Arcade Collecting > Pinball
I finally got a pin...RESTORED AND LOVING IT.
shardian:
We've been playing the pin every night since it was fixed. My wife is actually encouraging me to go ahead and restore the playfield. She even made a trip to the craft store to pick out acrylic paints for touch-ups. I figure I'll leave it on the market for 2 weeks, and if it doesn't sell I will go ahead and shop it out.
Have I mentioned that my wife rules? ;D
shardian:
I finally took the time to 'decode' the switch matrix last night. As I've discussed earlier, only 2 of the 4 top rollovers work, and that limits several other playfield features. They were the only switches I thought weren't functioning. Well it turns out that the "C" rollovers are actually the same switch input. The other rollovers are on the same return line, so that couldn't be a problem. The strobe line is where things get interesting. The shared strobe switches are a red drop target, a white drop target, and a rollover button. Since the sound hardly ever works and I get mechanical feedback when scoring a target, I've never really noticed if these other switches scored or not. It was too late to test out last night when I learned this, but I can pretty much guarantee that they will not score. This means I just need to check the pin and trace the wire from one CPU connector to find the problem.
Pins may be a royal PITA sometimes, but the feeling of accomplishment when solving a problem is very addictive. ;D
shardian:
Ok, I have an electronics question for the Guru's.
The strobe line is definitely the culprit. I continuity tested everything, and it is good all the way thru the cpu pin. The way the sys1 is wired is that all switches run to a diode bank on the bottom of the playfield. All the diodes for each return then tie together and run 1 wire to the cpu connector. I was really hoping I would find a break in continuity. Since I didn't I am stuck.
The only other possibilities are the diodes or the cpu board. Could a bad diode cause the whole row to stop responding? Wouldn't it read as a stuck switch?
If that is not the culprit, then I am left with the cpu board. There is a 7404 chip that the switch matrix feeds thru that can go bad. Can a bad 7404 chip result in a single strobe going bad?? I have a probe and am willing to go thru the hassle of using it, but I am just curious if a single dead strobe line would be caused by the chip.
shardian:
Well in that case I will clip/check all the diodes on that line tonight. IIRC, in a jamb you can use a 1n4004 to replace those, right?
shardian:
Good news and bad news.
The good news is that my probe definitely shows the problem is that strobe 0 is not functional on the 7404 controlling chip. The bad news is that neither input for the strobe is flashing - that means one of the spider chips are bad. I misinterpreted the results to think the 7404 was bad and I was home free. I wasted over an hour scavenging another 7404 from a dead board, and almost finished desoldering the 'dead' chip before the reality dawned on me.
All I can say is MOTHER ---smurf---!!!!ELEVENTY1
At least the board is 98% functional though. I tried my second bench booting board and there is something wrong with it. It boots in the game to 000000 displays at the proper time, but does not fire the solenoids. It the flashes a 't' in each display every few seconds after that - I can't coin up or start a game. I haven't read about that, any ideas jim. At least the z8 7404 was working... ;D
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