Snackshop 500 relay buzzing

[jimbodean]

Hi everyone, new to the forums and hoping someone can help me figure out how to fix a machine I just got.  It's a Snackshop 500 that I got really cheap, which appears to be complete and is quite clean, but not functional.  I do completely understand that this is old and it's impossible to find parts, etc.  This is just for home use.

I was told from the seller that the service light would come on, and had been coming on for a while, and that by opening and jostling the sliding panel that holds the coin mech, it could be made to work again (there may have been something specific that was jiggled but I don't remember the details now), but that eventually even that stopped working.  When I got it home, I took it all apart just to clean it, put everything back together, made sure all cables were seated properly, etc.  When I turned it on for the first time, the two middle spirals in the second tray rotated once each in sequence.  It makes a buzzing sound that is coming from the relay box, and the picture shows the piece (don't know what it's called) vibrating rapidly, causing the buzz.  No lights go on, no coins accepted.

Before I get excoriated for knowing exactly zero about vending machines, let me state that I know zero about vending machines.   I fully expect this is something trivially easy to debug and solve for everyone on here.  I did read the troubleshooting section of the manual for it, but it didn't help.  Presumably I'll need new parts, which may not be easy in itself.

Any thoughts or advice appreciated!

 

[allen watson]

Rotate by hand all of your spirals for starters. Start with the left top column. You just need to start the rotation then the motor will take over and continue the rotation. 
This may not fix it but it’s the start

[jimbodean]

Thanks! ok just tried that.  I guess the good news is that I know all the motors seem to work now!  Each one completed a full rotation, and the buzzing noise stopped while they were rotating, but as soon as they stop rotating it starts up again (and still not accepting coins).

[allen watson]

Unfortunately I scrapped all my AP500’s (30) and didn’t save any parts. I would look for another machine that someone is throwing away and grab it for parts. These machines are only worth scrap price at best (about $12)

[jimbodean]

Do you have any idea what the issue might be, is it something that can be fixed?  or do these relays just go bad and they aren't repairable?  Just wondering, if you had 30 of them, whether you ever ran across that issue and how you solved it.  Certainly a part swap would be easiest, just not sure what to do if I can't source one (other than scrapping the machine) or find a substitute.  I don't even really know what function the relay serves.  Maybe I need to read the schematic and try to figure out what it's doing and if there's a way around it.

[allen watson]

They rarely go bad. You can try filing the contacts but be sure to unplug the machine. 
 

[AZVendor]

The relay is the credit hold relay.  It buzzes because it's worn out from so many years of use.  At rest the relay is energized while it waits for a credit to be issued.  This really is a scrap machine and you will probably have nothing but problems with it forever and forever.  Motors, motor switches, the credit relay, old coin mechs that you can't find, how to price it, and on and on.  

[jimbodean]

Thanks.  totally understood.  Here's the thing, I got it for next to nothing (a little more than scrap value, but still super cheap).  It's small, it's vintage, it's cool looking, it's super clean, and it's already in my basement.  To get something else that ISN'T going to be problematic, is probably going to be newer, a lot of money, and then back to the hassle of getting the thing in my basement.  I have many other vintage items -- pinball machines, arcade cabinets, etc from the 70s that also are decades past being able to get OEM parts for (though admittedly there are aftermarket replica parts for more common units).  I guess my hope was that, given the relative simplicity of the machine, and the clean/complete condition, that I could reasonably learn how to get it going and then do service on it myself going forward.   But maybe I'm still way off base and it's just not going to be possible with a vintage vending machine?

Thanks to both of you I've already learned two things, that that's the credit hold relay, and that I can try filing the contacts to see if that helps.  I'm much farther along than I was only a few hours ago.  

