Replacing fried electronics

[Skeleton Man]

Hi all,

I have a Cornelius 50-0842 Pepsi machine which I plan to restore. The refrigeration works fine, but nothing else works.

The coin mech has one pin melted to the connector for that wire on the machine, and the relay is shot !

Relay has a large 500MF capacitor soldered to it which has exploded ! (massive hole in the side), and some value resitor between a couple of the pins, which is so badly burnt I can't read the value !!

Last but not least, when I got it all the lights were blown.. (buttons, exact change, even the fluro tube for the sign)

I measured the voltage at the light socket for one of the buttons, and it's reading about 45V AC (should be 110V!)

What could have caused this much damage ? Power surge ?

I would be much appreciative of anyone that can tell me where to start.

Regards,
Chris

[johnieG]

For Petes sake man,don't plug the thing in again, you are asking for it!    (unless you are trying to collect on a life insurance policy sold to you by daffy duck)

as for what caused it, probably the last owner did some creative rewiring (which literally blew up)i f what you say is true, sounds like quite a mess! so which pin on the coinmech is melted?  some pictures may help, & there should be wiring diagram pasted inside the machine somewhere on the inside door, we'll start here & see where it takes us...hopefully not to the scrapyard. '>

out of curiosity, did the capacitor have any markings on it for polarity, (one side says "+") or was it a metal-can type that you find on electric motors...just that it sounds like an electrolytic rated for D.C. that blew-out on A.C. or over voltage..almost like they where trying to rig up some kind of a time delay for the relay circut...hmmmm

so post some pictures & we'll see what old "sparkys" been up to... '>

[Skeleton Man]

Quote (johnieG @ April 15 2005,9:33)

For Petes sake man,don't plug the thing in again, you are asking for it!    (unless you are trying to collect on a life insurance policy sold to you by daffy duck) as for what caused it, probably the last owner did some creative rewiring (which literally blew up)i f what you say is true, sounds like quite a mess! so which pin on the coinmech is melted?  some pictures may help, & there should be wiring diagram pasted inside the machine somewhere on the inside door, we'll start here & see where it takes us...hopefully not to the scrapyard. '> out of curiosity, did the capacitor have any markings on it for polarity, (one side says "+") or was it a metal-can type that you find on electric motors...just that it sounds like an electrolytic rated for D.C. that blew-out on A.C. or over voltage..almost like they where trying to rig up some kind of a time delay for the relay circut...hmmmm so post some pictures & we'll see what old "sparkys" been up to... '>

The wiring diagram is old and covered in mold so it's almost unreadable.. (you can make out small bits of info but that's it)

One thing I can make out is that the machine has a time delay relay.. which I *think* is mounted to the door.. (so much wiring I can't tell if it's just a block for joining wires, or a relay)

Will update with pics later today

[Skeleton Man]

Pictures are available at: http://www.guestwho.com/pepsi/

Pin 1 on the coin mech is melted ("hot" 110V):




Coinmech pinout here (copied from the label):

http://www.guestwho.com/pepsi/coinmech.gif


The capacitor is indeed an electrolytic and polarised..




This is what remains of the wiring diagram:



Nothing in the front has power (no lights, nothing), but the compresser runs perfectly..  that I don't understand

I tried applying AC to the coinmech via a power cord to see if it would show signs of life..  I figured if it was working, the change ejector switch should work.. (little switch on the coin tube that dumps all the coins)..

The above did nothing, so I opened the coin mech and pulled out the logic board... It appears that a diode has burnt out and gone open circuit..  (I am assuming it's for reverse current protection and should conduct one way..)

Here's a picture of the board (Coinco S759800A):

[Skeleton Man]

Update: Removed wiring harness going to the front of the machine (large white plug in front of the compressor). Voltage was O.K (120V) at that connection point.  Reconnected the plug and viola!, the pepsi sign on the front came to life.

Next I rigged up the free vend hack (except hard wired as I don't have a switch). Plugged the machine in, and "click!" goes the relay !

