What do I do if the control display doesn't show anything?

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  • See the Sales FAQs for Frequently Asked Sales and Preorder Questions
  • The Knowledgebase is organized into a series of questions and answers having to do mostly with technical troubleshooting and understanding of kilns.
  • Although we write this for our own kilns many of these articles apply to other makes - although L&L takes no responsibility for that.
  • Many Knowledgebase articles have Actions, PDFs and Videos associated with them.
  • Actions are specific actions for you to take during the troubleshooting or repair process.
  • Each Action may also have Videos and PDFs associated with it and, in addition, specific Cautions.
What do I do if the control display doesn't show anything?

On/Off Switch

  1. Make sure the On/Off Switch is turned on. Turn it on and off.

Control Fuse

  1. Check control fuse in side of control box. Twist open the fuse holder and physically check the little fuse. You can see if the metal element inside is melted if it is blown. You can also use your digital multimeter to check continuity across the fuse.

Branch Fusing

  1. Check the branch element circuit fuses inside the control box. All kilns with more than 48 amps and many 3 phase kilns have branch fuses.

Plug & Cord (if you have one)

  1. Make sure the power cord is plugged into the receptacle. Reseat plug.
  2. With power off examine the electrical cord. Look for burned or melted areas and breaks or pinched sections. Look closely at the head of the plug. If there is an internal problem with the wires and the plug parts you won’t be able to see it but you may detect a softening or melting of the plastic at the plug head.
  3. With power turned on and panel open check voltage at the Power Terminal Block. If you see no voltage there then you know something is wrong with the power source. CAUTION: This test should only be done by an experienced person familiar with electricity and its dangers.

Circuit Breaker / Power Source

  1. Check voltage at the receptacle. CAUTION: This test should only be done by an experienced person familiar with electricity and its dangers.
  2. If there are approximately 240 volts coming into the control transformer (terminals 4 & 7) and there is no voltage coming from the transformer (across terminals 5 & 8) then you have a bad control transformer and it needs to be replaced.
  3. If there is no voltage coming into terminals 4 & 7, then test for it at the Power Terminal Block where the power cord comes in. If there is power there then look for a bad connection or wire between the power connection block and the transformer, i.e. a bad toggle switch, wire, or 1/2 amp fuse holder. If power is not there then go further back on the line and measure the voltage. Keep going until you find voltage, then look for the problem between that point with the voltage and the last point checked that had no voltage.

Control Board

  1. If the transformer is OK and you know you have voltage going to the control board but the control still shows no display then the control board needs to be replaced.

 

 

Additional Actions to Take

  1. Make sure the circuit breaker or fused disconnect switch is turned on.
  2. If you have a circuit breaker flip it back and forth to make sure that it is really on. Some circuit breakers, if they have tripped, will not be obviously in a tripped position. By flipping it back and forth you will reset the circuit breaker.
  3. Check voltage of your power supply at the receptacle using your multi-meter set to the next highest AC voltage above 240 (typically this will be 600 volts but may be 250)
  4. Check fuses for voltage continuity. You can do this with your multi-meter.
  5. Make sure fuses or circuit breaker are/is the proper amperage and type. See your wiring diagram for the required fuse type.

CAUTION: This test should only be done by an experienced person familiar with electricity.

  1. The control fuse is normally located on the side of the control box.
  2. Twist open the fuse holder and physically check the little fuse.
  3. If the fuse is blown then you will see the metal element inside is melted.
  4. Optionally, you can use your digital multi-meter to check continuity across the fuse.

1. Check for voltage (12 volts DC) between the output contacts (AC1 & AC2 marked on the control board) ground (any green wire).

CAUTION: This test should only be done by an experienced person familiar with electricity.