[jimbodean]

ok so last night I filed the contacts on the relay.  it did stop buzzing for a while, but then eventually started up again.  tonight I'll try actually taking it out and filing them much more thoroughly.  the coin box still didn't accept coins, so I took that out to try and take it apart to clean / debug.  while I had it apart, I connected it to the machine so that I could push the metal coin levers to simulate coins being deposited.  The coils did not turn, but interestingly, the change was deposited properly for whatever selection I made.  For example, I have slot A set to 25 cents, and if I "added" 7 nickels, it would return two.  So it's clearly communicating with the pricing board properly -- just not sending whatever signal is required to the spiral motors themselves.

Is that useful debugging info, or does it suggest a narrower range of potential problems / things to try next?

As per the original test above, all motors are working and complete their cycles when starting a rotation.

[AZVendor]

You might have an open vend circuit.  The power in this machine runs from the bottom right motor backwards through the machine to the top left motor.  Start each motor beginning in the lower right corner and move to the left, then up to the next shelf and to the left again.  When you encounter a motor that won't run to it's home position (not run at all) then replace that motor switch and the one before it.  Either one could be the cause of the open circuit.

[jimbodean]

Thank you!  Ok, just went through and ran all the motors, in the sequence you described.  All of them worked and returned to their home position (one was a little loud, but it seemed to work properly).  One thing I thought of though -- I took all the drawers out, and took out the front plastic pieces (with the letters) to clean them thoroughly.  When I put them all back together, it's possible that I didn't put them on their original drawers.  So I could have the drawers inserted in different positions than they were originally in.  Could that make a difference?  If so, I could try rearranging them.  If not, what would be the next thing to test?

[AZVendor]

There should be a 5 wide shelf in the top 3 locations, then two 10 ct shelves below that with another 5 ct shelf at the bottom.  Check all of the rollers to make sure none are broken or loose/missing.  A mis-aligned shelf will force the shelf pins into the socket behind the shelf and force the female pins out.  You could also have a bad coin mech.  Post a pic of the machine from the outside then of the pricing board and the coin mech so we can see what you actually have.

[jimbodean]

This one is arranged a little differently, it's smaller.  I believe it's Snackshop model 520.  It has 4 rows, which are 4/4/8/4.  I disassembled, cleaned and reassembled each row, which each spiral, roller, etc removed, checked and cleaned individually.  All in great shape.  Great thought about the female pins being pushed out -- I'll go through and check all the sockets to see that they look ok.  The coin mech is pictured, though note that I have taken it partly apart to simulate coins going through to test the rest of the machine (it won't take coins, they go right through -- I think it may need more thorough cleaning).  When I simulate coins, it seems to "return" the correct change, so I believe it's working at least to the extent that it's communicating properly with the pricing board.

[AZVendor]

Okay, that is a multiprice Coinco coin mech.  Good luck finding a replacement for it.  These machines came as 4 price, 10 price and multiprice and multiprice were fewer to be found, especially in this configuration.  Even the pricing board is mounted oddly as they typically were mounted on the sliding panel above the relay box.  The wiring diagram won't help you with said relay box.  I can tell you the black item in it is the time delay module that allows the machine to hold a credit until a vend is made.

[jimbodean]

ok.  first of all, thanks for all the help.  I've gone through many posts, and can see many people over the years asking about old machines.  I now understand the frustration you're trying to save us all from (and also, to try and keep people from selling old stuff to unwitting idiots like myself who don't know better).  😂  But regardless, here I am with this machine, that SEEMS to be really really close to working.  of course I could be wrong.

so anyway, I checked all the sockets to make sure the none of the pins were pushed back, and that checks out.

I was looking more carefully at how things are chained.  At one end is the coin mech.  Setting aside whether I can ever get it to accept coins properly, at the very least, it works when I manually move the levers.  From there it connects to the relay box, with some of the wires going directly through to the pricing board, and a few to the relay itself.  From the pricing board, it goes to both the selector panel, and the big wiring harness to the motors.  There is at least enough successful communication that, with slot A set to 25 cents, when I click the 5 cent lever 6 times, it returns one nickel back to me.  So, coin mech to relay to pricing board, and back to coin mech all seem to be talking to each other.  I am thinking then that the problem is perhaps between the pricing board and the motors?  Or am I overlooking a key part of how the relay fits in.  I add coins, it retains the state of the coins until I make a selection, then upon selection, it activates the correct change -- but why not the motor.

