Funky Town and more great songs

Friends of ours were in town for a wedding that we all went to this last weekend.  I wanted to thank Matt and Kate.  They brought down a number of 45’s for use in the Jukebox.

Now that I have found that the component that is dead in mine has an aftermarket replacement available I can get to work on it again, and hope to make some forward progress very soon.

Thanks so much guys 🙂

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

MPU Pre-Cleaning
U8 image

U8 image

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 (1/one) has switches 9-16 etc.

I have laid out all the switches based on the game manual and number allocation assigned to each switch – and have determined that 7 of the switches that are out are all on the same column (switches 17, 19-24 – switch 18 is unused), and then switch 34 for a 30point rebound is also out. If this was a Williams game I’d know better how to approach the problem, but Bally addresses the issue of switch management differently – particularly in relation to the matrix.  I know it is handled in one of the two PIA chips (U10 I believe).

I have determined that connector J2 Pin3 is the one that feeds the column.  Now what, not 100% sure :).  I’m guessing I need to make sure I’m getting continuity somewhere else – but haven’t determined that yet.  It is 1am, and I’ve been working on the game for 3+ hours at this point.

Hopefully, one of my great friends will have an idea of how to resolve this.

Dolly – It’s Alive (again)!

Dolly Parton Backglass

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 I have some 1k’s – I need a 20k…  So, I soldered the selected ends together (after calling my dad to verify) and put them in. Hoping against hope – I put the board in the machine and gave it power.

I had the machine  where the LED (which indicates boot status success/failure) to be constantly on. I counted this as progress.

Tonight though I had some more time

So, I re-verified all the continuity points for my U8 IC on the MPU.  And of course found a number that needed to be updated.

If you are a follower/reader you know that I recently determined there was more corrosion damage than I had originally thought (in my haste). So, I spent the past few times that I’ve had free to remove that, and install a socket for the U7 chip.

After this process the LED got through the flicker and first flash.  YAY – there needs to be 7 successful flashes for the game to boot up as each one indicates a phase completed.

Energized with my success I realized that I had not verified continuity on the U7 socket that I had replaced. And remembered belated that there was a trace that had evaporated in the corrosion cleaning phase under U7.  I found one leg of the IC completely isolated from the game – figured what points it needed to connect to.  Verified each of the other 21 legs on the chip – and after 2 hours of testing and soldering I decided to hold my breath and plug it in again.

Watching the LED like a hawk – it flickered.  Then flashed… once..  after a bit of a pause it flashed again, and again, and again, and again, and again, and again – and then there was a sound sequence, and the scores lit up.


The game is now in the same playable state as it was when I received it – but it not longer has the battery leaking more corrosive gasses and destroying the game.  It now really looks like  a Frankenstein machine with trace wires crisscrossing all across the back.  It isn’t pretty, but it is working – and I didn’t have to spend $200 to replace it.  I can live with not so pretty when no one will see it unless they pull the board out of the game.

Now.. time to run down the switch problems…  (next post)

Bally MPU Corosion – Woes and Repair continues

MPU Pre-Cleaning
MPU Pre-Cleaning

MPU prior to cleaning process

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 board in the pin.  My hopes were dashed when I powered the game on. Nothing happened other than a bit of beeoooop noise once. I flipped the power a couple of times – not expecting anything different, but hoping.

Dejected I took the board out, and placed it on my card table work bench.

So, a week later (today) I got the gumption up to work on the board again.  I figured the reset section was not working correctly.  The green LED comes on, but doesn’t go through the flicker/flash boot sequence.  So somewhere something in that section must be out of whack.  This is not coincidentally the same section that is usually directly affected by corrosion.

Today – I cut out and de-soldered everything else in this area. Imagine my surprise when I went to remove one of the larger resistors in this section the lead popped right off.  Apparently there was more corrosion problems than I had assumed.

After sanding, scrubbing, cleaning I began to put in all the replacement parts that I had purchased last week for this section.  I spent about three hours on this process I had one spot left for a resistor. I was annoyed after going through my entire box of parts and rechecking the bands on every loose resistor that I have.

I need to purchase one 20k ohm resistor to finish this project. Annoyed as I had gone with a list to the great local supplystore (ACK Electronics), and thought I’d purchased everything needed… but it appears I missed one item.  I did get one resistor that didn’t match anything on my list – so it must be what’s wrong.

Guess I’ll be back to the store this week unless someone has one on hand they want to drop by. 😉

I had been hoping to see if this would bring the machine back to life – but it’ll be a bit longer until we find out.