Minnesota Clay Co. USA Technical Info - Kiln Repair

Specific information on how to diagnose and repair common kiln problems. These are the answers to the questions that we are asked most frequently.

How can I correct a value that’s been incorrectly typed before pressing ENTER?
Clear the display by pressing all zeros, then input the correct number and press ENTER. When a cone value has been incorrectly entered the process is slightly different. After pressing 0000, press ENTER. The display will again ask for a preheat value and then a cone value.

How can I change only one value for a RAMP/HOLD firing profile without re-entering the whole program?
Follow tthe instructions for entering a new program and just press ENTER for every value that will remain the same. Make a change in the value that is incorrect, then continue.

How can I change the program after it has already started?
Press the STOP key. This will stop the firing. Use either the CONE FIRE MODE or RAMP/HOLD MODE to input the new firing profile for the remaining portion of the firing. Press START to resume the firing. The controller will automatically determine where to start the program (based on the current internal temperature) and proceed with the adjusted program.

The kiln shuts off too early.
The kiln can be restarted if the cones on the shelf indicate an under-fired load. (This should be used only if you were present when the kiln fired off.) The cones are no longer accurate if they have cooled much from the time of shut off. To restart follow these steps.
Press CONE FIRE or RAMP/HOLD to view the firing just completed.
Press ENTER to accept any of the segments that are correct until the point where the cone number or final firing temperature is requested.
Program in a hotter cone or higher firing temperature. You could also add a few minutes of hold time at the final firing temperature.
Press START after the reprogramming is complete. The kiln will begin firing based on current temperature and will fire to completion using the newly programmed data.
Helpful hint If the firing is just slightly under fired, program five minutes of hold time at the final firing temperature. This will allow the sections of the kiln that are somewhat cooler to catch up to the hotter sections.

The kiln displays CPLt but the kiln won’t cool off.
Check the elements to see if any are still glowing inside the kiln. If a whole section of the kiln is glowing, a relay is stuck. Unplug the kiln and contact your distributor for further information.

At night I see a blue flash coming out of the control box when it clicks. Is it serious?
The flash occurs when the contacts open causing a small arc. This is a normal occurrence and should not be a concern.

Review the program to ensure that all segments of the profile have a value entered. Also, check the alarm to see if a value has been entered that is lower than the room temperature. The default setting for no alarm to sound is 9999.

The kiln is plugged in, but there is nothing on the display.
First check your circuit breaker to ensure it has not tripped. If the circuit breaker is okay, check the fuse. The fuse is located on the bottom of the KM 1 Controller and on the lower left side of the kiln mounted controller. Turn the knob a quarter turn counter-clockwise to remove the fuse. Check the fuse wire, and if broken, replace the fuse. If the fuse is smoky, replace it. After the fuse is replaced, if the new fuse blows, check for other possible causes. A blown fuse may be caused by a short in the circuit or a power surge.

Some segments of the display are dimmer than others.
When a few segments of the LED-display become dimmer than the others, the problem may be the result of age, indicating the circuit board may soon fail. Another possible cause is exposure of the controller to high heat. This situation needs attention. Do not use the kiln when this problem is present. Contact us about this problem.

The thermocouple is flaking.
Flaking is normal with Type K thermocouples, especially when high fired. Use a soft bristle toothbrush to remove the flakes and vacuum them from the kiln so they do not attach to your ware. Remove the thermocouple element periodically and check it for thinning.

The end firing temperature is different now than when I first got my kiln and the results do not seem quite right. What should I do?
After about 50 Cone 6 firings, or 150 Cone 04 firings, it is necessary to replace the thermocouple element. When the temperature seems to drift, it is an indication that the thermocouple is becoming thinner and wearing out. Another possibility is a cone correlation difference. As elements age it takes longer and longer for the kiln to reach temperature. ConeFire Mode programs will automatically lower the ending temperature to compensate for the added heat work induced by the increased time.