  1. Unplug kiln or turn off circuit breaker if the kiln is wired direct to your power supply. If you can not physically be sure the power is disconnected (for instance is you see that the cord is unplugged you KNOW there is no power coming into the kiln) then check the voltage at the power connection pluck with your multi-meter.
  2. Unplug kiln.
  3. Open up the control panel. This will be a little different on each kiln series.
  4. Remove or open the panels that cover the element connections.
  5. Look at internal wiring.
  6. Specifically look at wires going from power connection block to the on/off switch, then to the control fuse, and finally to the control transformer.
  7. Make sure all wires inside control panel are connected.
  8. Look for any burned spots or deteriorating wire.
  9. Look for any short circuits. This might be caused by a wire losing its insulation and touching another component for instance. Typically if there are any short circuits there will be some evidence of a burn on the metal the wire touched.
  10. Look for dirt or foreign material. Some material can be an electrical conductor and could cause a short circuit. Clean out any dirt.
  11. Check all power wires for firm connections.
  12. Pull off and reseat all spade connector connections of power wires to remove oxides and ensure good connection.
Your power relays are one of the most important components in your kiln. They execute the will of the computer controller, giving power to the elements only when requested. These power relays are also mechanical switches which will wear out over time. Worn out relays can be the cause of slow or incomplete firings, error codes (E-1, E-d), etc. Other more obvious signs of relay failure are if a zone is lagging behind in temperature considerably or if you notice an entire ring of elements not heating/glowing. 
The surest way to test your relays is by using a multimeter to check input, output, and signal voltage. If you do not have access to a multimeter you can run a paper test, which will give you some indication of whether or not you have a relay out.
Paper Test: http://hotkilns.com/run-paper-test & hotkilns.com/
Here we will go through the process of testing relays and contactors as well as what to make of any test results. 
  1. Another way to check the relays (or bad elements) is to check the temperatures of each zone by pressing "1", "2" and "3" in sequence and recording the temperatures of each thermocouple at intervals over the length of the firing. If one zone is consistently firing at a lower temperature then you probably have either burned out elements or a bad relay.
  2. If the relay does not make a soft clicking noise when the kiln is turned on try turning the kiln off and on and then restarting the program.
  3. Remove panel.
  4. Set your multi-meter the approximately 24 volts AC. Check the voltage coming into the coil of the Power Relay. You can tell which wires these are because they will be the small wires coming from the control. This test will tell you if you are getting power to the relay coil which actuates the relay. Unless the relay is actuated by the control you will get no output from the power side of the relay.
  5. With panel plugged in and firing check output from Power Relay with your digital multi-meter. The meter should be set to the next highest voltage above 240 volts AC. Output should be approximately the rated voltage of the kiln when it is supposed to be calling for power to the elements.

CAUTION: LIVE ELECTRICITY IS INVOLVED WITH SOME OF THESE TESTS. This test should only be done by an experienced person familiar with electricity.

See this video:

  1. Check voltage across the top center tap and either of the two top taps.
  2. If there is power look for a bad connection between the power connection block and the transformer.
  1. With the power to the kiln off, open the control box carefully and make sure that nothing is touching any of the exposed wires.
  2. Turn the power back on.
  3. Locate the transformer. Most have 3 wires on the bottom of them- the center wire is actually a
    jumper wire connecting the two center terminals, and three wires on the
    top of it- all wires are on one side of the transformer.
  4. Use a digital multimeter to check transformer operation.
  5. Set your digital multi-meter to AC volts, the next setting higher than 240 volts AC (on a lot of meters this is 600).
  6. Check voltage across the top center tap and either of the two top taps.
  7. With the meter you should be able to read 240 or 208 volts AC on the outer two wires at the bottom of the transformer. (These power wires come from the toggle switch and the power block). If there is 240 or 208 volts there everything is good up to the transformer.
  8. Set the meter to read 24 volts AC and look for this on the outer two wires of the 3 wires at the top of the transformer. If there is no voltage there then the transformer itself is faulty and you need to replace the transformer.
  9. If there is no power go further back on the line and measure the voltage. Keep going until you find voltage.
  10. Look for the problem between the point with the voltage and the last point checked that had no voltage.
  11. Replace transformer if you are not getting proper voltage.
  12. If there is proper voltage there then the control is getting the correct incoming voltage and that the board itself is probably faulty. Replace the control.

