(Topic ID: 157509)

Bally Speakeasy Lamp and MPU Issues

By mtgedney

5 years ago

Topic Heartbeat

Topic Stats

  • 40 posts
  • 6 Pinsiders participating
  • Latest reply 5 years ago by Quench
  • Topic is favorited by 1 Pinsider


Linked Games

Topic Gallery

View topic image gallery


#1 5 years ago

Hey everyone! Still working on bringing this pin back to life and it hasn't been easy. Yesterday I was just doing some final adjustments with the flyaway targets and various other minor playfield issues. All of a sudden after working on this thing for about three weeks, Adding coins was troublesome. Reflowed solder over the connectors and that seemed to resolve it. Today I lost nearly all lamp with exception of the GI. Three lamps stay on all the time, even in test mode. Coin mechs are doing the same thing whereby all three coin switches do not register. I jumpered directly from the board pins to the coins switches giving the same results. All test points giving proper results. Is the MPU on the fritz? Any ideas? Seem unrelated but happened at same time.


#2 5 years ago

I took out most of the controlled lamps by blowing 2 of 3 playfield fuses when replacing bulbs with game in attract mode. Not sure if this could be part of your problem?

#3 5 years ago

Playfield fuses are good.

#4 5 years ago

It sure sounds like mpu issues, can you confirm the board is completely booted?

The gi is always on so we can ignore that. The 3 lamps locked on looks like a non-boot. Are you getting the right number of flashes on the mpu? Are the displays working? I'm assuming they are since you can get to lamp test.

The display driver board completes the path to ground for the lamps. By grounding the tabs of the scrs on the LDB while in lamp test mode the lamp should light. If this works it is clearly a mpu (or wiring) issue. How do the pins look? Shiny or dull? Same with the crimp ends in the connector.

#5 5 years ago

Are any switches registering in the switch test mode?

If you disconnect both J2 (harness to playfield switches) and J3 (cabinet switches) off the MPU board, do the 3 spinner lamps still stay on?

Both the switches and lamps share mostly the same control signals from U10 (6821 PIA) on the MPU board which could explain why both are playing up at the same time.
You could try swapping U10 and U11 since they're both 6821 PIA's. If your PIA in U10 is faulty, it will cause display issues if it's plugged into U11.

#6 5 years ago

I am getting correct flashes on MPU. Also, I swapped pia chips at u11 and u10, no change in its behavior. It could be connectors, but I doubt as I have attempted to jumper directly with no avail. I also reflowed pins. If I had another good MPU I'd give it a go. Do the scrs work like a transistor?

#7 5 years ago

The scrs are similar but are measured differently. Pinwiki talks about the differences. Being able to ground the tab (or the metal back) works the same though.

I had a stern nine ball that would only fire the bank reset and outhole solenoids and it did it every 10 seconds. It was a connector issue.

#8 5 years ago

On my Speakeasy, when I accidentally shorted a couple connections on the flyaway target board, I blew out something... can't remember what (maybe u10 and 11?) that caused all sorts of issues like the one you have. In your pic, it looks like it's possible there might be a short there. You did say you were working on them.

#9 5 years ago

I actually was working on the flyaway targets. That's when things went downhill.

#10 5 years ago

Did you try to disconnecting both J2 and J3 (switch harnesses) off the MPU board? This might confirm that you have a short in your switch wiring (which it appears you have).
Do you have a pic showing your flyaway targets pointing to what you were doing with them?

#11 5 years ago

Pulling j2 or j3 on the MPU does not change symptoms.

#12 5 years ago

I presume the displays are working ok?
Have you got a logic probe or other means of checking signals on the MPU board?

#13 5 years ago

Oh, in the mean time, are any switches responding in the switch test? If yes which ones?
Also if you completely disconnect the Lamp driver board, do the coin switches then respond?
Just trying to isolate if the issue is wiring or not.

#14 5 years ago

Displays function. I don't have a logic probe. My only resource is a DMM at the moment. Most switches register as closed if I close during switch test. A handful along the right side are not working. It would come at no surprise that I cannot close any of the coin "in" buttons. Credit reset functions. Occasionally, the right saucer will say it is closed when it clearly is not.

