2013 North TJ-067 gas roaster Ignition Issue

#1: Post by **smite** » March 4th, 2019, 5:04 pm

Spun off of another TJ 067 thread.

I am hoping someone that could help me with my issue. I am not sure how all of components work together but something that is sending the signal to the ignition switch isn't recognizing that the flame has started. Previously the ignition would only buzz and stay on until the gas started.

For some reason my ignition stays on making the buzzer sound even after the burner is lit. This has resulted in a fuse blowing out which i managed to replace as mentioned earlier. While replacing the fuse allowed me to get the roaster back up and running again something else is wrong and I don't like the idea of the ignition constantly staying on during roasting.

Details on the roaster including pictures can be found here:

2013 North TJ-067 gas roaster electrical troubleshooting

Any tips or pointers would be greatly appreciated.

John

#2: Post by **drgary** » March 4th, 2019, 5:08 pm

John,

Have you traced the circuitry between the ignition and other related components? How does a roaster like ours register that the flame has been lit? How is that relayed to what powers the ignition so it shuts off? Have you checked connections to the ignition switch, and if they're okay, have you tried replacing that switch?

I hope you don't have to do a knuckle-scraping removal of your circuit board to discover this.

Added: I've linked this new thread to my old one, so people can find this one and help out.

#3: Post by **OldNuc** » March 4th, 2019, 5:19 pm

That is a high voltage spark that is generated by whatever is connected to the other end of the electrode. If by some fluke of luck you will find low voltage wiring also attached to that device. That is what you have to follow out and this igniter may actually be a part of the gas control valve. There are a couple of ways that a flame is detected to terminate ignition and there is also a fail to ignite time out to close off the gas. Seems like whatever is detecting ignition and shuts down ignition is not working. This can be controlled by a separate control board or a a part of the gas valve. Which one it is is usually determined by tracing that heavy lead from the igniter back to its source. I suspect there are multiple designs of this roaster so what someone else finds may not be applicable to your version.

Clear, well lit, in focus pictures with enough detail to show related components might lead to some creative guessing. If that is a foreign made combination gas valve igniter then it may not be easily repaired. New gas valves are blindingly expensive even when you can buy them wholesale.

March 4th, 2019, 8:18 pm

Thank you both for the replies. The pictures in Gary's thread appear nearly identical to what my roaster looks like. Is there a specific area to focus on for any additional pictures?

Here are some pictures from my previous thread:

North TJ067 igniter stuck on

More pictures as well:

North TJ067 igniter stuck on

I will see if I can trace the wires from the inside the by the ignition and to the inside wiring in the main control area and take some pictures.

#5: Post by **OldNuc** » March 4th, 2019, 8:52 pm

The actual igniter is the ceramic block with the 3 probes. Need to see the wires attached on the other side and if possible what they are connected to. Most likely the problem will be with what the wires are connected to.

#6: Post by **ira** » March 5th, 2019, 2:17 am

The spark should stop when it senses heat or a resistance change from the ionization of the air. If there is a thermocouple or thermopile that is used for sensing it probably needs to be replaced. They should be available at any plumbing or HVAC store for a few dollars.

Ira

#7: Post by **drgary** » March 5th, 2019, 2:26 am

Wouldn't it be great if it's as inexpensive a fix as that!

#8: Post by **OldNuc** » March 5th, 2019, 10:27 am

Other than being some type of Chinese gas valve it could be simple but thermocouples do not fail to ON so that simple fix is probably a non starter and you are right back to the ionization detection circuitry which may not even be physically assessable. All that we know is that the power is applied to the HV generator continuously. Further the timing circuitry is not cutting off the gas on a failure to detect flame or it is an independent circuit. AIs this a flame detection failure or is it a failure of the solid state power to spark generator to cut it off?

Need good pix or the correct schematic and not a basic block diagram.

#9: Post by **drgary** » March 5th, 2019, 10:38 am

John,

Does Mill City suggest replacement parts? If so, what have they suggested swapping out?

#10: Post by **ira** » March 6th, 2019, 2:29 am

Neither thermocouples nor thermopiles fail to on, so the spark keeps going because it never sees heat.

Ira