CAUTION: This test should only be done by an experienced person familiar with electricity.

See this tutorial on how to use a multimeter.

See this video:

INTRODUCTION TO RESISTANCE

The most common cause of kiln slowdown, E-1 messages, and failure to reach temperature is element wear. As your elements age  they generally increase in electrical resistance. According to Ohm's Law, when resistance, measured in Ohms, increases, both Watts and Amperes will decrease, assuming Voltage remains constant. Since Amps and Watts are the measures of current and power respectively, they can be thought of as the amount of juice that your kiln has to generate heat. Obviously if you don't have enough power, your kiln will fire slowly and might not even reach the desired temperature.

INTERPRETING RESULTS

Using resistance, we can tell exactly how much power your kiln has lost over the course of your element's life. For example on an e23T that uses 240V, a brand new kiln section would read about 14.5 ohms. If you measured this same kiln section after several months of cone 6 firings let's say and the reading was 16.5 Ohms, you would know that this section of elements has lost approximately 14% of it's power (16.5/14.5=1.138, or close to a 14% increase). Again, an increase in resistance means decrease in power. A very general rule of thumb is that most people will typically begin to notice some slowdown once you've lost more than 10% of your power. It will certainly vary based on the kiln you have, your voltage, as the types of firing you do. People only doing low fire work will continue to get by on lower power than those needing to go to higher temperatures (cone 6+). As you can see, measuring your element Ohms is the best way to identify when elements need replacing.

Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. How you figure out the section ohms depends on whether the elements are wired in Parallel or Series. Most kilns are wired in Parallel except for JD230V and most 18" kilns like the e18T. For a parallel kiln you take the per element ohms listed and divide by the number of elements per section. Ex. e23T 240V 1 Phase is 28.9 Ω per element with two elements per ring = 14.5 Ω per section.   Ex. 2. JD2927 240V is 36.5 Ω per element w/ three elements per ring = 12.2 Ω per section. See this link for more info on Series vs. Parallel

Here we will show how to best measure your element resistance for two groups of L&L Kilns, into which most models fall.

EASY-FIRE, DURA-FIRE, EQUAD-PRO, LIBERTY-BELLE, DOLL, SCHOOL MASTER

In these series' of kilns a piggy-backed control panel covers up the element terminals.

  1. Turn the power to the kiln completely OFF and unplug it if possible. If it is direct wired, then you should at least turn off all power at the disconnect switch or circuit breaker.
  2. Open the outermost control panel by unscrewing it either from the element cover box in the case of Easy-Fire, eQuad Pro, School Master and Liberty Belle kilns or from the kiln body in the case of Doll kilns.
  3. Once you open up that control panel you will see the element power wire terminal strip. See the picture. It will have numbered wires coming from the element terminal blocks and wires connecting to the power relays. There are two wires per kiln section/ring, so numbers 1 & 2 are for the top section, 3 & 4 for the middle, and 5 & 6 for the bottom section on a three ring kiln.
  4. Set your multimeter to Ohms (Omega symbol Ω) and using your testing leads, place one in between the two tabs/terminals w/ #1 wires connected. There is a small circular divot that the lead fits into (see picture). Put the other lead on terminal #2 and make note of the reading. Repeat the process for 3 & 4 and then for 5 & 6. Remember that each pair of wires represents one section.
  5. Compare your readings to those on the wiring diagram in your instruction manual. Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. See above for more info on understanding the readings.

CHECKING RESISTANCE ON AN EASY-FIRE KILN

JUPITER, DAVINCI

In these series' of kilns, the control panel is separated from the kiln body and the element terminals are connected to the controls via external jumper cords or plugs.

