Bench test fixture

Bench test

Troubleshooting CPU & drivers boards

Allows an easy diagnosis of failures.

For SYSTEM 80, 80A and 80B.


At the origin of our bench test fixture, first there was a "simple" test board with a µ-controller PIC and a LCD display.

Plug in place of the 6502 CPU, it is then possible to drive all the circuits of the board to troubleshoot. To complete the set, an HEXA display addresses/datas based on TIL311 was installed on the TC1 location.

Test board

This version has then evolved into something much more complex...

We have added buttons and switches to simulate contacts (A1J5 and A1J6 connectors):

  • Standard switches matrix (SW00 to SW77)
  • Services buttons (REPLAY, monneyers)
  • TILT and TEST

We also add the opportunity to drive the audio cards with a series of dedicated switches (S1 to S32).

Drivers board

A second card with a screen LCD 2 * 20 was installed to test the card drivers. All outputs can be controlled individually and can also test its operation in the pinball.

It selects the model of pinball and the test displays plaintext which is current (for example: 1000 points lamp, high ejector), with aside the number of output.

The time of activation of outputs depends of the type: coil is enabled 1/10 second, 1 second for lamps, 2 seconds for motor, etc... This allows to check among other things that the wiring of the pinball is correct.

Screen of test drivers board

Displays board

A third card with an 4*20 LCD screen was installed to simulate the displays. Thus, there is no more need to connect a pediment to completely test the CPU boards.

Display board

This card connects via the A1J2 and A1J3 connectors and automatically detects the type of display. All displays are simulated, as well the digital 6 and 7 digits of the SYSTEM 80 & 80A, as the SYSTEM 80B alphanumeric.

"RAVEN" (80B) CPU initialized with our test-init modul:
RAVEN display


Prototype integrated in the housing desk:
(the last board is still missing) Bench test fixture

Inside and back panel:
Inside the bench test fixture Back panel of the bench test fixture

Final result

The finished bench test fixture
in situation with a CPU board and the leds modul:
Bench test fixture Bench test fixture


Originally planned to test some 6502 based boards, it was possible with some modifications, to also test 6503 based boards. Our bench now allow to test the audio boards MA-55, as well as the CPU of the Spectra IV cocktail tables.

Test a MA-55 sound board:
Bench test

Test of a Valley SPECTRA IV CPU board:
Bench test

Our test bench has enabled us to troubleshoot a cocktail Valley SPECTRA IV table. This board need of an alternative input voltage to operate, we reused our injector modul for Bally.


This achievement is not publicly available, in any form whatsoever (free or paid).


Last update of this page: August 7th, 2018

French Tech


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