Dolly – Bally MPU U8 progress

With the help of my friends at GAPAS I was able to determine test points and continuity areas of my Bally MPU for the Dolly Parton pin so that I’ll be able to put in jumpers where necessary to resolve the problems with U8.

However, while testing I found that pin 8 and pin 22 were showing continuity. I was pretty sure this shouldn’t be the case, but as I have only this Bally pinball machine – I have no other MPU to test against.

Today I was able to get my friend Robby to help me – as he has a few.  He verified that there should not be continuity between 8 and 22 as I suspected.  But then there is the issue with – well why are they connecting when they shouldn’t.

I knew that pin 8 was supposed to be connected to ground for the power portion of the circuit.  And it looked like 22 should have been to a positive power source – and after checking pin22 did seem to test good to the little through hole solder junction on the board (with a + sign next to it).  Of course this wasn’t foolproof as I was testing continuity between that + and ground… which is a big obvious NO NO.

After having stared at the board so long while determining the pin out connections – I was thinking perhaps it was a bad capacitor.  C13 seemed to stand out to me – it is near the battery, and could have been damaged some way from the acid problem.  Or, perhaps, it was due to heat or some other from when removing the IC stand at U8.

I cut a lead off the capacitor – and like magic no more continuity between + and -.  Now, I’ve added a new 0.0uF Axial Ceramic capacitor to my shopping list for this week at the electronics component store..

Hooray for progress, and thanks again Robby.

Bally MPU Corrossion – Woes and Repair

U8 image

U8 image

I’ve cleaned up the corrosion on my Dolly Parton MPU (Bally) – BUT Some of the traces were really damaged and a few I can’t determine where they should connect, and others might not have continuity any longer.The only component apparently affected that I have had to replace and am concerned about is the U8 chip.Unfortunately I can’t read a schematic well enough to figure out where on the board I should be checking.

I’ve been looking online for a quick guide of what to check and where each pin should connect on all the normally damaged components as this is a REALLY common problem with Bally’s, BUT I haven’t found anything that will really help. Basically a trace diagram for the MPU would be awesome but alas I’ve not turned one up.  And I’ve not found high enough resolution images of the front and back to work from reliably.So, does anyone know off the top of their head where all 22 pins on the U8 should have continuity to?  🙂  If I need to add jumper wires it would be awesome to know where they should land.

I’ve been trying to map this out and here is what I have so far.  I know some of the legs should have continuity with other legs on the same chip – but not 100% sure which those might be, and if the pair also should have continuity to some other component.My notation is IC / or resistor/capacitor #.  e.g. U7.1 = Chip U7 Pin 1

1 – U7.20
2 – U7.21
3 – U6.6
4 – U7.23
5 – U7.18
6 – U7.17
7 –
8 – GND
9 –
10 – U11.29 (??Paired with 9?)
11 – U11.28 (pair12)
12 – U11.28 (pair11)
13 –
14 – U11.68 (??Paired with 13?)
15 – U11.26 (pair 16)
16 – U11.26 (pair 15)
17 – U18.6
18 – U17.8
19 – U17.6/ U10.23
20 – U18.7
21 – U6.4
22 – R12 left leg (also Big pad which I believe leads to Batter + terminal)

Do Pins 11 and 12 only link to the other? Should there be a connection anywhere else? As you can see I’m missing a couple which I’ve not been able to identify.


One of the GAPAS members (Ken) sent me the following based on his review of the schematic:

1 – (A3) U7.20 / U6.5
2 – (A2) U7.21 / U6.6
3 – (A1) U7.22 / U6.7
4 – (A0) U7.23 / U6.8
5 – (A5) U7.18 / U6.3
6 – (A6) U7.17 / U6.2
7 – (A7) U6.1
8 – GND
9 – (DI 0) U11.29 / U7.6 (pair 10)
10 – (DO 0) U11.29 /U7.6 (pair 9)
11 – (DI 1) U11.28 /U7.7 (pair 12)
12 – (DO 1) U11.28 /U7.7 (pair 11)
13 – (DI 2) U11.27/ U7.8 (pair 14)
14 – (DO 2) U11.27/ U7.8 (pair 13)
15 – (DI 3) U11.26 /U7.9 (pair 16)
16 – (DO 3)U11.26 / U7.9 (pair 15)
17 – (CE 2) U10.34 / U11.34
18 – (OD) U18.6
19 – (CE 1) U17.8
20 – (R/W) U18.7 / U10.21 / U11.21
21 – (A4) U7.19 / U6.4
22 – (VCC) R12 left leg (also Big pad which I believe leads to Batter + terminal)
The (A)ddress lines and (D)ata lines will go to multiple chips.

