a new meter battery or now have the excuse I need to get a Fluke

Dips 8, 16, 24, 32 are all set to off in current configuration. I can flip them all to on and see if it does anything different. I just put a dip bank in my Marco cart so can order one and have it on hand and can certainly desolder that 25 to 32 bank. I tested continuity on all them and they seem to function properly but I guess corrosion or stuff could make it work wonky if it is in there. As you say, this is the cleanest Bally board I have ever seen. Since they are matrixed then it could be phantom from another unrelated switch.

slochar I can put the original U2 and U6 back in and see what it does. I tried roms I burned and some I ordered out of CA. When I first got it the 3 ball worked. At some point it stopped as I was chasing other issues (display and bad 5101), and now no matter the rom I use it stays 2 ball or 4 ball.

Could this problem manifest only when the game is powered on and like a diode or cap is then failing to show 32 as on? All my testing has been with game off for continuity/resistance? I think the 6810 gets the read onetime of dip settings and refers to that from then on. Guess I can test with game on.

#15 6 months ago
Quoted from slghokie:

I think the 6810 gets the read onetime of dip settings and refers to that from then on.

That is 100% correct. The dips are read ONCE at bootup, right after the 7th flash, before the game plays the bootup tune, and then are just referenced from the ram.

Try starting the game up with J2/J3 disconnected - after it's booted, plug them back in (you won't hurt the board doing this) - see if it works then.

#16 6 months ago

I would touch up the solder joint on the left side of the board. It looks like it has a cracked joint on both ends of the component.. Probably not what is causing the problem though.

#17 6 months ago

So I tried what slochar suggested and booted with j2 and j3 disconnected, reconnected after boot. And it will consistently do 3 ball with 32 and 31 dips set to off. Boot with connectors on and it does 4 ball only.

#18 6 months ago

Try those connectors one at a time with same test. When it fouls again the one that is connected either cab or playfield has a switch error. Check the coin switches first they can cause lots of problems if stuck or shorted

#19 6 months ago

Tried with J3 disconnected until after boot and it does 4 ball. Also tried with coin door disconnected at startup then reconnected also 4 ball.

So J2, I think pin 15 connects to dip 32 so does that mean something on this part of switch matrix is driving it? Just odd I don't have any switch faults when I go into test.

So if I boot with the ball out of the outhole/trough then put it in it does a 3 ball game. So the diode on the outhole switch perhaps?

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#20 6 months ago
Quoted from slghokie:

So if I boot with the ball out of the outhole/trough then put it in it does a 3 ball game. So the diode on the outhole switch perhaps?

The outhole switch has fishpaper above the upper leaf to electrically isolate it from the wireform. Inspect it's there and hasn't slipped over the wireform lever.
The outhole metal parts are connected to ground via the apron and lockdown bar receiver and so it's critical the fishpaper is doing its job to isolate the switch from ground.

#21 6 months ago

So I checked if any of the blades were grounded and they did not seem to. I removed the outhole switch from playfield and closed at boot it does a 4 ball game. Open outhole switch removed from playfield at boot it does a 3 ball game. Removed from the playfield was just to rule out contact on the apron/ground. When that switch is in the game it only does 4 ball. I checked the fish paper and used electrical tape to isolate in game and it still did 4 ball

During all this the single drop target was down. I raised it up and tried again with outhole switch closed removed from playfield and it did 3 ball. So I will investigate the single drop next.

#22 6 months ago

Tested again this morning:

Outhole switch detached from playfield and closed + single drop open (not dropped) = 3 ball
Outhole switch detached from playfield and closed + single drop closed (dropped) = 4 ball

So that gets me around the outhole as the cause I believe.

Here is the pic of the single drop target. It has fish paper but in closed (dropped) position none of them conduct to ground or the drop assembly. Diode looks like it is touching metal but it is the angle of the shot, not touching. Does the diode need to go the other direction? All the other drops are up and should not have any other switches made so hoping the single drop is the end of the line on the matrix chasing.

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#23 6 months ago
Quoted from slghokie:

Outhole switch detached from playfield and closed + single drop closed (dropped) = 4 ball

Can you quickly check something, does it still happen if you put DIP switch 27 OFF on the MPU board?

Quoted from slghokie:

Here is the pic of the single drop target.

Hard to see how the switch is stacked in the picture but do you measure a short circuit across the diode?

#24 6 months ago

Quench the diode does not test shorted, tests as it should no measure one way and a measurement in diode test the other. I turned off dip 27, started game with outhole closed (still unscrewed from playfield) and single drop down and it did 3 ball!!! Holy Cow!!!

Also did it with outhole open and single drop open and BOOM...3 ball!

Looks like that is credit display on/off. Would love to know how that "fixes" it and if there is still a root cause to solve. But I can live with not seeing the credits since it is in freeplay.