Note also that I tried moving/holding the relay both open and closed, and it didn't ever trigger the motor (but it does make the square parts in the upper right part of coin mech click, though it doesn't seem to do anything else).  (when I manually start a spiral turning, and the motor takes over, the relay stops buzzing and holds strongly to the outside)

I also noticed the coin mech has four wires at the bottom that don't connect to anything.  Are these supposed to go somewhere?

Speaking of wires, would it be work getting out the multimeter and just starting to check the connectivity of each and every wire in the harness, old school style, to see if there's one that's shorted or otherwise without continuity?

Thanks again for all the help.

[AZVendor]

I missed the loose wires before.  They go to the nickle and or dime tube payout switches.  I assume you have those?  If not then your coin mech is junk.  To properly test the machine set price A to .25 which is the .05 and .20 switches to the right and the others to the left.  That will price only motor A.  Now hit your quarter switch 5 times.  Then press selection A and see if motor A will vend.  That is how you test this machine.  The more time you put into it the more I would have been likely to tell my customer that it isn't worth putting more time and money into it.

[jimbodean]

probably not worth the time.  again, your point is well taken.  now it's just a challenge.  I'm not doing this for a living, just a machine that I got that I'd love to get working with some spare time.

I do have the nickel and dime payout switches, and I put those in.  there is nothing I see to connect those wires to even still.

However.  I set price A to .25c.  I hit the nickel switch 6 times -- that should be 30c, with one nickel to be returned.  When I press selection A, sure enough, it returns one nickel.  The takeaway from this is that the coin mech is working, and the price board is working, and the selection panel is working.  I deposit 30c, press selection A, it properly reads the price, and properly returns me a nickel.  But it still doesn't turn the motor on spiral A.  How could all the rest of that work, but the motor not turn?  When motor A is rotated a little bit, it properly works and returns to the home position.  So motor A itself works.  But whatever is sending the signal to the coin mech, "ok, selection a was made, it's 25c, and you need to return 5c", probably is the same thing that should be telling motor A "you should run now".  what is that thing?  voltage on what wire, from where?

 

[jimbodean]

I think I found the problem!  It is the relay after all.  If I hold the metal bar closed tight to the relay (in the direction of the arrow) while I press the selection button, everything works!  So it's either the relay itself, or perhaps the thing that I'm holding back in this picture, presumably a capacitor, that could be bad?  which of these is mostly likely to go out?  I'm guessing I should be able to find a suitable replacement for either of these, if I know the specs?

 

[AZVendor]

If you can find them replace them both.  It's a crap shoot.

[jimbodean]

do you happen to know the specs of them?  neither seems to have markings indicating what they are (and I think you mentioned that I shouldn't trust the schematics).  actually, the schematic says the can thing is a time delay pack, not a capacitor.  not sure where or how to find one.   I wonder -- would something like this work to replace both?

https://www.amazon.com/DROK-Controller-Delay-off-0-01s-9999mins-Adjustable/dp/B07RGT5G1X/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1

edit.. now I'm wondering if it's actually those parts that are bad, or something else.  certainly they aren't working.  but the relay isn't even trying to close.  could a relay fail so thoroughly?  or is it perhaps not actually getting the signal?

Edited September 1 by jimbodean

[jimbodean]

now I'm not convinced it's the relay.  or, not just the relay.  the relay control circuit is getting a steady 19v, which I assume should be 0v unless it has credits and a selection button is pushed?  so that would mean there's a short circuit somewhere..................   but where......   the plot thickens...

[jimbodean]

Just to add some closure to this thread for anyone in the future that might have this issue.  It turned out both the cap and the relay were bad.  Swapped both out for in-spec replacements from Amazon, and it all seems to work good now.  Thanks to both allen and azvendor for the help!