Grand Slam
Bally, 1983Am I the only person here that owns one of these boards? A search of all tech found nothing.
I've got some bulbs out and was looking for some more information. There are two lamps listed for the output of each SCR: "phase" A (where phase is a zero with a slash through it) and phase B, how does that work?
Looks like this might be a hard board to fix. The 4 to 16 demultiplexing chips seem pretty hard to find.
Thanks
Quoted from LTG:Will this work ?
http://www.allteksystems.com/products-mpu-replacements.html#lamp
LTG : )
It's a combo board, not just a lamp board. It's similar to what baby pacman has.
Quoted from mcbPalisade:Looks like this might be a hard board to fix. The 4 to 16 demultiplexing chips seem pretty hard to find.
Where have you looked? GPE, bigdaddy, mouser, jameco?
I doubt they are impssible to find.
Quoted from mcbPalisade:There are two lamps listed for the output of each SCR: "phase" A (where phase is a zero with a slash through it) and phase B, how does that work?
Baby pacman drives two lamps per SCR as well. If the grand slam manual doesn't have a theory of operation section, baby pacman has some info.
The schematics should also give you some info.
Usually, when an SCR fails, two lamps don't work.
I really want to fix what I have. The SCRs are available and cheap, guess I'll start there.
It is somewhat difficult to figure out which lamp the schematic is talking about, but I suppose I can always trace wires.
The CPU works fine so I don't really want to replace it.
Winter is almost here, need something to work on...
Quoted from mcbPalisade:Am I the only person here that owns one of these boards? A search of all tech found nothing.
I've got some bulbs out and was looking for some more information. There are two lamps listed for the output of each SCR: "phase" A (where phase is a zero with a slash through it) and phase B, how does that work?
Looks like this might be a hard board to fix. The 4 to 16 demultiplexing chips seem pretty hard to find.
Thanks
The lamp circuit on the driver board can be diagnosed the same way you would do the normal lamp board.
The decoders (4514) are pretty robust in this circuit. Very rarely fail. Your problem is probably in the connectors and SCRs.
Multiphasing is done with alternating current and diodes at the lamps which allows for one SCR (provides ground return) to blink two lamps individually.
Ah, that explains why "SCR Return" is a separate line.
And the problem could be in the lamp diodes. I thought those were used as snubbing diodes, but since lamps aren't inductive there would be no need for those.
Thanks, good tips. I didn't see anything in Baby Pac-Man theory of operation that explained this.
I was able to order 100 TO-92 SCRs (MCR100-3G) from Arrow electronics for $0.14 each so I'll be replacing them all.
From what I can tell the demultiplexers are OK and it must be the SCRs. 12 out of 30 bulb pairs are out.
Quoted from LTG:Will this work ?
http://www.allteksystems.com/products-mpu-replacements.html#lamp
LTG : )
I wrote this company and this was their reply:
> None, my Solenoid and lamp board will not work in this game. Only my MPU board will work.
Quoted from mcbPalisade:I was able to order 100 TO-92 SCRs (MCR100-3G) from Arrow electronics for $0.14 each so I'll be replacing them all.
From what I can tell the demultiplexers are OK and it must be the SCRs. 12 out of 30 bulb pairs are out.
You don't need to unncessarily shotgun the board. Just look at the schematics for which each SCRs drive which lamps and only replace the bad ones.
Quoted from barakandl:Multiphasing is done with alternating current and diodes at the lamps which allows for one SCR (provides ground return) to blink two lamps individually.
So there must be some part of the circuit that detects if the AC is in the positive or negative half of the cycle. Anyone care to point this out so I can see how that works?
Also I would imagine that this value would be used to control the 4514 Inhibit input in a real-time fashion.
Quoted from mcbPalisade:So there must be some part of the circuit that detects if the AC is in the positive or negative half of the cycle. Anyone care to point this out so I can see how that works?
Also I would imagine that this value would be used to control the 4514 Inhibit input in a real-time fashion.
The CPU has a "zero cross detection" circuit which identifies every time the transformer AC voltages "crosses zero" and also the feature lamps multi phase crosses zero. Since the line cord AC alternates at known rate, 120hz, they use it as a timer to trigger an interrupt to the CPU to run the software that updates lamps, switches, solenoids. The multiphase lamps are on a center tap transformer. So there +6vac to ground on one side and -6vac to ground on the other. The SCR makes the 0v or ground point. So when the AC is swung to negative 6v and the SCR is turned on, only the lamp connected to the -6vac and scr lights. The other lamp between the same scr and +6vac does not light (diodes on every lamp only lets the AC to only go one way).
I'm in the proces of creating a Tech Chart for Grand Slam.
Here is a pdf file of all teh controlled lamps.
The first page is alphabeticaly and the second page is sorted on the scr.
Maybe this helps you find the right scr to replace.
Peter
Very handy, I thank you for doing this.
I took a picture of my schematic (I can't read the ones on IPDB with that black background) and used Photoshop to make the background white so it didn't use up all my toner. It shows some of the same info from the connectors perspective.
That is it! One difference I notice is that you are missing one relay output setup in the lower right. Mine is completely populated.
Quoted from mcbPalisade:Very handy, I thank you for doing this.
I took a picture of my schematic (I can't read the ones on IPDB with that black background) and used Photoshop to make the background white so it didn't use up all my toner. It shows some of the same info from the connectors perspective.
Well, that's easy enough to add.
Here is a pdf with the lamps sorted on description, scr and connector.
Peter
Now I see what you mean.
He is missing one transistor, thus missing one output.
Probably needs some repair, as Q41 is used in both Goldball (knocker) and Grand Slam (outhole).
The only two games known to use the AS-2518-147 board.
Quoted from Inkochnito:Probably needs some repair, as Q41 is used in both Goldball (knocker) and Grand Slam (outhole).
The only two games known to use the AS-2518-147 board.
Lovely, well the good news is it mostly works. And with all new SCRs that are much beefier it should run until the paint is ripped off the playfield.
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