So I have a Classic Sport Air Hockey table a just picked up and the scoreboard isn't working. I found the following thread... https://forum.allaboutcircuits.com/...-display-proble-air-hockey-scoreboard.120942/

I have another thread where I was looking for replacement transistors, so I hope I am not breaking any rules by posting a new thread. I felt this was a slightly different issue.

I replaced the transistors for segments D&E and now they all light up when I first turn it on, but when only certain ones should be lit up, most of the rest are lit up dimly, so you still cannot tell the score.

Please bear with me when giving advice on what to check, I will be asking how. I am not as well versed as most of you are and I can muddle my way through, but will require a lot of guidance.

I appreciate any help in advance and will do my best to follow your directions.

As you can see in some of the pictures when the time should be 10 minutes segments D&E are lit up still, when it should be 20 minutes it is fine, and 30 minutes E is still lit up. I notice that with the score that D&E remain lit up.

As I am typing this, I am starting to wonder about an issue with what tells D&E to light up. Since those where the ones that didn't light up in the first place, I tested the transistors while installed on the board and they appeared to be faulty, so I replaced them, but now they will not turn off. So I am thinking that would be a good place to start.

Thanks,
Karl

 

I was just checking, and when I was checking power on the circuit board the other night, I was getting 13.5 volts on 2 pins. I just happened to look at the power adapter that came with the air hockey table tonight and I see it's output is supposed to be 7.5VDC. I am getting 14.3VDC out of it. I ordered a replacement one from Amazon and "should" get it by tomorrow. I am hoping that is the problem, that I am getting too much voltage and that is causing the malfunction. I just hope I didn't damage anything.

 

So the replacement power adapter came in and it didn't solve anything. I still get some of the same malfunctions and what is weird also is the f segment just on the first digit of clock doesn't always light up, except right at start up.