Our bread maker suddenly stopped working. It seemed that the motor will not turn to mix and knead the dough. Unfortunately this one is a couple of years old, and the product seems to be discontinued and is no longer supported. Additionally there are no support available from the manufacturer at all. There are no troubleshooting tips, no service manuals, and no spare parts.
This also happened during the COVID19 pandemic so most businesses are closed in my area, and buying parts and hardware is not really much of an option right now. What else can one do other than trying to take this apart and see if it can be fixed.
I was fully prepared to use an Arduino board to drive the logic if needed and repair or reconfigure the power component if I had to. After a couple of weeks of frustrating troubleshooting (mostly due to inadequate access to right tools) I tested every component on this, except the motor. I had to figure out how everything is connected and works.
The most of frustrations were due to not having the proper multi-meter. I have a MasterCraft brand from Canadian Tire that showed all of it’s inadequacies during this project. The multimeter I had at hand is simply not good for electronics work. I had to put the leads at two test points and try measuring several times at the same test point, on every range until I get the correct reading. The Mastercraft multimeter does not simply tell you if the component is actually open circuit, or the reading is simply out of range of the currently selected mode. If you are planning to test any board you are better off with auto-range multimeter and it will save a lot of time and frustration and will not be getting inconsistent results. The multimeter I had to use looks like this:
Luckily it seems they no longer sell this model. I have two of these from many years ago and they rarely get used. Every time they have been giving me trouble. Most times I install a new 9v battery and 4 weeks later I turn it on for second time to find out the battery low indicator is on and the screen is fading. These are just garbage and for the sake of your own sanity please avoid these. Anyways, I had ordered a new multimeter from Amazon some time ago that conveniently arrived on the same day, exactly an hour after I finished repairing this!
It turns out that the power control board and the logic boards were OK as far as I could tell. I was getting 110v going to the motor pins. I was also getting proper signals that I thought should be there well. Unfortunately the only component that was suspect was the motor itself.
I have included the schematic I drew while I was working out the circuit in case anyone else may needs this. I cannot guarantee its accuracy, but this is as far as I could test with limited tools I had at hand.
The unfortunate part is that the motor is riveted together and cannot be opened easily without the risk of it falling apart completely. I let it sit for a few days, but then since I had nothing more to lose I decided to take the motor apart and figure out what is wrong with it.
I was also dreading to take the motor apart because I was puzzled about what kind of motor it was in the first place since the readings from my not-so-good multimeter were erratic. It was showing open circuit on the black wire and short on the white and red, then I test again and it was showing open on all wires. It was really strange. the only indication was that this was definitely a 110v 60Hz 100W motor from the marking on it.
I took the motor out and used a hammer to take out the rivets. The rivets are soft metal, so I placed a nail on the end of the rivet and “un-riveted” the rivet without too much damage. I was not sure if the rivets can be used again or not at this pint.
It turns out the motor is an induction motor. This was good news to me since these are very reliable and easy motors to work with (from my perspective at least).
After I started to take the motor wire assembly apart I found a 250v, 10A fuse that was soldered in-line with the black wire and shoved into the casing of the motor where it cannot be accessed or seen from outside and without taking the motor apart. the fuse was definitely open circuit now, so I replaced the fuse with another 250v 10A fuse I salvaged out of a dead power supply I had lying around and it solved the issue.
For putting the motor back together, I used the same rivets. I used my vise to push the parts together and fed the rivets through the holes, then used the largest Philips head screwdriver and hammer to gently fold the rivet back into shape. I would have used another solution such as a nut and bolt instead, but again, due to the pandemic I didn’t have access to anything outside of what I had at hand at that time.
The issue might have been caused by some water and flour getting into the bearing for the mixing blade and causing excessive friction (and thus causing the fuse to burn due to motor pulling more current). The solution is to take a bit more care when cleaning the bread maker bin and to always make sure that the blade can turn freely by hand before inserting the bin in the machine and starting the program.
I also installed the new fuse outside of the motor with connectors, so if the fuse burns again I can simply disconnect it and replace it without having to breaking the rivets and taking the motor apart.