  1. Turn the power to the kiln completely OFF and unplug it if possible. If it is direct wired, then you should at least turn off all power at the disconnect switch or circuit breaker.
  2. Unplug the first jumper cord from the control panel.
  3. Set your multimeter to Ohms (Omega symbol Ω) and using your testing leads, place one lead on each of the "hot" prongs. They will be the flat ones.
  4. Make note of the reading and move on to the next one.
  5. Compare your readings to those on the wiring diagram in your instruction manual. Keep in mind that the ohms on the wiring diagram are per ELEMENT while your reading will be per SECTION. See above for more info on understanding the readings.

See this tutorial on how to use a multimeter.

  1. Check the tightness of all connections. Do this by wiggling the connector to make sure it is not loose.
  2. Examine all connections for any sign of oxidation or discoloration.
  3. Examine all wires for signs that the wire may have burned.
  4. Make sure all wires are connected to their proper connection point. You may have to compare the kiln to the wiring diagram to be sure of this. This step would be particularly important if a wire has come loose.
  5. Look for any place where a wire may have shorted against the metal case or a component.

CAUTION: Turn power off to kiln form the circuit breaker or unplug the kiln.

  1. Try leaving the toggle switch on for 30 seconds without pressing any buttons.
  2. This will give the control time to go through its own internal start-up sequence

This applies to DynaTrol controls made before 2006:

  1. When these older controls are running a program and the toggle switch is turned off without pressing the STOP key first and then the switch is set back to on: the screen will blink and go blank for 10-15 seconds then come back on.

The control board needs to be replaced if:

  1. The transformer is OK.
  2. You know you have voltage going to the control board but the control still shows no display.
  3. You know you have voltage going to the control board but there is no output form the control to the power relays (even if you have display). In this case the little transistors inside the control that regulate output are not functioning).
  1. Unplug kiln.
  2. Remove the four #6 screws that hold the control in place from the front face of the control panel.
  3. Remove the control box and remove the insulation panel.
  4. Pull of the spade connectors from all the connection points on the back of the control. Loosen the screws that hold down the thermocouple wires and pull out the wires from under the screw heads. It is OK to remove the screws if this is easier for you. First not where all the wires go. These are all clearly marked with color coding on the Wiring Diagram.
  5. Pull old control out. Put new control in and screw in place with the #6 mounting screws. Replace wires on proper connectors.
  6. Be careful to get the Red or Yellow of the thermocouple wires to match the colors painted on the control board.
  7. Double check that the proper color coded wire goes to the proper terminal (Orange = OUT, Purple = AC1, Green = CT, Gray = AC2).
  1. Unplug kiln.
  2. Remove the Control Box.
  3. Using a 3/8" nut driver or ratchet wrench or adjustable wrench, remove the nuts that hold the element end onto the Element Terminal Bolt. Note that the terminal bolt head is held in place by an inset shape on the underside of the ceramic terminal block and it will not turn much.
  4. Untwist the element end from around the Element Terminal Bolt. Straighten it out as much as possible.
  5. In most cases the element can be lifted out of the holder at this point. Sometimes, if the element has really disintegrated, you need to remove it in pieces with needle nose pliers.
  6. If element is hard to get out of the holders (because of growth of the element) you can try heating up the kiln slightly so as to heat up the element slightly to just the point where element is slightly pliable–don't let it get red. This will soften the wire. Then turn off the kiln and disconnect all power to the kiln. Using heat protecting gloves and a pair of needle nose pliers pull out the softened element.
  7. From the inside of the kiln, using needle nose pliers, grab the element as close to where it goes through the brick wall to Terminal Block. Pull the element end through the hole. Be careful not to enlarge the hole in firebrick. The brick is soft and will not take much abrasion.
  8. Be sure to check for failure points for evidence of contamination on the element and the element holder. If the element holder is contaminated it will cause rapid failure of the new element. Replace contaminated holders with the new ones.
  9. Using your multimeter check the resistance of the new element.
  10. Install the twisted ends of the elements through the holes in the wall of the kiln. Element ends should be straight at this point.
  11. Pull them up tight up to the wall of the kiln by pulling from outside the kiln.
  12. Lay the element into the groove. Note that the unfired element is going to have some springiness to it before it is fired for the first time. You may need to use a screwdriver to press the element into the holder. YOU DO NOT NEED PINS.
  13. FOR KILNS WITH NON-CERAMIC TERMINAL BLOCK OR ON RETROFITTED KILNS WHERE YOU HAVE ADDED A CERAMIC TERMINAL BLOCK BUT STILL NEED BUSHINGS: Be sure to replace the insulators and spacers over the element tails.
  14. Consulting your picture or labeling, wrap the appropriate element tails around the appropriate element connection bolt, clockwise, one around and cut off the excess tail.
  15. Install the elements and hardware: Place the wires from the jumper cord or connecting wires onto the appropriate bolts and tighten with stainless steel nuts.
  16. A washer goes under the first element.
  17. Twist the first element end CLOCKWISE around the Terminal Bolt.
  18. The next element gets twisted around the Terminal Bolt on top of the first element.
  19. Another washer goes over the Terminal Bolt.
  20. Place a nut on top and tighten it.
  21. Put another washer on.
  22. Put on the Ring Terminal of the Power Lead Wire.
  23. Put another washer on.
  24. Put another nut on and tighten it. How much the nut can be tightened is dependent on how tight the element connection bolt is on the element connection board. A tight connection is very important, but if you tighten too much and twist the element on the bolt too far you could break the element, the bolt, or the insulator.
  25. Reattach the ground wires and the element box if the kiln has them. DO NOT FORGET TO ATTACH GROUND WIRES. IF EACH KILN SECTION IS NOT GROUNDED THIS CAN BE VERY DANGEROUS.
  26. Test the resistance at the jumper cord's plug head or at the other end of the connecting wires.
  27. Reattach the control box, turn on the kiln and make sure all the elements come on.