I'm gonna buy some cans later today so I can test the vend mechanism..

[johnieG]

yep, quite a mess! but at least it seems to be semi-functional, the burnt component on the coinemechs' circut board is a Zener diode (voltage regulating diode) without it the board will have no D.C. maybe if your lucky, it didn't take out the other I.C.'s when it blew...your 'pic's are a little fuzzy, but the smaller relay is indeed hooked up for a time delay, the capacitor probably dried up & blew open, the small round bead is a power diode, used to convert the A.C. to D.C. to power the cap. & resister time circut ( for you electronic geeks out there, R x C = T) whats the value & voltage listed on the 'cap? & whats the color coded bands on the resitor (in order left to right) if it's not damaged (the resistor) you might just have to replace the capacitor to get it going again, '>

the little thingy that's spot-welded to your coinmech's pin #1. is the remains of a female connector hopefully not from your jones socket... '>  

It may be a delay circut like the one shown below, just to give you an idea of how it works,

[Skeleton Man]

Why would you need to delay the cut in of the relay ? (ie. what difference does it make ?)

The cap is 50 uF, 250V, the resistor is too burnt to read the stripes. I can measure it with a meter tho if neccessary.

I have heard of zeners, tho never used them (I have a basic knowledge of electronics). I shall try radio shack and see if I can find one.. only thing is I can't read the markings..

The vending mech is simple, it just has metal prongs that the cans rest against. You hit the flavour button and the prong for that column goes down, releasing the can.

I tried out the mechanism by putting a weight on the sold-out paddles:

Solenoid 1: stays down for as long as I hold the flavour button, makes a *lot* of noise (vibrates like ####!!).
Solenoid 2: goes down when I hit the button, stays down until I unplug the machine, not much noise.
Solenoid 3: stays down for as long as I hold the flavour button, not much noise.
Solenoid 4: same as above.

I am guessing solenoids 1 & 2 will need to be replaced ?

What needs to be fixed so the mech works correctly ? (ie. prongs go down, can releases, prongs go up)

I'm aware that the female connector is welded the pin, I had to cut the wire to get the coin mech out. There is no jones socket, simply a collection of seperate wires with female connectors.

Half the connectors are coming off the wire, and I bought new ones, but I can't get them to crimp securely (I'm just using a large pair of pliers).  I would like to put in a jones socket so the coin mech comes in and out easily and looks neat, but with a welded pin, I guess I'm stuck... (unless I replace the jones plug on the coinmech)

BTW, many thanks for the help !!  '>

[johnieG]

Hmm, no jones socket eh? someone has been getting creative with the machines wiring...& I have no idea why your machine is wired the way it is, I'm only suggesting possible wiring diagrams to help you try to trouble-shoot your machine, since I'm not right there next to it, now back to the relay circut...

it could be a delayed cut-out relay circut, (see attached diagram) which would hold the relay closed for a given amount of time after the button is pushed,

the empty spot on the front door used to hold the bottle opener, so this machine must have been able to vend bottles at one time & was converted over to cans I assume,

the Burnt zener diode on the coinmechs' circutboard functions like the other diagram I'm attaching...it's probably a 12 volt 1/2 watt form the size of it, figure out which way the polarity marking (white stripe) is located & install the new one exactly the same way, or it's toast...double check the under-side of the board for burnt/lifted lands (copper wiring tracks) that may have been opened up the "accident"

[johnieG]

And this is the Zeners functional diagram...

[Skeleton Man]

I'll try replacing the cap/resistor and see what happens.. delayed cut-out makes sense to me.. it may be what keeps the vend solenoid down for the correct amount of time.. (ie. just enough time after you press the button, for it to vend a can)

If I can get a new jones plug & socket, I'll rewire the machine.. (gotta pull everything out when I clean/repaint the machine)

Your diagrams are very helpful, gives me a better picture of what I'm dealing with '>

I'll try radio shack for the zener diode.. gotta try and find some globes for the flavour buttons too..  (nobody seems to have them.. at least not the 110V variety.. (only 12V))