(Topic ID: 119135)

alien poker switch matrix problem

By heypat

4 years ago

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  • 8 posts
  • 4 Pinsiders participating
  • Latest reply 4 years ago by winteriscoming
  • Topic is favorited by 1 Pinsider


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#1 4 years ago

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.


#2 4 years ago

First step is to isolate the issue to the pcb or to the wiring / pf. This should be easy to straighten out.

Pull the column and row plug off the board.
Game in test mode.
Use an alligator clip to close switches right on the connector plugs. Use the switch matrix diagram / schematic to find the pins.
If you find nothing reads on your bad row, the issue is on your driver board. If it does read on the bad row, the problem is on the wiring to the PF.

If you find the issue is on the driver board, check the connector pin solder joint. Otherwise we need to test the rows. The rows are the "read". So there is a 4049 chip that has a pull up resistor waiting to get pulled down. Look for the input and output of this 4049 gate to change state when closing the switch. Compare it to other rows if you are unsure.

If the 4049 tests good. Need to pull the driver board, go to the bench with test rom and make sure the associated PIA leg can change state.

When someone shorts coil voltage to a switch line, it will blow out the 4049 or 7406(column drive) chip on the driver board. That happens a lot.

#3 4 years ago

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.


Thanks again for your help !

#4 4 years ago

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

#5 4 years ago

Glad you figured it out. Sorry to be all Johny-come-lately to your thread. Let me know if you need any pics from mine.

For reference for anyone reading this in the future, Alien Poker's drop target horseshoe switches can be successfully replaced with standard leaf switches for a much more reliable setup. I think for some games of this era there might be an issue where the switch will constantly score if it's activated (It's been a while since I looked at one, but maybe horseshoe switches just momentarily make contact on the way down?), so this may not be an option for all older Williams games, but AP doesn't have that issue. The thing is that the stock drop-target bank doesn't have mounting points for leaf switches, so a different Williams 5-bank drop-target bank (or at least parts from it) is needed such as one from Jungle Lord.

#6 4 years ago

By the way, since it's been so long since I swapped in the Jungle Lord 5-bank drop target assembly into Alien Poker, I don't recall if the JL bank came with individually controlled coils for each drop target. You'd need to wire those up, too, or keep the ones from AP so that it can shoot each target back up individually like it's supposed to do.

#7 4 years ago

Glad you fixed the drop targets, now if we could only get some repo backglasses for theses Alien Pokers.

#8 4 years ago
Quoted from Razor:

now if we could only get some repo backglasses for theses Alien Pokers.

PPS has that power. I haven't seen where Rick of PPS has mentioned whether or not they have found the original screens for the AP backglass. Based on some posts by Stu of CPR, CPR already had someone working on it, but it's probably in limbo due to the PPS buyout of IPB stock which included a lot of original Williams screens.

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