See this tutorial on how to use a multimeter.

See this video:

  1. Unplug kiln.
  2. Remove the control box and remove the insulation panel.
  3. Remove the wire connectors from the end of the fuse holder on the inside of the panel.
  4. Unscrew the nut that holds the fuse holder in place.
  5. Remove and replace with a new fuse holder. Reconnect wires.
  1. Unplug kiln.
  2. Remove the control box and the insulation panel.
  3. Remove the wires to the relay.
  4. Remove the nuts from the studs that hold the relay in place. Remove old relay and replace with new one.
  5. Visually inspect the wire connectors. Do they look corroded or "cooked"? Are the wires frayed? Any corrosion on the wire itself? If any of this is questionable you should replace the appropriate wires.
  6. Reconnect all wires. Visually inspect to make sure the spade connectors are down as far as they can go and feel to see that they are tight (a gentle tug should not remove one). If they are loose for some reason remove the wire and slightly squeeze the spade connector with pliers to tighten it.
  7. See this video.

IMPORTANT: The slip on wire connectors cannot be loose or corroded. If there is a bad connection then heat will be generated and the component that they slip onto (relay, terminal strip, etc) may overheat and fail. If you squeeze the slip on terminal to make it tighter–be sure to squeeze it evenly so that one side is not tight and the other loose. If there are any doubts about the integrity of the wire or the connector replace the whole wire or harness.

  1. Unplug kiln.
  2. Remove the control box and remove the insulation panel.
  3. Using needle nose pliers pull of the wires from the transformer. It can take significant force to remove the spade connectors.
  4. Unscrew the two nuts that hold the control transformer onto the panel and remove the transformer.
  5. Before installing the new transformer put the small jumper wire onto terminals #2 and #3 on the bottom row of terminals. Note the little numbers by the contacts.