Big Bang Bar

[Kerry Richard]

I'm working on a Big Bang Bar right now with a strange lighting
problem. All of the lights seem to pulse, for lack of a better word.
In test, when all of the lights are supposed to be on solid, they
quickly pulse from normal brightness to dim, almost like the lamp
matrix is being swept through, but at too slow of a rate. Another
strange thing is that even when all lights should be turned off, the
filament on every one of them can be seen VERY faintly pulsing.
I started by checking the +20V lines for the matrix, and everything is
fine (ripple is ~40mV). I also disconnected all lamps from the matrix
and hooked up a single bulb directly to the headers and it still
pulsed. I'm thinking that I have some kind of logic problem that is
inadvertently enabling the lamp matrix. I believe that I have the
skills and tools to troubleshoot this, but I don't have a schematic,
which is really holding me back.
If anybody has any ideas, or better yet a schematic, I would love to
hear from you!
Thanks!
-Jason Richard

Kerry Richard #111

[The Other Guy]

What we have here, is failure to comunicate...

What you are seeing happens all the time with the CAPCOM light matrix system. All the matrix bulbs are pulsed to keep them not quite illuminated, that is, warmmed up (if you will). Sometimes they get warm enough for you to notice...

There are times when a short in the wiring will cause one or more bulbs (other than the one meant to be on) to glow from half bright to almost full bright. This is ususlly a diode on backwards, the wires swapped on a lamp base or some solder bridging a lamp base...

If the effects you are seeing can be seen in a normally lighted room during game play, you may have a real problem. If you have to look to see this effect, you are probably one of the few to have noticed...
The first time I saw this was while troubleshoot with the room lights off, it stands out like a sore thumb!

Let me know...
TOG
_________________
"BBB 77"

[Kerry Richard]

TOG,
This is Kerry Richard's son, Jason Richard. I am the one attempting to trouble shoot this problem.

Anyway, I appreciate your advice, but unfortunately I don't think that is the problem. I have heard from others that Capcom games pulse the filament to keep it "warm", so I'm not so concerned about that anymore. The problem with the lights pulsing, though, is still present. It is very clearly visible in natural room light, so it is not just my eyes. I have tried a few different things during my troubleshooting, so I do have some things to narrow down the search. You mentioned that it could be a backwards diode, or short in the harness. Unfortunately this can't be the problem. First of all, there are two separate lamp matrices in the game, and the problem is present on both. Obviously the chance of the same fault on both is very slim. To further negate this, I have disconnected both matrices from the driver board and connected a single bulb directly to the headers. Even with this configuration, the single bulb still clearly showed the problem.

I intend to investigate the issue further this weekend. I think I'm going to borrow a scope and look for a chip enable issue. If you have any other ideas in the mean time I would love to hear them!
Thanks!
-Jason Richard

[The Other Guy]

Sorry I couldn't be of any help.
I would be very interested in your findings!
_________________
"BBB 77"

[just plain rob]

Any chance you could make a natural-lighting video of this?
I wonder what it is you see after reading this...

[blubboman]

I know my Pinball Magic does this when I test for lamps although it's very subtle. I'll try to get a crappy video off my camera of the bulbs pulsing this weekend. I can't recall if Airborne does it also but I assume so.
Dan

[blubboman]

Well - I tried to get a video. My digital camera doesn't really have the frame rate capability so you couldn't really see the flashing. Also, since the lamps are all incandescent, they definitely don't go off all the way when pulsing like that. My camera just couldn't pick it up.
Dan