tomonish

Thank you for your reply. I think buzzing noise is coming from the control box. but I cannot locate exact spot which is causing the noise. I don't know if I should call the electrician first or kiln technician....?

I have an old Orton Autofire 3000 which throws FTH (fail to hear) error code and have problem heating. Elements are not in perfect conditions but it could heat up to 1230 (cone 6) without problems 3 firings ago. When it first had the same problem (temperature was fluctuating and/or dropping, or fail to heat), we changed the thermocouple and fixed the problem. I did 2 firings without any problems with new thermocouple and now having problem again. When the kiln have this heating problems, it makes funny buzzing noise and the light bulbs in the house starts flickering. Even though it shows on the AutoFire display that elements are on, but temperature doesn't go up or it goes down, and eventually throws the FTH error code. We've checked relays and all the connections, and they seem to be fine. Is there any suggestions? Can it be a power supply issues? Any help will be much appreciated!