Another point of note is that when this happened, I lost a few lights that scroll in attract mode in the back box that I believe are driven by the aux light board. This again points to problems on the MPU, or at minimum connectors from that source. I think I will order me some fresh .100 and .156 connectors and start there. I appreciate all of your comments and suggestions. Keep them coming no matter how simple or obvious. Often times its the simple things that get over looked in these cases.

#15 5 years ago

1. I see in your first pic there's been some solder work on the PCB above the flyaway targets. Is that what you were working on when things started going wrong? Have you checked for shorts in the soldering?

2. What are the handful of switches that aren't working on the playfield? This will help to better understand all signal lines that are playing up in the switch matrix.

3. Do those 3 spinner lamps come on immediately when you power on the machine?

4. With the machine OFF and your DMM set to read low resistance, if you remove the 500 spinner lamp from its socket and measure the resistance between the colored wire connected to that socket and ground, what resistance is it measuring? If you compare it to a lamp socket where the lamp isn't lighting up, is the resistance vastly different?

5. With the machine ON, and your DMM set to read to 5V DC, can you tell us what voltages you're reading on the Lamp Driver board on U1 pins 1, 2, 3, 21, 22, 23 and also the voltage on pin 23 of each of U2, U3 and U4 of the Lamp Driver board. These signals control which SCRs should illuminate specific lamps.

#16 5 years ago
Quoted from Quench:

I see in your first pic there's been some solder work on the PCB above the flyaway targets. Is that what you were working on when things started going wrong? Have you checked for shorts in the soldering?

What he said...which is what I said... I would check that first.

#17 5 years ago


Cut all the wires going to flyaway switches. No changes


Switches that will not close in test are right rollover star, inlane joker, right inlane special. Of course all three coin ins.


They flicker during MPU led flash test. Once you get the MPU fired up and a "ding" from sound board they stay on. So no, the do not fire immediately


No resistance is measured without lamp. With about 2.5 to 4. No differences between various lamps.


U1 pin1 .3v
U1 pin2 2.1v
U1 pin3 1v
U1 pin23 2.2v
U1 pin22 2.1v
U1 pin21 2.2v

U2,3,4 at pin 23 read 2v

Thank you so much for the help. I assume pin 1 in u1 should read higher?

#18 5 years ago

Regarding point 2.
See attached switch matrix below. I've filled in the cabinet switches in red. The blue circled switches are the ones you mention aren't responding in the switch test. Most of those not working are on the signal marked ST1 (Strobe 1). Can you confirm if the Spinner, Tilt and Slam switches are working? This signal is essentially derived from pin 3 (PA1 signal) of U10 PIA on the MPU board.

Regarding point 3 and 4.
Ok, so those lamps aren't on due to a short on the playfield.

Regarding point 5.
LDB U1 pin 3 being 1V is a problem. This is causing those spinner lamps to come on all the time. Infact the spinner 3000 lamp should also be on. Can you confirm if this lamp is blown?
However this doesn't really explain why other lamps aren't coming on so there's also another issue.
This Lamp Driver Board (LDB) U1 pin3 signal is essentially derived from pin 3 (PA1 signal) of U10 PIA on the MPU board.

Notice something in common here?

Now you've swapped the PIA in U10 with U11 and the symptoms didn't change. Note, this PA1 signal is also used for the displays and they're working, but it's wired a touch differently, so lets put that aside for the moment.
So something hanging off the PA1 signal coming from the U10 PIA is causing an issue.

1. Confirm if the spinner 3000 lamp is blown.

2. Confirm if the Spinner, Tilt and Slam switches are working or not.

4. Are any switches shown as always on in the switch test?

5. Measure the PA0, PA1, PA2 and PA3 signal voltages directly on the U10 PIA chip of the MPU board, that's pins 2, 3, 4, 5 respectively. We're interested in how the PA1 signal on pin 3 compares to the other PA* signals). It should generally be 2.0 - 2.5V in attract mode.

6. Do these same measurements again, however this time disconnect all three J1, J2 and J3 connectors off the MPU board. Wait till after the 7th LED flash on the MPU board so you know it's reached attract mode. This is to see what the PA1 signal is reading after having isolated the Lamps and Switches bus connected to it off the MPU board.


#19 5 years ago

Oh btw, Lamp Driver board U1 pin 1 measures 0.4V during attract mode on my early Bally. It measures 5V during the power on self test and drops to 0.4V as soon as attract mode starts. You might want to confirm similar behavior and that it's not stuck low.