QUESTION: should I be getting continuity between 8 (gnd) and 22 (VCC) ? If not then I’m wondering if I need to replace C13

What to do today – Arcade Game or Pinball Machine restoration?

Not sure what I want to work on tonight.  Both Missile Command and Dolly Parton are in need of some board work, and physical game work.

Need to rebuild the power section on the Missile Command, and track down the fire button issue for player 1.


Dolly Parton has some switches that need to be debugged. I suspect it is due to the acid damage on the MPU – which will need cleaning and evaluation.   It could also be something on the driver board if all switches are in the same column or row. I’m hoping the switch issue resolves the kick out saucer problem at the same time.

Decisions decisions.


[yop_poll id=”2″]

Vector Mame Cabinet / Game Progress


Control Panel Overlay for Space Duel Vector Mame

I decided to get to work on a project that is long over due – my Vector Mame machine.

Years ago I had purchased a Space Duel cabinet with some of the beginnings already laid out to convert it into a multi-vector game.  I had found a PC and loaded up all the software, spent some hours configuring it.  But then had some frame rate and sound issues.

Circumstances changed a bit with priorities and the machine ended up sitting in my garage for a couple of years waiting patiently for me to get back to it. But, Jeremy and I bought the house downtown and in the process of moving – the PC that was driving the system disappeared.

So, I was left with the cabinet and monitor, and the ZVG board – but no PC with a parallel port and a SoundBlaster card.

You see the difficulty is – this system requires true DOS mode to function – and only a select handful of sound cards work in DOS mode.  This along with needing a working parallel port, and a serial port – it has been a while since I’ve wanted to really face this challenge again.

Fortunately my friend Alex had an old pc which I’ve re-purposed from running Windows XP to powering my game.

I don’t recall where I have my old DOS 6.22 disks any longer – so I thought I’d try Freedos and see if I could get it to work.  The installation was so quick and painless I was shocked.  Then was surprised yet again when I set to start configuring things and all my old DOS command line skills proved to be intact.  I might not remember anyone’s phone numbers but I can still remember that a sound card needs an address, an IRQ, and a DMA and how to set them.

I unfortunately don’t have a SoundBlaster – but I could get all the primary setting configured outside of that and ensure that the ZVG driver board, the monitor, and the controls still work.

Spent probably and hour and a half on the reformatting, copying, configuring each component and then connected this PC to the machine.  Ran a few utilities to ensure that I had my brightness and screen scaling set correctly – and gave it a go.

I breathed a sigh of relief when my test pattern showed up correctly. I fiddled with the focus a bit and was ready for phase 2 – starting DVMame (Dos Vector Mame). I started the program and was happily greeted with the menu system I had choosen, but I wasn’t able to select things as I’d hoped.  I mashed buttons and wondered if I had lost continuity or a wire had come loose some how during the move and the years of sitting.

I opened the control panel and traced the wires – they all were connected.  Finally after another hour and a half of poking, looking on the internet, poking, reading more, mashing buttons, and so on I found the keystroke combination that would allow be to enter the configuration settings for the control panel.

I had 2 buttons that weren’t registering correctly – so I restored the components to factory settings then rebooted the system. The buttons registered the keys they should – and I was ready to give Mame a go again!

All the stars aligned and the menu came up – and NOW all the buttons worked as they

should and I was able to start some games sans-sound. HOORAY for progress.

I found 2 older sound cards – I thought I’d give them a shot.  So I got a Diamond Monster II card and found the DOS mode drivers from a Windows98 setup archive. Copied them to CD (I’ve gone though 6 or so tonight ferrying new bits of data to the new/old game control PC – and each one has to be finalized so I can’t just add more data to a previous one — annoying).

I make sure I have the IRQ/DMA settings unique to the sound card, have my set BLASTER= correct in my autoexec.bat along with my SET ZVG to the system LPT1 IRQ/DMA port settings – and booted up.  It took a few minutes to get things working right as this card is looking for a not included .ini file that I had to generate by hand from the cryptic error messages I was being given.

