In my post on Wednesday, I mentioned a few things that weren’t working properly on my recently acquired Elevator Action game. The joystick did not respond when pushed up, the player 1 start button was not working and the second coin slot was not registering credits. I decided to focus much of my initial efforts tackling the up directional on the joystick as the game was almost impossible to play without it working.
I like to start my troubleshooting at the source and work backwards, so I began taking some readings on the joystick with my voltmeter. I took my first set of readings on the joystick leaf switches, measuring the voltages for left, right, down and up. Left, right and down all measured a consistent 4.8 volts, while up produced a reading of 0. The control panel and all of it’s switches and buttons plug into the main wiring harness with a 15 pin molex connector. I took my next set of readings on the wiring harness side of this 15 pin molex connector. Again, the joystick up directional measured 0.
Between the game board and the control panel is a filter board. I’m not really sure of it’s purpose but my guess is that it cleans the signals coming off of the main pcb before sending them out to various components of the cabinet and vice versa. The filter board is made up of 11 headers, each with about 14 pins. I measured the voltage of header R16 (one of two), pin 5 which is the next logical step between the molex connector and control panel. Again, the reading was 0. I went to the other R16 header, pin 5, and again received a 0 reading. I then decided to test the continuity between the two R16 headers and found several cold solder joints. Instead of just repairing the few I found, I de-soldered all of the header pins and reflowed the solder to all of them. I then tested all 11 headers again and found no continuity problems.
I still wasn’t getting any voltage reading on the up directional pins on header R16 so I proceeded back to the game board. I took my next set of readings directly on the edge connector finger board of the game board. The up directional is controlled by the 13th pin on the solder side. Taking my reading directly off the edge connector finger board produced a steady reading of about 5.0 volts for up. This told me my problem was between the edge connector and the filter board. The only logical conclusion was the edge connector was not making good contact with the finger board of the PCB. I took a small flat head screwdriver and bent every connector pin down towards the finger board to ensure that good contact was being made. Like magic, I all of the sudden had good voltages at the filter board, at the molex connector and at the joystick.
I started a new game and everything that was previously not working started working. The second coin slot was now registering credits, the player 1 start button worked and most importantly, the up directional of the joystick was working! I know the up directional was fixed by the bending the pins down on the edge connector. The other two could have been fixed by repairing the cold solder joints. I’ll never know. While my description probably sucks, it’s really not that difficult to troubleshoot basic problems with games. Once you get into the circuit boards, it gets a bit more difficult but the key is to understand the flow of everything and have a good set of schematics to work from and study.