1990 Bally Gameshow flasher problem

alexanr1

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I recently purchased a Bally Gameshow and thought it had a few flashers burnt out. When I went to replace them I ran into a problem. The flashers in question have both a playfield flasher and a backbox flasher. When I only have 1 of the 2 sockets with bulbs in them, the single flasher works. When I put two bulbs in, both bulbs barely flash, like they don't have enough power. Has anyone ever seen this before? Is it possible that the transistor works under a lesser resistance and with a greater resistance it has some sort of power issue? All four that operate this way are acting the same way. Transistors Q23, Q24, Q25 and Q32. Seeing all four made me think it's not the individual transistors but something else. Any help is appreciated.

-Rich
 
You could always put LED flashers in and there will be no brightness issues. I do believe at least
 
Is that in game play or during test? I've seen games that only " blink " the flashers in test but "flash" them during a game.
 
Both, game play and test.
 
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Let's rule out the obvious. Are you using #89 bulbs? Also, how about Q33 Top Center Lane/ Insert Teeth Flasher? That's another double bulb setup. Does that have the same problem?
 
Good question. I need to double check the center lane flasher. They are definitely all 89 bulbs.
 
Cmndr - I checked and all double bulbs have the same problem. For kicks, I tried what Jrivelli suggested and to my surprise they work with LED flashers. I am wondering if I have some sort of volt/amp issue with the flasher circuit. Again, either bulb by itself works. With the LED's they work as well. Is there a relay, I am not seeing that causes them to switch from playfield to backbox? Don't see it on the schematic, it looks like they are driven directly by the transistor.
 
Is there a relay, I am not seeing that causes them to switch from playfield to backbox? Don't see it on the schematic, it looks like they are driven directly by the transistor.

You are paritially correct. There is a relay you could check. It's fired by SOL12. That is the A/C select relay. Williams system 11 games ran out of "space" in the number of solenoids they could fire. So, they multiplexed them into and "A" circuit and a "C" circuit switched by a relay. If you have the manual page 1-38 explains this and gives the schematic. It looks like on the Aux Pwr Driver Board there is a relay "RLY1" (although the schematic is wrong, it says relay K1. K1 is on the main board and NOT the relay you want). RLY1, on the aux pwr board, should be the A/C select relay. It looks like all the problems you are having are on the C side of the ciruit. There are 2 - 2.5A fuses next to that relay, check those and the fuse holders first. Then in the diagnostics menu, go to the coil test. Press the button until you get to the A/C select solenoid. You'll hear and see it clicking. Sounds like it's a grounding issue to me, so if it's not the relay or the fuses check for cracked solder joints or burnt/loose connectors to this part of the circuit.
 
Correction: The fuses are not next to the relay. They are labled F2a and F2c. on the left of the aux board.
 
The relay switches fine. I checked it. Wasn't sure if there was a second Relay i wasn't aware of. It's odd that the lights that are for his teeth ( 2 bulbs) always seemed to work fine. Any single flasher bulb whether in the head or the playfield works fine (note I am removing the other bulb and doing a manual test) The issue is when two flasher bulbs (playfield and head) are fired. Again, the LED bulbs seem to not draw as much current and work. Appreciate the help so far, I know these are not easy issues to debug.
 
I double checked the relay, it seems to be operating fine. It seems like it has to be some voltage issue or some odd grounding issue. All of the flasher bulbs that have both a playfield and and head flasher have the same problem. Individually the each work fine (I take the bulb out of the playfield or the head and test). The odd thing is when I use an LED flasher they seem to work fine. I am assuming the LED flasher doesn't pull as many amps to fire it. I know this is an odd issue and I appreciate all of the help. Any thoughts on how to better isolate where the issue is coming from?
 
Remove F2A then jumper the "relay" sides of F2A and F2C together, now you have the "C side " solenoids only activated. Try tapping the metal tabs (collectors) of the suspect transistors to check the connections from the board to the lamps. The lamps should be real bright, don't hold the jumper on there! If that's good, using your schematic, take a jumper from 5 volts and tap the output pins of U19, and U20. The associated flash lamps should fire as you tap the output. Don't hold the wire on there to long, you might burn out the lamps . This will test the transistors. Like you said in your 1st post, it might be the transistors are getting weak. If they work good like this you could have IC issues. U19 and U20 could be failing and not sinking enough current to turn the pre-drive transistor on enough to get a good pulse from the output transistors. There are 7 pairs of flash lamps, do any others besides the teeth work fine?
 
Then it seems to be that the common element to the flashers with a problem is U20!!

ooops!! I looked again and U19 is still in there..
Do the associated solenoids fire strong? Some don't have a solenoid some do.
 
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U20 triggers the transistors, but would it effect the current if it is having issues? It's an AND gate, correct? I was assuming it either triggers or doesn't trigger the Q28, Q29, Q21, Q20 which drive Q33, Q25, Q32, Q24. We know it is triggering them because they do work with one bulb. Anything Incan do to diagnose 100% before I desolder an IC. They are a pain to desolder. :)
 
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Yep, sorry. No time tonight to mess with it. Will try tomorrow. Thx.
 
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