(Topic ID: 181445)

TZ - problem of multiple rows short


By jimy_speedt

2 years ago



Topic Stats

  • 8 posts
  • 3 Pinsiders participating
  • Latest reply 2 years ago by Coyote
  • No one calls this topic a favorite

You

Linked Games

#1 2 years ago

Hi,

After the gumball machine had died, I first checked the fuses and 2 of them were out, one for GI, one for flashers, as written in the manual. After replacement, the gumball now ejects balls (!) but I get two other problems

1. 5 rows are reported short at pinball switch on. In test, yes, all the cells of these rows are lit.
2. All the flashers are on and steady at pinball switch on.

The CPU is good. when I remove the switch matrix connectors, the problem is no longer reported. I checked each connector wire row/column with the ground, no contact.

Wonder how to proceed further. Any help is welcome

Thank you

#2 2 years ago

Unplug the 8-Driver PCB in the backbox. (Connected by the small ribbon cable.)

See if that changes anything.

#3 2 years ago

try unplugging your optic board.

#4 2 years ago

Hi,

When I unplug the 8 driver pcb, the problem disappear.

By opto board, you mean 10 opto pcb ?

Thank you for the help

#5 2 years ago
Quoted from jimy_speedt:

Hi,
When I unplug the 8 driver pcb, the problem disappear.
By opto board, you mean 10 opto pcb ?
Thank you for the help

Okay - then:
(1) Likely, your ribbon cable is flipped. Check, Double-Check, and Triple-Check that when you plug the ribbon cable back in, that the RED LINE on the cable goes towards the "1" pin on the CPU and the "1" pin on the Driver board.
(2) If you are very, very, *very* sure that they are, and you still have the problem, reverse one of the plugs.
(3) If there's no change, you will need a new 8-driver PCB.

#6 2 years ago

Ribbon cable badly plugged, in the correct orientation, but not fully inserted.

Big mess little problem (that I did not figured out)

Thanks lot for the support.

If you have one minute, can you explain to me which information is sent to this board and why the switch matrix can be messed up ?

Thanks again

#7 2 years ago

yes, but it sounds like you found your problem.
I had a dr who, that the optic board had burnt up and sent short to ground messages.

#8 2 years ago

Sure -
That's because the 9th column (which is for the Clock Optos) is driven by one of the outputs on that board. By plugging the ribbon cable in backwards, the signals getting to the board are corrupted, and causing that column driver transistor to always be on, which would then cause the 9th column to always be grounded. When an opto on that column was NOT blocked, that ground would then be read by all the other rows, scanning all the switches, and cause it to report that.

Quoted from wdennie:

yes, but it sounds like you found your problem.
I had a dr who, that the optic board had burnt up and sent short to ground messages.

Yup! Since an opto board connects to a specific number of columns, and all rows, a bad driver or blown board can cause the same thing.

The key was he stated some flashers were stuck on as well - like the column driver, other transistors drivign the flashers would be stuck on, causing them to always light up.

Promoted items from the Pinside Marketplace
Wanted
Machine - Wanted
Tinley Park, IL
From: $ 149.00
Playfield - Toys/Add-ons
Sparky Pinball
From: $ 175.00
Gameroom - Decorations
Pinball Photos
$ 15.45
Gameroom - Decorations
KAHR.US Circuits

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