Goblins Coin Up Problem - New New Evidence!

Pixel8Arcade

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I'm having a strange problem with my Ghosts N Goblins machine. After speaking with a technician he advised me it could be an issue with my "interface chip" on the pcb.

Can anyone point out exactly what chip that is?
 

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I'm having a strange problem with my Ghosts N Goblins machine. After speaking with a technician he advised me it could be an issue with my "interface chip" on the pcb.

Can anyone point out exactly what chip that is?

Doubt anyone can help from that description - what is the actual problem?

Only thing that comes to mind for 'interface' would be the chips reading the control inputs, but if that you'd have to narrow down what input exactly was wrong as multiple chips are involved.
 
I'm having a problem with coining up and it's not the microswitch or wiring from the coin door. I was told by an arcade tech that I should check the "interface chip". Hoping someone can point it out on the photo I uploaded.
 
Ok, so it is input. Do other inputs work, or is it just coins?

For coins the likely problem is the chip at location 8A - it should say 74ls367. There is also a chance it's the chip at 3A (LS138) or the resistor pack marked RC5.
 
Thanks for the info tendril. All other inputs are fine, just coin is being wonky. sometimes it works, sometimes it doesn't.
 
I'm having a problem with coining up and it's not the microswitch or wiring from the coin door. I was told by an arcade tech that I should check the "interface chip". Hoping someone can point it out on the photo I uploaded.

Did you try to manually coin up by gnd'ing the coin pin/pad on the pcb? If not, you might want try this first.
 
Short coin2 V | 18 coin1 to GND, to see if the game coins up.

So you can check if it's the PCB or the harness.
 
I never tried that jacklick. How exactly would I do that? And what would it tell me?

I am no expert but my thought is...
It would truly tell you if the problem is at the board or not by eliminating all other factors. If it coins up fine and consistently by briefly touching the card edge fingers/pads 18 to 19 or V to W, then you don't have a pcb issue.

If it does, I would then review the schematic and see of the coin gnd is supposed and does have continuity with logic gnd. You could have a bad gnd but if it coins up sometimes I would not believe it to be a pcb issue.

http://www.arcade-museum.com/pinouts-game/7938.html
 
Short coin2 V | 18 coin1 to GND, to see if the game coins up.

So you can check if it's the PCB or the harness.


I don't want to cause any damage to the pcb so could you describe the best way to short pin out 18 with the GRD. Do I just touch my multimeter probes to both at the same time and see what happens with the game turned on? Do I keep the edge connector in place or disconnect it?
 
I don't want to cause any damage to the pcb so could you describe the best way to short pin out 18 with the GRD. Do I just touch my multimeter probes to both at the same time and see what happens with the game turned on? Do I keep the edge connector in place or disconnect it?

There is nothing close to pin 18 that would do any harm.. I have my G&G on the bench and there is a capacitor with its negative lead facing the card edge. I would attach a mini clip to that and then just touch the other side the exposed pcb pad/finger or use a probe and go into the harness on wire side.

It sounds daunting but it isn't. Either way you can use the negative lead of capacitor so you only have worry about one end of the jumper.
 
Thanks jacklick. PCB repair is not my thing, but I actually understood what you instructed me to do.

My GNG is on location so I will try this next time I go over there.
 
I have not had a chance to manually coin up the game yet. However, I have a new piece of evidence that maybe someone can decipher.

The machine the other night started coining up on its own. In fact it wouldn't stop. It was giving itself a credit every half second and after a few hours it had accumulated over 23,000 credits - no lie.

So does this new odd ball behaviour point to anything specific?
 
Ghosts escaped the game and are running loose? I am just guessing as I haven't even looked at schematic but something is connecting the coin line to gnd, a short of some sort, ttl chip going bad. Could still be an external factor but likely not.
 
This sounds more like a capacitor problem on one of the coin inputs. Each input will have a pull up resistor and a capacitor. The values of them are the same for each input. One end of the resistors will be connected to the input while the other end of the resistors are connected together and to 5 volts. One end of the capacitors will connect to the inputs and the other ends will be connected together and to ground.

To know which one you will need the schematics and find them. They will be close to the edge connector and before the input pin on the IC's.
 
There is nothing close to pin 18 that would do any harm.. I have my G&G on the bench and there is a capacitor with its negative lead facing the card edge. I would attach a mini clip to that and then just touch the other side the exposed pcb pad/finger or use a probe and go into the harness on wire side.

It sounds daunting but it isn't. Either way you can use the negative lead of capacitor so you only have worry about one end of the jumper.

So tonight I was able to connect an alligator clip to the negative lead of the cap facing the card edge and touch the other end to the exposed pcb pad of pin 18 and nothing happened.

What does this mean?
 
The culprit is the custom resistor/capacitor array @C5 or the 74LS367 @8A, you should determine this with a logic probe and check where signal doesn't properly toggle from HIGH to LOW when you press the button (or maybe it's just stuck HIGH).Attached schematics snippet:
 

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The culprit is the custom resistor/capacitor array @C5 or the 74LS367 @8A, you should determine this with a logic probe and check where signal doesn't properly toggle from HIGH to LOW when you press the button (or maybe it's just stuck HIGH).Attached schematics snippet:

Does everyone agree with this assessment or could there be another cause?
 
Does everyone agree with this assessment or could there be another cause?

The problem is that you want the ready solution.I'm sure (and schematics speaks clear) the problem is in the custom resistor/capacitor array or the 74LS367 after this.But, you know, I'm saying this remotely so cooperation is needed from you too.Do you have a logic probe to check what I said?
 
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