But finally everything re-booted and came up error free.  Crossing my toes (as my fingers were busy) I decided that I’d give it a go and fired up my menu so I could select a game. Things seemed good – I had no speakers attached yet, but if the drivers loaded, and the game runs – that is my next step.

I select a game – press the start button, and the screen goes HaYWiRe and promptly blanks out.

OH NOssssssssssss

Stop the emulator, power everything down.  Reboot, try to bring up the menu – and dead.

I remove the sound card driver – reboot.  Start the game system  – it has not had a spontaneous Lazarus encounter and the proverbial stone has not rolled away.  The monitor on the arcade game is still dead and not responding.

I find the configuration application for the ZVG card – and start it.  I want to know if my card is dead or if the problem is something else.  Once the utility starts I see all the values are completely wrong.  I press the key to reload factory defaults and the monitor buzzes slightly – and comes back to life. I re-configure the settings, and my test pattern is back to what it was – This time I make sure to save these as a backup in case I need them later.

I run the game menu system again -without sound support and all the games come to life and are all playable – just like if Marcel Marceau had been the contributing sound man.

So, I’m back to where I was hours ago –  FreeDOS works generally. I don’t know if the driver conflation was a result of it not being actual windows, or the if the sound card itself is doing more behind the scenes than I want.

I guess my next step is to find the most basic Sound Blaster PCI 512 type card that I can, and see if that resolves the problems – or if it is the operating system perhaps.  I don’t want to re-re-rebuild the system, but I have all the software laying about here and there now.  I might go for Windows95 install if i can find find some media as DOS 6.22 can be a real pain to install off CD directly.

(And in the midst of all this flailing I’ve found that the motherboard tends to freak out every 3rd or 4th boot – it displays messages like “New processor detected”, or a case open intrusion alert.  I’m thinking the CMOS battery is going/has gone out and needs to be replaced.  I have another motherboard that might work – so I’ll give that a go in a day or two.  I’ve had all the drama I can deal with for one night.)


p.s. if you have a real old basic CreativeLabs Soundblaster you want to donate let me know I think I have $5 left somewhere…

I want more than a ghost memory of my Pacman machine

So, I’ve had a Pacman machine for some 6 years.  A few months before we moved from Woodstock (GA) to Atlanta it had suddenly stopped working.  I checked to make sure the power supply/transformer were working. Checked the fuses – but all it would do is light the marquee and there was power to monitor.  There was no sound, no video – nothing to diagnose against.

After a few days of fiddling was distracted and just let it sit in its own petulance.

I gave it a go again after we moved into the new house and had setup some games in the basement.  No love from Pacman.  I asked friends and posted a bit for help here and there, and searched for any troubleshooting guides that listed my problem.  I even had my friend James come by one day to help me with my pins, and he spent some time looking at it and couldn’t come up with any rapid solution.

So, again it sat. dead. mocking me, and my inability to fix it.

I had gotten re-acquainted with a contact who specializes in video games. I asked Chris if he’d help – and he agreed to. He took the main board home to test, and gave me the bad news – he couldn’t fix it either. He swapped out his chips for mine, and it still didn’t work.

I posted recently on GAPAS and asked if anyone might have a replacement or know of someone who could do the repair. One member responded that he had a board I could buy.


I went and picked up the board from him, and of course got too busy to dedicate the time to exploring the swap.  I also met back up with Chris and got my old board back – you see it has a Multi-pac kit. So rather than just playing Pacman it also plays Ms. Pacman and a number of other versions and variations — some 24 in all. I think my favorite just for the odd factor is Dead Ms. Pacman which is essential zombie Ms Pac and zombie ghosts.

Tonight I had the time and perhaps more importantly the inclination to do the installation.

I read the instructions and removed the chips instructed.  Installed the multi-pac octopus of little boards and wires and plugged it into the machine and turned it on.

I ran around the front to watch the first images come up on the screen, and was greeted with static type noise and no video. Refraining from unbecoming language I turned it off, and then thought it again. I might work. With quasi hopeful expectation I pressed the power and was immediately greeted by the static garble whining noise and turned it back off.

