Burgertime coin up issue

hatrick

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I'm working on a Burgertime that will coin up once, then not again. Some times, if I switch it off for a minute, I can again coin up one game, then no more.
It's not the coin switches or wiring. When the issue happens, it appears that all the wires to the coin switches are shorted together.
I attempted to look at the schematics online to find out what logic chip may be causeing this, but I couldn't find a set that were clear enough.
Anyone know where a good scan of the schematics are, or what chip(s) on the pcb may cause this?

Thanks,
 
Sorry for ressurecting this old thread Dan but did you figure out what this was? Our BT is having the same issue.

I narrowed it down to a couple of chips on the pcb, but never ended up fixing it. We had a spare pcb, so I just swapped it and shelved the pcb with the coin up issue to tackle at a later date.

The copy of the schematics I have is crappy and hard to read, but I'd look at the 74LS02 at 7A or the 74LS74 at 13F. These are all on the sound I/O pcb.

**edit found a better copy of the schematic and confirmed the locations as 7A & 13F
 
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Thanks Dan. I'm going to pull the board this weekend and see if I have any luck, starting with those two spots. BTW I have the original schematics and manual if you ever need to borrow them.
 
Thanks Dan. I'm going to pull the board this weekend and see if I have any luck, starting with those two spots. BTW I have the original schematics and manual if you ever need to borrow them.

Let me know how it goes. If I remember correctly, our issue was with both coin -up circuits. I focused on those particular chips because they were used on both circuits. If yours is just an issue with one side, it may be another chip in the individual circuit.
 
You do know there is a software algorythm that looks at how long the coin switch is closed?

There was a Midway service bulletin issued years ago about the game locking up and it was because the coin switch was being held too long or moved too slowly. Just a quick tap is all it needs. The factory did this as an anti-stringing fix.
 
You do know there is a software algorythm that looks at how long the coin switch is closed?

There was a Midway service bulletin issued years ago about the game locking up and it was because the coin switch was being held too long or moved too slowly. Just a quick tap is all it needs. The factory did this as an anti-stringing fix.

There's a dedicated 555 on each of the coin circuits. In our case, we were having random issues with both coin circuits. I figured it was unlikely for the 555 on both circuits to be bad, so I focused on IC's that were common to both circuits.
 
Having identical issue. So I should really take a close look at 74LS02 at 7A or the 74LS74 at 13F if that's yielded good results. I seated the Eproms and the darn thing died. Probably need to pull the boards and reseat the socketed properly.
 
I narrowed it down to a couple of chips on the pcb, but never ended up fixing it. We had a spare pcb, so I just swapped it and shelved the pcb with the coin up issue to tackle at a later date.

The copy of the schematics I have is crappy and hard to read, but I'd look at the 74LS02 at 7A or the 74LS74 at 13F. These are all on the sound I/O pcb.

**edit found a better copy of the schematic and confirmed the locations as 7A & 13F

13F is a SN7474N But 13D is a 74LS74. Are you saying that 13F should be replaced by a SN7474N?
 
13F is a SN7474N But 13D is a 74LS74. Are you saying that 13F should be replaced by a SN7474N?


I'm no expert on this, but in my experience, the 7474 and 74ls74 should be interchangeable in this case. I typically have the 74ls family of chips on hand, so that's what I use.
 
I ordered some 7474's from TwistyWrist as I'm not 100% certain on it either. I suppose I should have looked at 13F before I placed the previous order. I think the 555 Timers are at 13J and 13H.
 
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Replaced both IC's at A7 and F13, however this did not resolve the issue. Going to take a look at these 555 timers. This problem seems to only surface after a few minutes of being on. Seems like after it warms up. I've taken a look at the small connector and it seems to have good contact however I have taken a safety pin and attempted tightening up the connector pins as well as taken an eraser to the edge connector. Nothing seems to help so far.
 
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So, anyone else having this same problem. The solution in my case has been found.
After sending the pcb stack out for repair to Riptor he sends me a message back saying he can't replicate the issue and that it's been running for an hour and so far nothing. Then with a following message he said it finally happened. He was able to quickly find the culprit. Apparently (and I would have never suspected or found this) the C16 tantalum cap was delivering very low readings. It was not blown. It just wasn't passing the correct voltage it should. With C16 replaced the game now happily accepts just as many quarters you want to throw into it. I tested this myself over a period of 15 or so minutes. The real test however will be with the next party when it gets played alot and it is powered for upwards of 8-10 hours. Thanks Riptor for finding the problem. I'd never have found this myself.
 
So, anyone else having this same problem. The solution in my case has been found.
After sending the pcb stack out for repair to Riptor he sends me a message back saying he can't replicate the issue and that it's been running for an hour and so far nothing. Then with a following message he said it finally happened. He was able to quickly find the culprit. Apparently (and I would have never suspected or found this) the C16 tantalum cap was delivering very low readings. It was not blown. It just wasn't passing the correct voltage it should. With C16 replaced the game now happily accepts just as many quarters you want to throw into it. I tested this myself over a period of 15 or so minutes. The real test however will be with the next party when it gets played alot and it is powered for upwards of 8-10 hours. Thanks Riptor for finding the problem. I'd never have found this myself.

Congrats. You can't have BT down during a party :D
 
Nothing says than you like cash or a Rep point.

So, anyone else having this same problem. The solution in my case has been found.
After sending the pcb stack out for repair to Riptor he sends me a message back saying he can't replicate the issue and that it's been running for an hour and so far nothing. Then with a following message he said it finally happened. He was able to quickly find the culprit. Apparently (and I would have never suspected or found this) the C16 tantalum cap was delivering very low readings. It was not blown. It just wasn't passing the correct voltage it should. With C16 replaced the game now happily accepts just as many quarters you want to throw into it. I tested this myself over a period of 15 or so minutes. The real test however will be with the next party when it gets played alot and it is powered for upwards of 8-10 hours. Thanks Riptor for finding the problem. I'd never have found this myself.
 
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