#20 5 years ago

1. Lamp was blown at 3k spinner. New lamp stays on the same as other three now.

2. Spinner will not close. Not sure on tilt or slam, did not have time to check. Btw, right star switch was not working prior to this issue.

3. No stuck switches during test.

I will check others tonight. Thx again, might be onto something here.

#21 5 years ago

Cool, yeah right star rollover switch might just be dirty / gapped too much (it's a separate issue)..

#22 5 years ago

Oddly, slam and tilt will close during switch test? Pin 3 reads 1v, while all others read about 2v. That's in attract mode both with connectors on and off.

#23 5 years ago

Somethings dragging that PA1 signal down on the MPU board. It could be shorted to something from previous work done. Does it look like someones replaced the 40 pin IC sockets on the MPU board or any other work?

Look around the top right of the MPU schematic. There isn't too much connected to that PA1 signal. You can try disconnecting/replacing items if you have desoldering skills and equipment. If not, you could end up damaging tracks so you might be better off sending the MPU board to someone who can do it properly.

You still have the issue that no other switched lamps are coming on during attract mode right?

#24 5 years ago

U20B helps to multiplex U10 PA1 to also do display latch strobe #2. These kind of chips usually fail on the output, but maybe the input of U20B Pin6 is damaged and holding the line low.

See if the results change with MPU J1, J2, and J3 disconnected. A short on a display, lamp driver board, or even the coin door slam switch shorting against the coin door could do it.

#25 5 years ago

This board has had some work to repair battery damage. It does not appear any work has been done to replace sockets or anything like that.

We've tried removing the j1, j2, j3 connectors and pin 3 of u10 is still 1vdc.

I still have just a few lamps on in attract mode. 7 to be exact.

I noticed c58 had one leg broke off. I believe it is in the display circuit. Soldered it back down and it did not change the symptoms of the game.

#26 5 years ago

U20 is bad or there is a soldering mistake shorting two lines together???? The later seems more likely.

#27 5 years ago

The game worked for a few weeks so I'd say it is unlikely a soldering mistake was made. I can try to replace u20.

#28 5 years ago
Quoted from mtgedney:

The game worked for a few weeks so I'd say it is unlikely a soldering mistake was made. I can try to replace u20.

cutting the trace to u20 would isolate it out of the equation and is probably less invasive. U20 failures are usually at the latch strobe output side, not crashing an input it gets from the PIA.... but just throwing out possibilities. I wouldnt want you to change an IC that is not needed to be changed.

Is it a pulsing 0 to 5v with a DMM average reading of 1v or just a flat 1v (logic probe never light up red)?

#29 5 years ago

Flat 1v on dmm

#30 5 years ago

If it's not U20, some remaining items that connect PA1 to ground are R111 (56K ohm resistor) and C27 (390pf capacitor) via diode CR1.
So disconnect one leg of diode CR1, this will take out these 3 items from the PA1 circuit. It's sitting just above dip switch 32.
The non working switches still won't work but if there's something wrong there, the spinner lamps should no longer come on all the time and so you'll need to diagnose which of those 3 components is faulty.

If the spinner lamps still come on, the last remaining item on the PA1 signal to ground is C42 (470pf). It's about 1.5 inches to the right of connector J1. Disconnect one leg of this cap and see if the lamps still stay on.

Failing this, if you can provide clear detailed pictures (front and back) of the top half of the MPU board maybe we'll be able to spot something abnormal.

#31 5 years ago

Hey guys, I pulled cr1 and it restored a lot of the attract mode lighting. I don't believe it's all back but it's better. Any ideas on the switch matrix?

#32 5 years ago





#33 5 years ago
#34 5 years ago

Thanks for the pics. Nothing immediately stands out. What are the small brown stain spots on the top right area? Might be worth cleaning the area later.

