Monday, March 05, 2012

Kiln Maintenance -- Relay Replacement on a Paragon SC-2

The day was bound to come when my Paragon SC-2 kiln would need some maintenance. I got a bit of warning that there was trouble coming when I started to hear a whining noise after the cycle had completed (after the regular beeping completion alarm). Eventually, I got the whine during the cycle, turning on and off as the relays clicked. When I called Paragon service, they suggested it might be a relay nearing failure, so I ordered a replacement to have at the ready. Then I decided to replace it immediately, as I read stories of the relay failure leaving the kiln full on to maximum temperatures. No melted silver for me, please!

The relay is the part that opens and closes, giving a clicking sound, to allow electricity to flow to the kiln heating elements. By turning the elements on and off in varying proportions, the kiln can adjust to any temperature. Relays have a limited lifetime, with only so many clicks in them. Failure is guaranteed, eventually. The failure may be either in the open or closed state. If open, the element fails to heat. If closed, the element can't turn off. For larger kilns with more than one element, losing a relay can be somewhat compensated for by the computer brain and the other elements. But with only one element on these small kilns, there's a potential melt down risk, with a total loss of glass or metal work inside the kiln. That's a risk I decided to avoid, thanking the kiln gods for the early warning.

The relay arrived with no instructions, so I started a web search to find out how to do it. The Paragon kiln instruction manuals are all online, including the SC-2 manual. The manual has detailed instructions for replacing the relay, with plenty of photos. If you're a visual learner, you may prefer the video demos available at Cherry Heaven. In either case, be sure to unplug your kiln before starting any repairs. As well as relay replacement, there are instructions on both sites for thermocouple and controller replacement, as well as lots of other helpful details such as programming instructions. Read more about relays in kilns on the excellent Paragon blog.

After all this research, I decided to make my own slideshow/video (a learning process in itself), and recruited my son to take photos for me during the ten minute procedure. Perhaps it will convince you that this is a simple process that all kiln owners can manage on their own.