Wonky Crystal Castles Trackball- even with new Trackball

nerdygrrl

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Wonky Crystal Castles Trackball- even with new Trackball

I picked up a Crystal Castles that had a rough trackball. When I tested it everything worked fine, it was just rough. I bought a new roller and bearing kit, but that just made things worse. When I reinstalled everything, it was like Bentley Bear had a good o'l hit of meth and was all over the place. Sometimes he would be fine and other times he would move in the opposite direction or not at all.

I figured, I did not put the track assembly back correctly or I had bent something during my rebuild so I went out and bought an NOS trackball. I threw it in there and it is doing the same thing.

Any thoughts? I am not 100% familiar with how these trackball systems work. Do I need to align the optics with the optic PCB's?
 
I had a similar problem with a Centipede board. Unfortunately, it sounds like the problem is likely to be in the game board itself. The good news is that Atari schematics are usually pretty well organized. If it's like Centipede, there should be a trackball control section in the schematic package. The problem with my board ended up being a bad resistor.

I'll go see if I can find some CC schematics to see if I can offer assistance. Are you comfortable with soldering parts?
 
Ok, take a look here:

http://arcarc.xmission.com/PDF_Arca...stles/Crystal_Castles_SP-241_2nd_Printing.pdf

PDF Page 17 shows the schematic for the track ball circuit. Notice there is support for 2 trackballs (usually for cocktails). If your machine is upright, then concentrate on the trackball circuit 1 (HC1, HD1, VC1, VD1). If you can tell from the game if the problem seems to be more related to horizontal or vertical controls, you can further narrow it down (HC1 and HD1 are horizontal, VC1 and VD1 are vertical).

I would start the focus at resistors R88, R89, R90, and R91, and the capacitors C18, C19, C20, and C21.

Some may consider changing all these parts as "shotgun repair", but these parts are cheap, and you can usually find them at RadioShack.

The problem could also possibly be in the LETA chip, but that's not going to be an easy chip to replace (LETA is an Atari custom trackball controller, and it's difficult to find). I would say that it is more likely to be a problem resistor or capacitor though.

Good luck and let us know if you make any progress!
 
Ok, take a look here:

http://arcarc.xmission.com/PDF_Arca...stles/Crystal_Castles_SP-241_2nd_Printing.pdf

PDF Page 17 shows the schematic for the track ball circuit. Notice there is support for 2 trackballs (usually for cocktails). If your machine is upright, then concentrate on the trackball circuit 1 (HC1, HD1, VC1, VD1). If you can tell from the game if the problem seems to be more related to horizontal or vertical controls, you can further narrow it down (HC1 and HD1 are horizontal, VC1 and VD1 are vertical).

I would start the focus at resistors R88, R89, R90, and R91, and the capacitors C18, C19, C20, and C21.

Some may consider changing all these parts as "shotgun repair", but these parts are cheap, and you can usually find them at RadioShack.

The problem could also possibly be in the LETA chip, but that's not going to be an easy chip to replace (LETA is an Atari custom trackball controller, and it's difficult to find). I would say that it is more likely to be a problem resistor or capacitor though.

Good luck and let us know if you make any progress!

Thank you for the input. I will test the board out in another cab.

I will say it was working ok prior to me rebuilding the trackball.
 
Thank you for the input. I will test the board out in another cab.

I will say it was working ok prior to me rebuilding the trackball.

Check to make sure you reconnected the two optics boards correctly. If you got their positions swapped it will cause Bentley Bear to move in the wrong direction.

Also, you mentioned buying a new trackball. I did the same for my Crystal Castles, buying a new trackball assembly from Arcade Shop, and I had a similar problem upon installation. One axis was correct (up/down) but left/right was backwards. It turned out that it was wired incorrectly at the factory. Had to swap a couple of wire positions to fix it.

If the directions of the movements are correct and Bentley Bear sometimes does not respond at all, it could be a bad optic board. You can get new replacements of those, but they should be fine if you bought a new trackball or one that was truly NOS.
 
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Sometimes Bentley is ok and other times he is all over the place. I am guessing the PCB orientation is correct, but perhaps I have a bum optics board. I totally regret rebuilding the trackball I should have just left it.

I guess my best bet is to test the board and then go from there.
 
Any thoughts? I am not 100% familiar with how these trackball systems work. Do I need to align the optics with the optic PCB's?
It's pretty easy. Spinners and trackballs can be described as a quadrature encoder. The 2 optos are spaced slightly apart to read the blocked/open area of the wheel and create two signals. For example:

Code:
  A-  B
off-off (both in a gap)
off- on (one in a gap, the other blocked)
 on- on (both blocked)
 on-off (one blocked, the other in a gap)
off-off (both in a gap)
off- on
....and so on

You can tell direction based on if A leads B, or A lags B. Meaning if the current state is off-off what happens next? If it's off-on you're turning one direction. If it's on-off you're turning the other direction.

You could put your oscilloscope on the lines and see if the pattern looks reasonable. But most of the time if it work intermittently, just swap the optos with an alcohol soaked qtip to clean. If it doesn't work at all then use DMM or oscilloscope to check that the optos toggle at all, check wiring, check pcb inputs.

EDIT: See wikipedia (here) for a decent visualization of that encoding. The little black opto assemblies used on those boards are simple photo-transmitter and photo-receiver pairs. Just block/unblock it to get it to switch. They're cheap as hell and common, so if in doubt just replace the component.
 
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+1 for bad optics board. I've had this exact problem more than a few times and every time it was the optics board that was the culprit. Eventually the wonky axis will stop working completely, you just caught it on the way out.
 
Nerdy bought the nos trackball from me, it's an Atari 3".. As for bad Optic pcbs, I tested it before selling on another game.. But who knows what can happen from here to there..

Nerdy, I've got 50+ optic pcbs and more harnesses.. I'd be more than happy to run them over or drop some in the mail.. I want to check that chassis anyway so I should just run over..

Sorry to hear your last few buys from me didn't go well :(
 
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