TNF66 issues

[Lilixc]

I have a TNF66 kiln with a DTC 100C controller. Yes, I know it's old. I had issues with getting it up to temp so I purchased a new set of elements, relay and thermocouple from Paragon. I had to do one firing with the new elements only - the kiln only fired to 1822 before it stalled, and that was after 10 hours. I programmed it to go at 270 degrees per hour to 2194, bottom of cone 6. It couldn't even hit bisque with the new elements. I got the proper relay and the thermocouple, and had to do major surgury - the kiln is sol old that the parts are not exactly the same. The relay had prongs in different places, and the thermocouple looked like a football instead of the cube block that it came with. So I had to drill holes and reassemble the entire thing which was a real pain. 

Today I tried to fire up the kiln but the controller was acting abnormal, it wouldn't get out of Idle mode until many tries. I finally was able to get it to program but then it would only register the temperature in the kiln immediately and not rise. The temp was not changing at all even though the elements were glowing and it was definitely hot. I restarted it and the temp was higher, then I restarted that and the temp was higher than the previous, but there was no rise in temperature. 

 

I also noticed a slight hum on the kiln when I started it, almost as if the relay did not turn off. At one point I was so frustrated, I pressed stop three times in a row and the relay started clicking continuously and I couldn't get it to stop without unplugging it. 

I've ruled out that it can't be the new elements, or the power, but I'm not sure if the issue is now - the relay, thermocouple of this darn old irreplacebile DTC 100C controller. 

 

If anyone is thinking of buying an old kiln from Offer up, DO NOT DO IT. This kiln has cost me 700 and I have not even been able to fire this, it's caused at least three to four week of grief and now that it has all new guts, I'm told I need to get a new controller. AT that point,  I should have gotten a new kiln in the first place. 

 

Can someone please help? 

[Bill Kielb]

Sorry to hear about the difficulty but it does sound like your thermocouple setting / type/ polarity  may not match the controller. Also there may be default settings that could be an issue. Why doesn’t your new thermocouple match, is t the right one, right type? Before all is lost, I would suggest looking at ALL the factory settings and making sure they match your kiln, your thermocouple, it’s polarity, etc….. Relays can change form over time, so ensuring the coil is still the coil, the no and nc contacts are still functioning as intended also important. The relay in this kiln is super standard, are you sure yours matches electrically?  The voltage for this kiln is 240 v 3 wire so L1, L2 and a ground in North America (No Neutral). The kiln needs to be on a 2 pole breaker, 20 amps. Do you have the wiring diagram and are sure the new parts are installed and match the function of the diagram. The new elements have to be installed in series as shown in the diagram. Your kiln is fairly small so easy to trace these faults logically. Still the DTC 100:is fairly old, things don’t last forever.

some documents that might help
Tnf 66 diagram https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/WTNF66.pdf

DTC 100 manual https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/DTC100.pdf

Can you post pictures of old / new thermocouple and relay as well as the kiln equipment tag.

Edited March 1, 2023 by Bill Kielb

[neilestrick]

Sounds like maybe the thermocouple is too close to some metal. Make sure there's plenty of clearance between the thermocouple and the metal jacket of the kiln. Could also be that the controller is dying, which wouldn't be all that surprising given its age.

Humming of the elements is normal. Relays should be quiet.

FYI, the DTC100C can be replaced with a modern controller no problem. The Bartlett RTC100 is a direct replacement, and the Genesis or V6-CF can be made to fit with minor modifications to the kiln panel.