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#25 6 months ago
Quoted from slghokie:

Looks like that is credit display on/off. Would love to know how that "fixes" it and if there is still a root cause to solve. But I can live with not seeing the credits since it is in freeplay.

It's because the same PIA's that stobe the switch matrix also strobe the dip switches (once for each set of 8, at bootup) - so anything amiss there can transfer over. It's likely a shorted diode on that line, they have a diode for each switch just like the regular matrix does.

#26 6 months ago
Quoted from slghokie:

Looks like that is credit display on/off. Would love to know how that "fixes" it and if there is still a root cause to solve.

The DIP switches are actually part of the overall switch matrix.
The fault is not DIP switch 27, nor the outhole switch. It's at the single drop target.
DIP switch 27 and the outhole switch help create the "box" shown below in green where a shorted switch diode creates a ghosted closed switch in the opposite corner of the box.
When the U10 CB2 signal activates the strobe #8 on that DIP switch block 25-32, it is getting a ghosted active response on the I7 switch return line where DIP switch 32 lives on via the switches shown as closed with the fault at the single drop target switch.

For whatever reason the diode at the drop target switch is not blocking current flow.
What happens when you measure the drop target switch diode when that switch is closed?

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#27 6 months ago

Looking at that drop target switch it looks like the resting/tension blade is poorly positioned such that when the switch is closed it is possibly shorting the return line to the strobe line essentially bypassing the diode.

#28 6 months ago

Hmm -- Quench slochar Could this be something I need to dig into on that Xenon I posted about in the Xenon club thread that was doing this across multiple Alltek boards? Not to hijack the thread here but what switch could be doing that on Xenon? I do need to go replace a broken drop target on that game sometime this month.

#29 6 months ago

When I measure the single drop diode closed it tests the same as open (nothing one way and reading the other).

That diagram with the DIPS is AMAZINGLY useful!!!

So I adjusted the resting blade on the switch and it does not touch open or closed. I put dip 27 back on, outhole still detached, closed and single drop down (switch closed) and it does 4 ball. Then I just replaced the diode and it still does the same. So does that mean something else in the green box area has a bad diode?
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I also checked the fishpaper on the single drop and it is not conducting to the drop target arm it rests against with the fishpaper in the way.

#30 6 months ago
Quoted from slghokie:

When I measure the single drop diode closed it tests the same as open (nothing one way and reading the other).

Ugh, of course it does. It's because the switch is wired wrong and the diode isn't even in the circuit...
The diode needs to be swapped around so the banded diode leg is on the side switch lug. The white-red strobe wires then need to be on the end switch lug where the non-banded diode leg will now be.

#31 6 months ago
Quoted from play_pinball:

Hmm -- Quench slochar Could this be something I need to dig into on that Xenon I posted about in the Xenon club thread that was doing this across multiple Alltek boards?

Well looking back at your Xenon issue, it does sound very similar but in my post #2206 response I was very specific in stating that DIP switch setting changes can't be recognised until a reboot occurs. You said it changed from 3-ball to 4-ball after a few games without a reboot which made your situation weird. If that was a mistake you could be looking at the same issue as here, not necessarily on the same playfield switch number. If so when it's booting into 4-ball mode find which of DIP switch 25-31 are helping to cause the issue, and then look back at the playfield switches on the same offending DIP switch return line.

#32 6 months ago

The diode needs to be swapped around so the banded diode leg is on the side switch lug. The white-red strobe wires then need to be on the end switch lug where the non-banded diode leg will now be.

I know this is a really crude drawing but is this what you mean?

Diode path stay the same just the band changes...I know in the crude drawing it looks like it overlaps with the red/white but intent is move the lug on the white red

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#33 6 months ago

Quench well I was excited so I went ahead and wired it that way and no matter what outhole or single drop do...IT IS ON 3 BALL!!!!!!! (dip 27 on)

Thank you Quench and slochar for helping to solve this and diagnose the true cause. Now I understand the matrix alot better and see how it can cause havoc but at the same time be traceable and solvable.

I like to dub them electronically good before I do the playfield, rubbers, LED's, and such. So now I can do those with FG. Thank you again as it is a grail machine for me. Also, now it is electronically good.... I can finally put the backglass in and have the full experience.

#34 6 months ago

Well, freeplay and balls per game (3) are right but the run away scoring now happens on the single drop target. I checked the switch to make sure fish paper and tension are all good and cannot see anything off on it. Sometimes it scores right 10k and sometimes it just goes and goes.

#35 6 months ago
Quoted from slghokie:but the run away scoring now happens on the single drop target.

Glad to hear your initial problem is fixed.

Just want to make it clear, this run away scoring has nothing to do with the diode on that switch.
You're likely looking at a mechanical issue with the switch. Contacts need another round of cleaning. Oddly the game doesn't software track/remember when that target is knocked down to prevent intermittent contact causing rescores.

#36 6 months ago

Quench agree. I messed with it last night and can get it to act properly. Eventually need a full clean and rebuild but flipping for now!!

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