Test module with leds

Leds Modul

Simple tool for maintenance.

Some leds, same number of resistors, a connector and a prototype board...
It's enough to build this device allowing a fast diagnostic of the CPU board.

For SYSTEM 80, 80A & 80B.


This module is used in troubleshooting, to ensure the functioning of the CPU board (A1) very simply when it is unmounted.

It is enough just to look at the lights, without having to connect the table, or card drivers (A3). These indicate the status of the solenoids control signals, sounds, and lights.

The absence of lighting of the leds indicates a problem at the level of the CPU board (the CPU does not start or U6 is burned).

Leds modul

From left to right, the leds correspond to:

  • State of the solenoids (9 red leds)
  • State of sounds (4 yellow leds)
  • State of the lamps - strobes and controls - (12 + 4 green leds)
  • Presence of power (1 red led)


As is seen, our mounting has been achieved by making the funds of drawers and its schema is very simple (click on the image to enlarge):

Schema LEDS

Leds are connected on the one hand to the ground, the other a pin of the connector through a resistance. The value will be chosen depending on leds and the desired brightness (for example 100 Ω for the Green, 190 Ω for red).

Preferably use rectangular leds, easier to have one next to the other.


The mounting plugs directly on the connector A1J4 of the CPU card, instead of the ribbon wires connecting the drivers card (A3).

CPU board

Note in this photo, the presence of another device installed on TC1 and which is also very useful for troubleshooting: the test-init modul.

Enhanced version

After several years of good and loyal services of the prototype, we finally offered to this assembly a implementation on printed circuit.

The module now has a flat connector and the layout of the LEDs has been revised The finish is now much more "professional". Module with LEDs We also use a female/female adapter to connect the card directly without using the original ribbon.

Module with LEDs Module with LEDs

The activity of the card is directly visible on the LEDs (strobes of the lamps, solenoids, sounds). During normal operation, the LEDs must be animated. If it remains frozen, or if no LED lights, then the CPU board does not start.

Module with LEDs


This achievement is available in our shop.


Last update of this page: August 7th, 2018

French Tech


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