This is a followup to the previous article on the Kleenmaid TO500X Designer Multi Function Electronic Timer Oven. Remember that after the repair, it was working, but after baking a set of frozen pies on one weekend, the next weekend – it stopped working again. The symptoms were different this time. The oven lights inside will work, but no heating or fans would operate. I thought at first that it was the thermostat, since this controlled the power to the heating elements in order to turn them off to maintain a set temperature.
I switched off the power, and checked that the thermostat was in fact … working, just like last time I checked. Ok, so scratch that idea – what else could be wrong. Eventually after some thought and research, I was reading the oven operation manual, which suggested that on some models, there was an oven door switch which would cut the heating if the door was opened. Yes, this oven did have a door switch, which used to cut off the heating when the door opened, but I remember that recently it had not been stopping the heating. There is a red indicator light that shows when the heating elements are on, and in the past – this went out when the door was opened, but in the last few months, it seemed to not go out. Maybe this could be the reason.
So, open up the housing and locate the door switch that was on the left side, check for continuity, and nothing – even when the button was pressed all the way. This had failed so checking for a replacement – Metalflex MS-385 seems a common part, but this one was shaped differently. The local oven parts stores didn’t seem to show this as a spare part – so maybe I can just bypass it, like I did with the relay.
After I had written the previous article on this oven, I remembered reading that this particular model would disable the power if the clock was not set – as a fail-safe. By applying the power and setting the clock, I could hear a click from the clock area. Perhaps the relay was now being turned on. But then – how to explain the previous problem? Unless the door switch had decided to become intermittent, and sort of arc’ed over – maybe the timer electronics detected this as a fault and cut the relay.
I had tested the clock board and controller out of the housing and had not been setting the clock, so the relay would not have been turned on. Bypassing the relay would allow the power to be available independently, so maybe the relay is working again, after a power reset. To test this hypothesis, I decided to remove the bypass on the relay and just have a bypass on the door switch.
I reassembled the door switch mechanism and then closed up the oven, and went and replaced the fuse that I had pulled out in order to remove power to the oven. The oven clock was now blinking and after setting the time – a couple of seconds later, I heard a click which could have been the relay turning on. I used the control to turn on the light, and the light came on – fantastic. Selecting the fan, and yes – the fan would spin up. Next, turn the thermostat, and the thermostat indicator light came on – meaning that power was being applied through the thermostat.
Well that is good, I have a working oven again – except that the door switch is no longer operational – but it was an optional feature anyway, which helped for safety – but most of these ovens don’t have one. It looks like this oven is now repaired, again – and hopefully for good. In the meantime, I will see whether I can locate a suitable replacement switch to restore its full function.