1. Are you still getting 1V on the PA1 signal or has it returned to around 2.2V?

Lifting the leg on diode CR1 has disconnected the coins and other switches on that column of the switch matrix so that's why they're still not working.
The CR1 diode is the most likely component of the three so time to check it. Do it with the machine OFF and disconnect J2 and J3 off the MPU board.
While the diode is still disconnected, set your DMM to diode test mode. Put the black lead of your meter on the side of the diode that has the band (which is the leg you've lifted towards the J2 connector) and put the red lead on the other side of the diode. It should measure about 0.6V . Swap the leads around and you should get no reading (i.e. the meter shouldn't respond). Do the same with diodes next to it to get a feel and comparison of how it should read. If it reads differently replace it. It's a 1N4148 diode and they only cost a few cents.

If the diode measures ok, then measure the R111 and C27 combo to ground. Set your DMM to high resistance mode and measure the resistance across R111. It's at the top of the board above dip switch 32. It doesn't matter which way around you put the leads and should read 56k ohms. Compare it to R108 which is right next to it to get a feel. If it measures differently let us know.
Lastly just measure the resistance across C42 and make sure it's the same as C41 and C43 next to it. It won't tell you if it's out of capacitance, but might tell you it's shorted (although it's pretty unlikely to be at fault), but worth doing anyway to get a feel of the load on the signal.

#35 5 years ago

Unfortunately everything in circuit checks out. .6v at cr1. Blocks signal in opposite direction as the diode should. R111 shows 55k as do nearby resistors. C42 and the nearby caps measure out the same.

The pin 3 of u10 is now at 2.1v. I still have lights in attract mode along the right line as well as the entire bottom half of the playfield.


#36 5 years ago

1. Can you list which lamps on the playfield aren't working?
2. Are the Spinner lamps still stuck on?
3. If you disconnect the Aux lamp board, does it make any difference to the playfield lamps?
4. What resistance is R32 measuring on the MPU board? It's next to SW33 up top and is a 3.3k ohm resistor. On my boards it reads about 2k ohm in circuit.
5. Can you post front and back pics of the MPU board, this time of the right hand side middle to lower area? The PA1 signal on the other end of the CR1 diode also goes there to the J3 connector for the cabinet switches (coins etc).

1 week later
#37 5 years ago

Here is an update.

Well I bit the bullet and purchased a brand new Alltek MPU. Sadly, the machine exhibits the very same problems. No response from coin in switches. Nothing from right rollover star or card six up top (those haven't worked since I have owned the machine). Joker inlane and a few others now work. Fortunately I can start a game with free play mode.

The lights are exactly the same as they were a few weeks ago. Nothing along the right side or the bottom half of the machine.

Clearly we have been chancing our tails exploring problems on the MPU.

What is next? Any ideas? Light board?

#38 5 years ago

Ground issue on lights.

#39 5 years ago

With the machine OFF, have you checked with your multimeter that these non functioning switches are actually making electrical contact? With your DMM in low resistance mode they should read zero ohms when closed.

Spend a few minutes and check every diode in the switch matrix throughout the playfield and cabinet including tilt/slam switches. While you're there, check the capacitors on switches that have them looking for any that are shorted.

With your multimeter, measure for any shorts to ground against the lugs of the coin switches.
Make sure you've got continuity all the way from the MPU board itself to the coin switches. Presuming you've got a "Rev L" Alltek board, next to J3 there are some small surface mount resistors.
The right side of resistor R116 goes to one of the lugs on all three coin switches.
The right side of R125 goes to coin switch 1 (left chute).
The right side of R128 goes to coin switch 2 (center chute).
The right side of R124 goes to coin switch 3 (right chute).
Check all these for continuity.
If you've got a Rev K or older Alltek MPU board, the resistors are different. If you know how to read schematics, they're available on the Alltek site.

If you want to try, you can simulate a coin switch on the playfield by briefly jumpering a wire from the left outlane special switch (the lug that doesn't have the diode connected) to the playfield Tilt switch on the diode lug with no wire, that should simulate coin switch 2.

#40 5 years ago

Also regarding the lamps, did you try what Cheddar mentioned way above by shorting the SCR metal tabs on the LDB to ground to see if the corresponding lamp illuminates?

A few examples:
Q1 Right out special lamp
Q3 125k center cards lamp
Q9 Wheel flasher lower right lamp
Q10 5k right lane lamp
Q16 Ball in Play (backglass) lamp
Q22 10k right lane lamp
Q34 Wheel flasher lower left lamp
Q35 60k Bonus lamp
Q56 Right lane special lamp

Hey there! Got a moment?

Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside