*Solved* Bally -35 crazy feature lamps

[Moonbus]

Game: Mr Mrs Pacman.
Condition: No cabinet, purchased as playfield and a box of bits. MPU was toast from battery damage. All other boards ok.

Story so far is documented here...
https://pinside.com/pinball/forum/topic/mmpc-first-ss-second-pin-coffee-table

The issue and question:
Upon power up the game boots, all displays function correctly. Can add credits and start a game but not in a position to go further as assemblies not installed.

If I leave the game in attract mode it will wait the required time then start the attract sequence. Once the attract sequence has finished all hell happens with the feature lamps. It is like a Christmas tree on acid.

This is with LEDs and incandescent lamps. It is not strobin or ghosting it is like a scene from poltergeist.

I replaced U14 and C16 and the timing circuit seems to function correctly.

I'm assuming the MPU boots to 7 flashes, the processor then starts the attract sequence and when it gets to the end of that program loop something goes wrong.

Has anyone had anything similar happen or has anyone got some suggestions on trouble shooting?

 

[carl lawrence]

We need that shop log on here dude it's awesome

The wires you circled are correct ,but I think that led in the second pic should be a a 555 lamp !

If I am correct in saiding this one lamp help the sol explander board work correctly ,change this back to a lamp and your problem may go away possibly
And this one too

 

[Moonbus]

We need that shop log on here dude it's awesome
View attachment 50724
The wires you circled are correct ,but I think that led in the second pic should be a a 555 lamp !
View attachment 50727
If I am correct in saiding this one lamp help the sol explander board work correctly ,change this back to a lamp and your problem may go away possibly
And this one too
View attachment 50725

I'll have a look thanks.

I don't have any online photo storage so linking photos to here would require me to set something up. I guess if I'm going to get myself into these situations I should have a better way of showing the issues.

 

[Moonbus]

Just realised that the pics you are referring to were added by someone else to help me with some wire locations. I have put the lamps in place.

I tried some stuff this morning.

Re-flowed all the headers on MPU, lamp board and aux lamp driver and tested continuity with the connectors.

Ran the game again and left it in attract mode. Same issue as before happened. I left it on for longer and after a few cycles most of the feature lamps stopped working apart from the red on the pacmaze and one of two others.

turned off the game and disconnected the lamp driver board. Left the Aux lamp driver board attached. Started the game again and the feature lamps associated with the Aux board all worked perfectly and remained working for over 10 minutes.

So where does this leave me...
I think this proves that the MPU is working as it should as the Aux lamp board was receiving instruction as it should.
The Aux lamp board is working as it should.
The main lamp driver board is either not working or I have wired it up incorrectly to the playfield (I had to remake the playfield harness).

I re attached the main lamp driver board and started pulling wires from the J4 connector on the main lamp board. This is the link from MPU to lamp board. When pin 17 was pulled the feature lamps seemed to work almost perfectly.

Im still lost but hopefully I am narrowing down the search area.

 

[Moonbus]

Ok, by the powers of deduction. Given that the Aux lamp driver and the Main lamp board share most of the same signals I think we can assume that any signals used by the Aux lamp board are good as those light behave.

That leaves these two not used by the Aux board.

Address line 3 and Strobe 1.

Logic probe at the ready!

 

[astyy]

I feel for ya moonbus, I'm re-wiring a Vector using Eight Ball and Elektra donor looms. Vector is one of the most populated Bally SS games so switch on day is going to be interesting.

 

[Moonbus]

I feel for ya moonbus, I'm re-wiring a Vector using Eight Ball and Elektra donor looms. Vector is one of the most populated Bally SS games so switch on day is going to be interesting.

Yeah, it is so frustrating. Big problem I have is not having any working alternatives to swap in, or another machine to drop bits into to test.

Part of the fun though isnt it

I have molexed all the mech's on the underside of the playfield. This makes it easier for me to introduce things slowly whilst reducing the chances of a short as well as make it easier for me to swap mech's and assemblies from one game to another.

Good luck with yours and remember to leave some slack in the cables, makes future work so much easier.

 

[Moonbus]

- Solved -
I found this video where the 555 timer is checked...

Put the scope on mine and it was was acting strange. Replaced the associated capacitor and resistors and got the 555 pulse time to 3.2ns.

When I ran the game the same symptoms as before happened but at a more sedate rate. More in time with how you would expect lamps to flash in attract mode. The order of lamps comming on was just messed up.

I then replaced the U10 IC holder with SIP strip and hey presto all seems to be ok.

Thank you to those who threw in ideas, much appreciated.