Winnie Coggins on thu 7 sep 06
For my past 2 Cone 6 firings in 3-ring (Thermocouples in each ring)
electric kiln using the Dynatrol slow glaze pre-programmed schedule, my
23 inch diameter kiln has fired normally until 1915 degrees F at which
point the controller held the temperature (with much clicking of relays)
until finally turned off 1 and 1/2 hours later. Error codes were on,
but no error messages. Temp varied from 1915 to 1908 on each ring over
the 1 1/2 hours.
I'm trying to trouble shoot the problem and feel that since it was
repeatable, it is likely the controller. My thermocouples and elements
seem fine. What am I missing--are parts other than the keypad
(motherboard) likely to be involved? Thermocouple wires? relays? The
inside of the controller box looks "normal", no signs of hot spots.
Winnie in Columbia, Maryland
jwcoggins@comcast.net
dwichman@frontiernet.net on thu 7 sep 06
Just an idea based on my experience with the same issues...
The elements in my kiln had to be replaced... the way the kiln was
firing caused a large difference in each thermocouple reading and the
Dynotrol has a setting which throws an error up if the difference is
more than a range of preset degrees. There was very slow or no degree
increase for a while until the thermocouple readings sent to the
Dynotrol had the preset difference, then the error message was
displayed. The error message can be looked up in the Dynotrol Manual.
There is also a way to read what each thermocouple reading is. It
really helped to figure this out (With the aid L & L's Rob Battey) and
it also helped to figure exactly what the offset and firing set temp
should be after the new elements were installed.
Debi Wichman
www.elementterra.com
Rob Battey on fri 8 sep 06
Hi Winnie,
One of the lines we can draw on the issue of whether to replace the
controller or not, in any kiln troubleshooting situation, is how the Error
codes behave. If the Error Codes are turned on, and the kiln just sits
there climbing less than 12 degrees per hour on all three thermocouples for
more than 22 minutes, and no Error Code appears to turn the kiln off, then
the control is may well be unsafe to use and should be replaced.
I rarely if ever hear of that sort of behavior from a newer control, but
sometimes older electronic controllers (I believe yours is from around
1999) can exhibit abnormal behavior because their components are not quite
as robust as the ones used in electronic controllers today. The newer
controllers have better electronic noise immunity built into them.
Sometimes a control like this will stall at a temperature and that can be
due to a number of factors. If the thermocouple wires were overheated
against the kiln or loosely connected to the thermocouples, if high voltage
wires run too close along side of low voltage circuits (like thermocouple
circuits), or if the relay contacts are excessively dirty then you could
create electronic =91noise=92 or =91electromagnetic interference=92, and thi=
s can
sometimes make older controllers act in unpredictable ways. Once the
control has been acting this way it usually needs to be replaced, just
changing the relays or thermocouple wires seldom fixes it. The new
controls used today on kilns are much tougher and are not as affected by
electronic noise.
Hope that helps you Winnie
Rob Battey
Technical Support Manager
L&L Kiln Mfg., Inc.
rob@hotkilns.com
Arnold Howard on tue 12 sep 06
For a nominal fee, Bartlett Instruments might be able to
refurbish the controller that had the error message.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
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