Need Help Diagnosing Powder Coat Oven Issue

[thofdahl]

Looking for help diagnosing my powder coat oven issues. I bought the oven a few months back, pre-owned, and was able to test it before purchase and all worked well. Got it home where it sat for 3-4 months while I waited for 240v electrical install in my shop. Moved the oven there 2 weeks ago after the proper electrical was installed.. plugged it in and it turned on and heated up into the 200 degree range before I shut it off and unplugged it for the night. Went back the next morning, turned it on, elements turned on and began to heat up and then suddenly cut off in the 180 degree range and since then I have not been able to get them to even turn on again. I replaced the Auber Instruments PID controller with a brand new one thinking that could possibly be the issue.. no change. Also tried a new toggle switch for the heating elements and that had no effect either. The PID controller lights up and the light inside the oven turns on and off. Any body have any suggestion what to check next? I did not build or wire the oven and have never done so before so I am a complete rookie when it comes to this. Any suggestions are greatly appreciated!

Here are some photos, sorry they aren't extremely detailed but it's what I have on hand right now.

 

[CJ7VFR]

Did you check the breaker for the 240v circuit that the oven is plugged into? Maybe it tripped when you turned the oven on the second day.

Jim

 

[LXCam]

Have you verified you still have 240volts at the unit? I'm not sure if the controls are strictly 240 or if this required a three wire service with a neutral and the controls are 120. But these always a chance the sparky has a bad connection somewhere. I'd start with that before you dig any deeper.

 

[thofdahl]

I did check the circuit. I also plugged it into another circuit that runs my 240v air compressor and same issues. Again, I am a complete novice, especially when it comes to 240v wiring.. what do you mean by sparky?

Based on the wiring in the box I would say it requires a 3 wire service. It is labeled; line 1, neutral, line 2.

 

[LXCam]

Well I hoped on a puter so I could see the pictures. Yes it's a 3 wire service and does have a neutral. Sparky meaning electrician.

Do either of the relays activate when you turn it on?. If not double check you have 240 volts between L1 and L2 as well as 120 volts line to ground. I don't know how you checked it against the other circuits you listed cause neither of those would have the neutral required to operate the controls for this unit.

Do you have a multimeter?

 

[Movover]

that 2nd switch is missing a wire? and where is that open wire labeled 8 go ? you need to get a diagram drawn up

 

[LXCam]

A diagram would be very helpful but I can figure out what's what if you post a picture of the face plate so I know what switch does what. If you can get your hands on a multimeter so we can run some tests I'll gladly PM you my number and we could do this over the phone.

 

[tyme2par4]

It's possible the elements are fried, but I'm asuming there is more than 1. All of them dying at the same time seems rather unlikely.
Are the elements controlled by a thermostat? That could be fried.

Also do yourself a favor and properly ground it. That fourth pictures scares me a bit...

 

[CJ7VFR]

that 2nd switch is missing a wire? and where is that open wire labeled 8 go ? you need to get a diagram drawn up

It also looks like one of the switches, that one with the yellow wire connector, is not fully seated onto the male spade connector of the switch.

Jim

 

[thofdahl]

Well I hoped on a puter so I could see the pictures. Yes it's a 3 wire service and does have a neutral. Sparky meaning electrician.

Do either of the relays activate when you turn it on?. If not double check you have 240 volts between L1 and L2 as well as 120 volts line to ground. I don't know how you checked it against the other circuits you listed cause neither of those would have the neutral required to operate the controls for this unit.

Do you have a multimeter?

I do have a multimeter. I checked it by plugging it in to another 240v outlet that is on a separate circuit. I need to do some research into how to test the relays. It used to make kind of a clicking noise and then a real low hum noise.. now it makes no noise whatsoever.

 

[thofdahl]

that 2nd switch is missing a wire? and where is that open wire labeled 8 go ? you need to get a diagram drawn up

The second switch is for a fan.. which is not installed or wired. #8 is a 4th heating element. There are 4 elements in the oven and only 3 are connected as of right now. Again this is not my build and I have no experience. I bought it used and very inexpensive. So any insight or advice is appreciated.

 

[thofdahl]

A diagram would be very helpful but I can figure out what's what if you post a picture of the face plate so I know what switch does what. If you can get your hands on a multimeter so we can run some tests I'll gladly PM you my number and we could do this over the phone.

Switches in order from top to bottom: Power, Heaters, Fan, Light

 

[LXCam]

Fist things first. You need to test both L1 and L2 to the neutral and make certain you have 120 volts and then between L1 and L2 and confirm you have ~240. If you where able to plug this into the welder or compressor circuit there's a problem. Neither of those have the required neutral that is needed to operate the controls.

BTW, retired sparky here that specialized in controls.

Also I need the schematic to the heater controller.

 

[LXCam]

Also do the relays have 120 v coils or 240 v coils, it looks like they are 240 but I really can't tell.

 

[CJ7VFR]

Since you have the multimeter, maybe start by checking to see if the things that need power are getting it as LX said.

Start by seeing if there is power coming into the cabinet via the cord/plug that is connected to the wall. See where it is connected, and see if it has power before any switches are turned on.

If it is, turn on the switches for the power and see if the power is coming out of the switches. Maybe one of them is bad. If not, check to see if the items that get power from the switches are powering on or not.

You can also do some continuity checks with your multi meter. See if the wires all have continuity from start to finish. Also check the continuity of the switches and relays. Maybe a relay has shorted out, and pins of the relay are shorting to each other when they shouldn't be until they have power.

Try the simple stuff first. I like to call it the "dumb guy stuff". Once you start doing that, you might find the problem is something simple.

Jim

 

[nsula_country]

Pic of inside of control box clearly shows 2 lines, 1 neutral, and the ground is not hooked up... Possible ground was touching case back feeding and "acting" as a neutral to enable controls.

You say the PID controller powers on and the lights work. That shows the neutral appears to be correct.

I'd poke around to see what powers the coils to the relays. Make sure the relays are pulling in. It appears that they are line voltage coils, no xformer.

Make sure that L1-N is 120v, L2-N 120v, L1-L2 is 240v where cord comes into box.

All else fails, unwire elements and ohm them out to prove they are not open.

CT

 

[thofdahl]

Just for future reference.. the wiring in my shop has a 208v leg and the way the oven and the outlet were wired allowed 208v to the contactors and fried them. 2 new contactors and $40 later and the oven has worked flawlessly.