Oven not used for a while, now bottom heating element does not turn on but relay seems ok

[sridharrajagopal]

Hi,

I hadn't used my Controleo3 oven in a while, and turned it on and ran a reflow cycle to warm things up. It failed because the temperature deviation was greater than 20 C (don't remember the exact error thrown).

I tried to test the various heating elements (I have 3 - bottom, top and boost element), and saw that the bottom element does not turn on, while the top and booster were ok.

I ended up opening up the oven to inspect the relays, which I thought may be the culprits. I turned on individual heating elements from the Controleo Settings->Testing menu, and while the top relay and the boost element relay came on (their LEDs turned red AND I was able to see the elements heating up), the bottom element relay did not turn on (no red LED, and heating element stays cold).

However, I can turn on the bottom element relay by manually applying a DC voltage to the relay to trigger it, so the relay itself seems to be ok. It appears the issue may be the signal from the controller?

I was wondering if anyone has run into a similar issue before. I recently came across my PocketChip being dead after a long period of inactivity and saw that it was due to NAND degradation and I can to reflash the board to use it. I wonder if a similar issue may exist here (though the controleo booted up fine and also ran the reflow profile. I can try updating the Controleo3 firmware and see if it fixes the issue, but I wanted to raise the issue here for feedback and input.

Thanks,
Sridhar

[sridharrajagopal]

I had never heard of Arduino sketches degrading over time, so I was skeptical of that being an issue, but I thought I'd mention it nevertheless above. As expected, reflashing the new firmware (I was using 1.4 before and upgraded to the current 1.5) fixed nothing. Output 1 still wasn't turning on.

I ended up switching the bottom element input from output 1 to output 4 (4, 5 and 6 were being unused), and sure enough, output 4 worked just fine and it turned on the bottom heating element just fine.

It's a little puzzling as to how and why output 1 on the controller board would go bad, but at least I have a resolution now, as I had 3 unused outputs luckily to choose from. If anyone can shed a light on how it may have gone bad, it would be helpful for others in a similar situation.

Thanks,
Sridhar

PS - Now comes the not so easy part of trying to close up the oven's top sheet metal cover. I already have a cut, so I'll resume after some bandaid! 😊