BALLY SEVEN DIGIT DISPLAY EXPANSION INFORMATION

Bally / Stern replacement MPU Revision 15 and later supports seven digit displays with some wiring modifications for the following games.

Dolly Parton
Future Spa
Harlem Globetrotters
Kiss
Mystic
Nitro Ground Shaker
Paragon
Playboy
Rolling Stones
Silverball Mania
Space Invaders
Six Million Dollar Man
Viking
Voltan Escapes Cosmic Doom

Because these games use the PIA port that is normally for digit 7 to control the sound board additional hardware and software is required for seven digit displays.

7 DIGIT DISPLAY SETUP INFORMATION

EXTRA ITEMS REQUIRED THAT ARE NOT INCLUDED WITH THE MPU:

22awg wire
Wire insulation. Shrink tubing or equivalent.
Zip wire ties.
1pc - Four pin 0.100" Housing. Molex 22-01-2047 or equivalent.
3pcs - 0.100" crimp pin. Molex 08-52-012 3 or equivalent.
4pcs - 0.156" crimp pin. Molex 08-50-0108 or equivalent. *** If your game is using IDC connectors at the displays you will not need this.
7 digit displays. Plasma or LED will work fine. If using Stern 7 digit plasma display board solder bridge connector pin 11 and pin 12 together.

INSTALLATION

Run a new wire to pin 12 of each display connector. Start at the last display in the wiring harness run and follow it between all seven digit displays (not the credit display). If you have IDC connectors use a punch down tool or a flat blade screw driver and let the wire pass through the connector except for the last display in the wiring harness run. If you have molex connectors preform a double crimp at each display besides the last one in the wiring harness run. Keep the wire long enough past the first display in the wiring harness run to reach the top left corner of the backbox. The green wire in the picture below is the added connections.

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Move MPU J1 Pin 5 to the new added connector MPU J6 Pin 1. This is a typically a white wire with no stripe for digit drive five. You may need to extend the length of this wire if it will not comfortably reach MPU J6.

Move MPU J1 Pin 6 to the new added connector MPU J6 Pin 3, This is typically a white wire with a black stripe for digit drive six. You may need to extend the length of this wire if it will not comfortably reach MPU J6

Connect the wire you ran between pin 12 of each display to MPU J6 Pin 4. This is for digit drive seven.

Move both display count jumpers from 6D to 7D. 7D jumpers is only used for the special 7 digit expansion software, otherwise 6D is always used.

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Zip tie and add all the extra wiring to the wire support clips.

Set the game software to the seven digit display version and turn on MPU game option DIP switch 21. See the game selection setup sheet for more information about software.

Install the seven digit displays and you are finished.
Over exposed image to see all digits lit up.

Thank you Oliver Okaegi for the idea and software.

*** Note about Meteor Seven Digit *** Wire digit seven of each display to MPU J1 Pin 7.

MPUs can be purchased in the Pinside marketplace or at https://nvram.weebly.com

If you are using 6 digit player displays you cannot have the 7 digit display mode dip switch enabled. If you ever roll the game it will try and display the 7th digit which ends up making digit 5 and 6 in the HSTD look corrupted as those two digits are used to decode digit 7. MPU Dip switch 21 should be off when using original six digit displays.

Also clear / reset the memory for HSTD and replays after you change the MPU 6 digit or 7 digit dip switch setting.

Note about the "display interrupt adjust" trim pot. Near the bottom on the mid right there is a blue colored trim pot. This adjusts the rate that the displays are updated. Turning it clockwise will make the displays update more often. When six digit displays are used you want it somewhere from the middle to all the way counter clockwise. When seven digit displays are used you will want it somewhere from the middle to all the way clockwise. Put the game in display test and adjust the trim pot until the displays look the best.

Because seven digit games have more display date to update they can have a perceived flicker when the display interrupt is set slow. The flickering is exacerbated in games like MR/MRs pac that have 7 digit displays and extra playfield display. One side effect to increasing the display interrupt speed is that because you are having the CPU work on the displays more often other things can slow down. Most things will not change speed but some time based features, like the time between the space invaders thumping noise, can vary with the display interrupt trim pot setting.

There is a test pad you can measure the display interrupt frequency at. 320hz-400hz is fine for 6 digit games. 7 digit games 360-450hz is good depending on the game. For 7 digit games best way to set is by adjusting the trim pot during display test until the displays look best. 6 digit games will look good at about any frequency, but too fast may slow down some game features. If I know what game the board is going in I usually dial in the display interrupt for that game before sending it out

Note about Embryon 7 digit mod. This game is wired up like Meteor. The digit 7 drive is hooked up to MPU J1 P7 and the extra J5 plug is not used.

The credit display stays as six digit always.