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Snackshop 4000 Electrical Gremlins


hillridge

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I have an old Snackshop 4000 that I'd like to use in our community shop to dispense consumables, but it has a couple odd electrical problems that need to be sorted out first.  

1. It will randomly accumulate credit without anyone putting money into it

2. It will also randomly eject coins as if it is making change  

I haven't been able to verify if #1 has to happen before #2 starts happening, as both are seemingly random and infrequent enough to not be easily observed.  The machine works fine in all other regards, so I'd really like to get to the bottom of this.  I've very experienced in electronics troubleshooting, but was hoping someone with more vending machine experience could point me to a good starting point.

Thanks!

 

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On 2/2/2017 at 1:53 PM, AngryChris said:

Easiest fix is to send the board AND coin mech in for repair.  It shouldn't cost more than $150.

I think I paid less than that for the entire machine, so I'd like to fix it myself if possible.  

 

On 2/3/2017 at 10:06 AM, AZVendor said:

Make sure you have a new, working florescent bulb in it.  If the bulb is dark at the ends or flickers you'll get issues like you have.

I disconnected the light just to rule this out, and it's still happening.

All signs point to some sort of EMI issue.  I've noticed it happen while someone is TIG welding across the shop, but I also think less noisy activities have also triggered it.

Today I installed a line filter to see if it improves things, but the only way to test is leave it plugged in and see what happens. Unless there's a particular circuit to look at on the main board or changer, my next step will be ferrites on the cables and/or better shielding around the main board/changer.  

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There is a line-in filter that plugs into the bottom of the logic board that you may not have on it right now.  If your power in to the board on the lower right side is just wires into a connector that's plugged into the board then you don't have that filter.  Email me at rbepic4gatgmaildotcom if you need one for the machine.

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Line filter seems to be working so far, so now I'm chasing other things while waiting to see if it fails.

The machine has a Lutech 8000 bill validator on it, does anyone have a link to a manual for this?

It accepts bills fine, but no credit appears on the machine.  I checked all the plugs, and they seem to be secure.  Next step?

 

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If the board on the lutech kit OR the validator is defective, you can experience the unregistered credit. Those lutech kits are known to go bad and the "fix" is to replace the kit.  I'd bet it's bad.  It may cause other problems too.

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3 hours ago, AngryChris said:

If the board on the lutech kit OR the validator is defective, you can experience the unregistered credit. Those lutech kits are known to go bad and the "fix" is to replace the kit.  I'd bet it's bad.  It may cause other problems too.

I eventually want to hack some custom hardware onto this machine, so I'm trying to get a better understanding of how it all works.  The Lutech is interfaced to a Mars MC5000 changer.  Are there any resources out there that explain the pinout/function of this interface or the communication protocol?  The Lutech board itself is pretty simple - a PIC, hex inverter, quad AND, opto switch, and a handful of discrete parts.  If I know where to look, I can probably test/fix it.   

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Do what you want but the Lutech kit is obsolete.  You can get a much more reliable piggyback kit that will run a Mars validator.  You should also upgrade the coin mech because the MC series is from the early 80's with no parts available for them.   They also have a propensity to blow their internal board when the coin acceptor is removed or replaced.

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4 hours ago, hillridge said:

I eventually want to hack some custom hardware onto this machine, so I'm trying to get a better understanding of how it all works.  The Lutech is interfaced to a Mars MC5000 changer.  Are there any resources out there that explain the pinout/function of this interface or the communication protocol?  The Lutech board itself is pretty simple - a PIC, hex inverter, quad AND, opto switch, and a handful of discrete parts.  If I know where to look, I can probably test/fix it.   

The vast majority of us here don't get that technical when it comes to repairs.  Most of us just replace whole parts when feasible rather than doing any soldering or looking at wiring diagrams.

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  • 2 weeks later...
On 2/7/2017 at 2:49 PM, AngryChris said:

If the board on the lutech kit OR the validator is defective, you can experience the unregistered credit. Those lutech kits are known to go bad and the "fix" is to replace the kit.  I'd bet it's bad.  It may cause other problems too.

I got it working again last night!  The problem was a combination of a broken lutech kit and a loose cable.  The Lutech board had a couple common logic chips that were bad - 74LS04 and 74LS08.  Likely got fried when the power wasn't filtered.

 

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The electronics are really old in those machines. It doesn't sound like you want to put a lot of money in it but...You can buy an Inone technologies kit for it and use modern bill acceptor and changer. 

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