Picked up a dead alien poker recently, I finally got it working ( a big thanks to Barkandl for the 5101 Ram) but it has an issue with the drop target switches not reading, everything in row 2 of the switch matrix is dead. the drop targets were in about 20 pieces when i bought the machine so i replaced the whole bank with one from a jungle lord thanks to a heads up from Winteriscoming. He is using this in his alien poker with no problems. I double checked all of the wires for every switch on row 2 of the matrix from the switch to the connector on the board and all are good. I also checked all of the diodes and they are all good, I did find one that was bad and replaced it.

next i pulled 2j2 and checked for pulsing with a logic probe and all pins were pulsing. (which I'm told is good)

then i pulled 2j2 and 2j3 and checked the pins on 2j3 and there was no pulsing (which i am told is good)

then with 2j2 and 2j3 connected i put my logic probe on pin 8 (for row 2 of the matrix) and started making the switches in row 2. I am told i should see a pulse every time a switch is made. I did not see any pulses when i made any of the switches in row 2 of the switch matrix.

so i know the whole row has a problem, i just do not know where to look next. I cannot find anything that points me to a specific component to test.

Any suggestions.

Thanks!

I put the board in test mode as suggested and checked at the board and was shocked to see all is working well on the board end. Everything in Row 2 of the switch matrix including the 5 drop target switches were read at the board. You indicated this means the problem is on the play field. The question is what am i looking for on the play field? i already verified the wiring from every switch back to the board and there is conductivity (no broken wires) i checked all of the diodes at the switches and they were fine. After I tested at the board I also replaced the diodes just in case.

Checking the switches on the board did take quite a bit of time as the right digits on the credit board work intermittently. I already tried the simple stuff, swapped ribbon cables, cleaned all pins (yes they were green) and re soldered the pins on the display board. I will add this to list of things to repair.

I also found that all of the lights in column 5 of the lamp matrix are not working. Another thing to add to the list. Looks like it could be Q71. I will check it next time I pull the driver board.

I figured I would mention those issues in the event they could possibly be related.

I added a photo of the bottom of the drop target that shows the wiring.

IMG_2629.jpg

Thanks again for your help !

well, I figured the drop bank issue out. Diodes were backwards. I bought this off ebay and just left the diodes as they were as the looked like the originals. I put new ones in today in the same orientation because I was stumped. I checked the old diodes to make sure they were not bad but never checked them with the switch. But when I used the meter to check the switches they were clearly backwards. And every photo i could find on line of a leaf switch on a drop target showed the diodes just like the photo above, which had me second guessing myself, even after i checked it with the meter.

well on to column 5 of the lamp matrix and then the display, with me luck !

Barakandl thanks again for the help, you certainly kept me on they right track