Crazy Flipper Fingers

One of the opto signals on my Freddy is registering as constantly open. I pulled the emitter and detector from their posts, but left them connected to the driver board. I shined a flashlight into the detector, and it registered correctly. I then pulled out one of the working sets of opto's on the machine, and put them in the place of the "faulty" ones. Same result, they didn't work, but the detector would register if I shined a flashlight on it. I put them back in their original spot, and they worked fine. I'm not good at the electronic stuff, but I'm pretty sure that I have continuity from the opto driver board to the emitter and detector.

Is this a problem with the opto driver board? 3 of the 4 optos work fine. When I put known working optos in the problem spot, they do not work. As I stated, if I shine light into the detector, it works properly. Has anyone dealt with this issue before?

I've never worked on a Gottlieb System 3 so I'm probably not the best person to offer advice, but here are some simple things you can check.

Take look to make sure the solder joints of the transmitter LED haven't cracked. If so, reflow the solder. You could also try replacing the LED, as they're a common failure point:

http://www.greatplainselectronics.com/s ... ype=&scat=

Might even be able to find this part at RadioShack.

You can also use your cell phone camera (or most any digital camera) to see whether or not the opto transmitter is functioning. Simply point the camera at the transmitter and you should see it glowing on the LCD screen if it's working correctly.