These pics show my home made board test jig I built to test bally and gottlieb driver boards and displays. With this I can fully test both bally AND gottlieb 6 digit displays, bally lamp driver boards and gottlieb sys 1 driver boards. The top rows of LEDs connect to each output of a stern/bally lamp board, and the bottom rows are for the gottlied sys 1 driver board, each LED goes to an output driver transistor or SCR. The gold strip in the middle has the edge conector for the sys1 board behind it. Each LED is labeled with the board reference number for the output device its connected to.

Anyway for the bally/stern board, an internal binary counter drives the ic’s on the driver board, turning each output on one at a time in each of the four banks of leds, one bank for each decoder ic and its output devices on the driver board. the fore red switches at the top let me blank each bank of leds to test the decoder ic’s and the output SCRs. The 5th switch (strobe) lets me stop the decoders on a particular output in the four decoders, as can be seen in the 2nd and 3rd pics, thus its telling me Q43 on the driver board isn’t switching.

Last pic shows the output working after I replaced the SCR Q43. the board was then ready to go back into the machine.