Dolly – why won’t your switches work for me? – aka the Bally Pinball switch matrix

MPU Pre-Cleaning

I have been trying to figure out how to address the Bally switch matrix.  I have found (as I have recorded on my issue tracker) that I have 8 switches that aren’t responding.  I looked up how to build the visual diagram of the switch matrix – a grid of 5 columns, and 8 rows.  The first column (0/zero) has switches 1-8, the second column … Continue reading

Dolly – It’s Alive (again)!

Dolly Parton Backglass

The other day I was thinking about the 20k resistor that I didn’t have – and got to thinking.  “Can’t you run resistors in series or parallel to adjust the net value?” I thought to myself.  So, I called my dad as I thought that if you put them in series you then added the ohm rated resistance values together. I have an 18k, and … Continue reading

Bally MPU Corosion – Woes and Repair continues

MPU Pre-Cleaning

Well tonight – I finally got in the mental space to re-approach working on the MPU for the Dolly Parton pinball machine.  I was disheartened when I finished the installation of the U8 last week. I had verified all the connections were correct – and replaced the capacitor just below the IC.  Everything then tested as I expected, so with great hope I put the … Continue reading

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 … Continue reading

Bally MPU Corrossion – Woes and Repair

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 … Continue reading

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.


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Vector Mame Cabinet / Game Progress


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 … Continue reading

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 … Continue reading

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 … Continue reading