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National 431 Issue


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I have a national 431 that is giving me a "can't home" error.  When turned on, the drum will just rotate back and forth over and over and over.

 

I know that there is a magnet on section 1 of the drum that is suppose to be sensed.  Is there good method of checking to see if the magnet is present (basically where would I find it) and a good method of checking the sensor (also, I am assuming the sensor is located in the front left of the machine).

 

Thanks

Travis

 

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If it is jerking back and forth and not making a full rotation then Walta hit the nail on the head. If it is making full rotations then it may be the magnet. The magnet is on the bottom of the turret and looks like a black circle down by the outside gear. You can test the switch with a meter as it is just a magnetic switch that will read open or closed.

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First thing to do on a national 430 or a431 is replace the lights. Those fluorescent bulbs will mess up the electronics. Then do what walta says clean the wheel and take a can of air to blow out the sensor the wheel rotates through..  

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  I found this National 431Troubleshooting and repair guide in a pdf format on the D&S website a while back. It has a lot good solid information. Its one of the better vending manual I have seen, reminds me of Air Force maintenance manuals a little bit. I would recommend that you read the whole manual or least familiarize yourself with its contents. I agree with Walta and Technivend on checking your wheel first, its the easiest check to make and you can also give the turret motor a quick lookover, make sure its tight and that your driveshaft coupling is not cracked, elongated or missing a pin. Another big culprit to check is your stop pin solenoid assembly.

  A little background on myself since this is my first post. I have been a vending maintenance tech for almost 13 years. I use to work for a small to medium size company for 10 years until it got swallowed up by one of the big boys.

 

Joe

 

http://www.dsvendinginc.com/pdf-manuals/431troubleshootingguide.pdf

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No go on the cleaning of the wheel.  So, the machine just turns back and forth, moving the drum maybe a couple of inches.  If I let it go, it eventually gives me a "motor jam" error.  So is the machine not seeing the drum moving....even though it is, and ultimately thinking that the motor must be jammed?  If so, then next logical item to replace would be the motion sensor?

 

Travis

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  I found this National 431Troubleshooting and repair guide in a pdf format on the D&S website a while back. It has a lot good solid information. Its one of the better vending manual I have seen, reminds me of Air Force maintenance manuals a little bit. I would recommend that you read the whole manual or least familiarize yourself with its contents. I agree with Walta and Technivend on checking your wheel first, its the easiest check to make and you can also give the turret motor a quick lookover, make sure its tight and that your driveshaft coupling is not cracked, elongated or missing a pin. Another big culprit to check is your stop pin solenoid assembly.

  A little background on myself since this is my first post. I have been a vending maintenance tech for almost 13 years. I use to work for a small to medium size company for 10 years until it got swallowed up by one of the big boys.

 

Joe

 

http://www.dsvendinginc.com/pdf-manuals/431troubleshootingguide.pdf

 

Dude. You both have an amazing ( and appropriate ) forum name, and that's an astounding resource you've linked there. 

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OK...so still having issues.  This is what I have done. 

 

1.  Cleaned the Wheel - No Change

2.  Cleaned motion sensor - No Change

3.  Replaced motion Sensor and cable - No Change

4.  Replaced Circuit Card that motion sensor plugged into - No Change

5.  Adjusted wheel to make sure it was spinning in the center of the motion detector - No Change

 

Again, the drum will turn back and forth just a couple of inches.....until the machine gives a motor jammed and can't home error

 

Suggestions on what to try next?

 

Travis

 

 

Travis

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 Have you powered down the machine and hand turned the the turret to see if you have something is jammed? I once seen a can of OJ fall out in the back and jam the turret. Did you check the turret drive shaft coupling to see if its cracked or has broken pins? When they go bad you will usually see white plastic bits and pieces on the wheel.  Have you checked the connections at the interface board and the main board? A loose plug or crimped wire will give you fits also. Both boards can also cause the problem, but the interface board is more likely.  Good luck.

 

 

Joe

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I have not replaced the lamps yet.....I guess I can remove the bulbs and see if that make a difference.  If I try to open one of the vending doors, the machine will stop.  I can then hold either of the directional buttons down, and it will spin in the direction until I let the button go....so yes, it would spin completely around.  I have not adjusted the stop solenoid yet, however it is clicking like a mad man and the pin is engaging the drum because if I want to manually rotate the drum from a stop position, I have to pull the pin down. 

 

I have to go down there tomorrow morning, I will video it and post it.

 

Thanks

Travis

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I think this is probably a bad stop pin assembly that is not disengaging itself from the turret all the time.  If the solenoid or the solenoid switch are weak this could happen.  Not enough voltage or consistent voltage or a worn out solenoid or switch could cause this.

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That chattering solenoid does make it sound like a bad or out of adjusted stop pin assembly. You might want to check the bolt and nut on the pivoting arm of the stop pin. I have seen those loosen up and cause odd problems. Easy to miss that one sometimes.

 

Joe

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Yep....it needed to have the stop pin adjusted.  I guess I need to better understand the operation of this.  This is what I mean.  I assumed that as long as the stop pin was engaging/disengaging the drum, then it must be at least within specification and working correctly.

 

However I went back down tonight and did the adjustment, and its working now. 

 

I will keep an eye on it.  I will tell you, I hate Fresh and Frozen machines.  They are just a pain in the butt when things go wrong with them.

 

Travis

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