Dejected I return to the workbench and think back through the installation. I thought I heard a bit of a pop earlier that seemed odd – and it stands out.  So, removing the primary daughter board I look at the stand off it is in, and think that I have another so I’m going to swap it out. I pry off the old orange brown piece of electronics and set the legs into a new one.

I carefully pressed this into the slot where it belongs. Re-install the board set into the video game cabinet and with less expectation but as much hope press the power button.  I wait, and no noise. Hesitantly I walk around and wait for the monitor to warm up – and am greeted with the game selection menu.

I nearly do my Dr. Frankenstein, “IT’S ALIVE” impression.

Happily I play almost one of each version of the game. Satisfied that things are fine I decide to have a glass of wine and relax.  I’ve had enough tension the past few days with games.

Now, how did those patterns for Pacman go again that I used as a kid in the 80’s


Out of Contact… a pinball sayonara story

Contact image from

Well, my Williams Contact went to find a new home this weekend. I turned it on to play a few farewell games and enjoyed it exactly as I expected. This is the first working pinball machine that I had repaired that I’ve parted with. I had found a beautiful playfield and built a shockingly pristine playing and looking machine.

I think for most pinball machines (with the obvious glaring exception of Raven) if you come to it knowing what the game offers and aren’t wishing it was something else that there is fun to be had. This game is not a complex “Deep” game. It is a fun beat the ball around and score points game.  I find the multiple lines of bonus building to be fun and interesting.  And to try to keep the highest line your actual bonus score should the ball drain.

Took the head off. Removed the legs.  Carted the who thing up to the BMW and got the pin (a widebody) in, along with the dolly to get it positioned once it got to Alexe’s .  The head of the machine was laid on top of the playfield glass on top of a blanket.  I drove with the fear that someone would rear-end me, and the head of the game would come flying forward as a missile and decapitate me.  I kept making sure it was lined up over the empty passenger seat at every stop.

So, after the fortunately uneventful drive to Alex’s house we got it carted successfully into the newly designated game room. We put on the legs, we attached the head – then unattached it and fed the power cord through the slot and bolted the head back into place.

We pulled the wire bundles and plugged them into the appropriate connectors. Careful to not mis-connect anything we turned it on – and Nothing.

It appears to be having separation anxiety though as when I went to set it up at it’s new home it decided to start sulking.

Well, that wasn’t what I hoped nor expected to happen.

Disconnected everything.  Plugged them all back in including reseating the connector between the driver and MPU boards – found one playfield to driver board bundle that hadn’t been connected and hoped that was the problem – but alas not.

So, after running out of time – I abandoned the game to the whims of fate and hope to figure out what could have happened in the moving process as nothing is coming to mind.

I was so distracted I left the moving dolly sitting in his game room and drove home.

If anything stands out to you as a likely cause for this on a previously working Williams System 3 pinball machine I’d love your input.


Site Navigation Update

I have added a new menu item to easily bring up the task lists that parallel the Current Machines – Current Tasks so that it is easy to see what has been done, and what is pending with each machine.

Previously you had to navigate to a given machine’s page to then find the task list link.  Also, now there are blank lists for each item in the collection if there are no current or historical tasks.

Dolly – There she is

Prior to any committed pinball machine repair I finished the first initial cleaning to get an idea of how the game will look.  The amount of grime that came off was pretty impressive.

I still need to decide if I want to do any touch-ups at this point cosmetically or not.  I’m inclined to just apply wax to it at this point and let it be, and come back to this in the future.  The cosmetic issues on the playfield are not as important as dealing with the switch and battery issues.



I’ve been considering migrating my games at least partially to LEDs

The technology has improved greatly over the last few years since they were initially introduced for use in pinball machines. Particularly where older pins not designed for them are concerned.

My thoughts fall into the following catagories:


  • The introduction of Frosted dome bulbs helps with the hot glare points.
  • Much lower power consumption – GI and playfield lighting can be your biggest power draw.
  • Less heat output – protects valuable game resources.
  • Colors – Colored LEDs below playfield inserts can really brighten up a game and enhance the feel


  • The bright light points can be VERY annoying – particularly on playfield GI where the bulb is visible to the naked eye.
  • Old LEDs didn’t have the same light dispersion directional control as bulbs.
  • Light can be very harsh – bulbs are a softer yellow light that our eyes are accustomed to seeing