(Topic ID: 182247)

bally SS lamp driver board circuitry- with bonus Altek question

By rufessor

7 years ago

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Latest reply 7 years ago by zacaj
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This is a complicated question- I suppose.

I have a Globetrotters on tour. Bally 1979 SS

It's all incandescent and looks amazing. Lamps fade beautifully on and off as a nice glowing piece of metal should. I am considering changing to LED for some more saturated colors on the inserts and to reduce heating. I would love to find an LED OCD type of solution with a lamp driver board that dims the LEDs to emulate incandescent behavior.

My understanding of the Bally lamp matrix is incomplete and hopefully evolving based upon some help here- so correct me as needed. Here is what I think is happening.

The lamp matrix runs off 18v but the lamps see much less because the circuitry switches on and off quickly- however- I don't think this switching rate is variable at an individual lamp level- thus I conclude the lamps are not programmed to dim- but I swear my eyes tell me they are programmed to dim because it looks so good with Incandescent.

Corrections?

Bonus-
Does the Altek ultimate lamp driver board use any type of dimming circuitry for the LEDs to emulate the fade of an incandescent? strangely I cannot find any information on this- after an admittedly cursory look that included the Altek manufacturer pages etc and a bit of google.

Ballys don't have a lamp matrix, and the lamps run off of 5.4VDC. Your description matches williams games with a matrix. Ballys have individual SCRs for each lamp that send the full 5.4VDC through when turned on. I'm not sure if they've got any analog effect (eg, they don't turn on fully at once), but I doubt it's much. Even williams games have a pretty good fade with incandescents, and before late system 6-system 7 they definitely weren't doing any fading in the software.

By my understanding, the LED OCD boards basically work by just reading the state of the lights from the original lamp matrix and then applying PWM based smoothing. This would also be possible with ballys technically, but since they've got 60 distinct lamps (and thus 60 distinct data lines), an extra board in the middle wouldn't really work, you'd have to redesign and replace the lamp board. The alltek lamp board doesn't do anything like that, though. It works by the same exact logic as the original, it just has newer, more efficient versions of the same components. The smoothing would pretty much require a live CPU on the board.

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