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Hi all,
    My USS-8-64 has stopped vending.  Over the winter there was a power outage and when the power came on the USS-8-64 would no longer release a soda.  It powers on and cools but the quarters drop right through the coin mech to the coin return.  The coin mech is a Mars TRC-6200.  I bought a replacement off Ebay but it didn't work either.  Is there any other possible cause likely or do you think the problem is with the coin mech and I just got another bad one off ebay? Thanks for any input.

John

1. Have you tried turning the bottle cams over to see if it's stuck in a vending cycle?  That would hopefully reset the switch at the bottom to put it back into 'coin accepting' mode

2. An easy way to troubleshoot the coin mechanism vs. the machine is to build a free vend switch, or wire the plug to match.  If it vends then, it's the coin mech, if it doesn't then it's the electronics inside the machine (solenoid or switch)  http://soda-machines.com/discussions/index.php/topic,871.0.html

Thanks.  I'll try the free vend thing.  Do you know if my machine needs the connection to pin 7 too? Could I just use a jumper and do a short connection to 3 to see if the vend happens?  not sure what the "bottle cams" are. 

You don't need the connection to pin 7, just remember you are dealing with 120V so don't mess around with live wires.

The vending cams are just the tumblers that rotate the product out, so just try to vend product, see if that resets it.

Thanks.  The cams seem all locked, won't turn to vend.  I'll try the free vend after a trip to Radio Shack to get a switch, in the morning.  Thanks for the advice.

Okay.  So I made the "free Vend" switch.  When I push the switch, it fires the vending solenoid to unlock the bottle cams and I can get a soda from the machine.  So, I think that means the problem is in the coin mech. It appears the top solenoid in the slug rejector is not withdrawing the steel gate that keeps the quarters from dropping through and redirects them to the coin return.  Any suggestions to track down the problem.  Are there any continuity tests I can do from the Jones plug to the ribbon connector in the Slug rejector to test for broken wires.  Is it possible that something is "fried" on a circuit board? Thoughts?

Do you have enough nickels in the change tube?  There is a switch about halfway up that has to be engaged, that will pull in the CREMs ('steel gate').

If that doesn't work, then it could still be the vending switch, do you have a way to test voltage?  Using the free play switch, check pin 7 of the Jones plug before hitting the button and after, you should see it off before and on after (or vice versa).

I would check the change tubes first. Since the issue is the same with the replacement coin mech, I would look into the switch like tkaz says. The only circuit board is in the coin mech. There may be a stuck relay. Keep fiddling......

Thanks for the ideas.  I just got busy at work and may not get to test the machine for a few days.  I never have had nickels in the tubes as long as I have owned the machine and never had a problem with it for years.  I'll try adding some, and try to test the 7 pin and get back to you.  Thanks!!

Download a manual, follow the programming instructions, & see how it goes, fun fact, if you disconnect the ribbon cable with the power on, the coinmech will forget which coins it was programed to accept. MARS ha s manuals online to download for free on the older mechs.

I looked on the MEI site and didn't see one for the 6200.  I see one general one for the TRC series, but in the manual they only mention the 6000/6010, 6510, 6512, and 6800. 

http://www.brockcompany.com/MEI_Training/resources/TRC-Teach-Procedure.pdf

I didn't seen to be getting voltage between socket 7 and socket 2 with the free vend on or off, though the little "Have a Coke" light on the front lights up when the free vend switch is tapped.  I did discover that I seem to be getting 120 volts between socket 2 and the chassis though.  I don't think that should be that way?

I unplugged the machine and tested and I have continuity between sockets 1 & 2.  Is that right? 

Sounds like a short to the cabinet. With no power applied check every inch of the wiring. First any bits touching the shell. Will get this sorted. Just takes longer sometimes.
Creighton

If only I'd discovered this problem when the weather was lousy out and I didn't have tons of yard work to do...  Hopefully I'll have time this weekend.

So, I'm really getting perplexed.  I've been tracing the wires and I can't seem to find a short between the hot and the case.  Doing some more tests with the meter.  When the unit is plugged in, I get 120V between the case and the #2 socket of the Jones socket. I also get 120V between between#1 and #3.  I get no voltage between #2 and #3, so I assume there is no short with the Neutral, Its with the case.  BUT!!!, with the unit unplugged, I get no continuity between the case and #1.  I do get continuity between the case and the ground prong on the plug, but not with either blade (Hot or Neutral) on the plug.  Any thoughts??  My only guess is there is a short from the secondary side of a transformer?  I'm not any kind of electrical expert so I'm looking for other explanations for this combination of readings?

Trying my best to understand, so bear with me.  First step is to make sure you aren't in a vend cycle, so try to vend product, put a bottle in a row and turn the lever to vend.  That will reset back to 'ready to accept coins' status.  Test continuity between pins 1 & 6, it should be a closed circuit. 

If you want to try a little further, use the free play switch to engage the solenoid, but don't vend.  Check the continuity between 1 & 6 again, it should be an open circuit.

Problem that I'm trying to isolate is the carrier switch at the base of the vending stack, a common problem that the free vend switch won't necessarily troubleshoot.

I assume I should take those readings with the unit plugged in, power on?

Actually it doesn't need to be powered on, just make sure you are not in a vend cycle, the switch works regardless of being powered.

Okay. I tested it with the unit unplugged and I had continuity, a closed circuit between 1 and 6.  I plugged it in and pressed the "free vend" switch and it engaged the solenoid and opened the circuit.  I turned the cam and released a bottle and the circuit closed and I once again had continuity.

Sounds like everything in the machine is fine, when you plug the coin mechanism in with the machine powered on, do you hear the CREMs pull in?  Did you ever run through the calibration from the Mars manual link on the first page?

What are the CREMS? I haven't done the calibration yet. I was more concerned with the apparent short to the case.

Coin Reject ElectroMagnets, they are behind the slug rejector in the coin mechanism, a set of 'fingers' that push out when the machine is in a vend cycle and cause coins to reject, so you can't add extra money.  When you plug in the mech with the machine powered, you'd hear a clicking, which is the CREMs pulling back.

Ok, with the machine powered, I plugged in the Coin unit.  No clicks or buzzes, unless they are very quiet and I can't hear them over the compressor running.

You'll hear them, or better yet, you can see them activate if you remove the rejector from the mech and then plug it in. It's the one or two metal bars with fingers protruding into the rejector.

Oops, I see that was mentioned above. Likewise, if the magnets are energized, these can be humming, and can be pulled out from the electromagnets. If the magnets aren't energized, it may actually be the coin mech. These used to go bad frequently on the route. If you can arrange to borrow a verified working coin mech, try plugging that in and see what happens.

I tried the other coin unit that I got on Ebay.  I heard no clicking either.  This one is missing the front panel.    Does anyone know if the ballasts for the fluorescent bulbs are like transformers, with a primary and secondary?

And you tested that mech with the nickel coin tubes filled up past the switch?  How about the dimes?

Myself would solve one problem at a time. Pictures/photos etc... may very well speed up both issues solution.
Creighton

Hi again all,  Creighton, I do agree with you that focussing on the problems individually might help.  I started this thread with the vend issue so I've been trying to work the suggestions that have come in on that.  In the process, I discovered the "short" issue and due to the safety concerns, thought that I should address that, as a priority, though continuing to follow up on any, much appreciated suggestions that are coming through about the vend issue.  So, I have added the coins as tkaz suggested. 20 Nickles and 20 dimes, though not through the "learning" process.  Still getting no clicks from the CREMs.  I,ve attached some pics of the coin unit.

And here are some of the Shorting...