Oven model KitchenAid KEBS107 DSS 10
Short Version (TLDR)
The short version of this story is I re-soldered resistor R1 on the control board and everything seems to work fine now.
How did I know component R1 was bad? When I touched it with my finger, it wiggled back and forth – it was evident the solder joints had failed. All of the other components seemed to be okay, although many appeared to have been running rather hot over the years.
Backstory
My KitchenAid wall oven has been working intermittently for some time, and recently decided to stop working altogether. In the past few months, it seemed to stop working periodically with no warning; or it would just cut out (even when it was not in use) and show the PF error (Power Failure).
In my mind, all of this pointed to some sort of loose wire or failing component on the circuit board. I’m not real good with circuit boards, but I have a bit of experience with them…and can spot a burned component, so with that bit of confidence I decided to attempt a diagnosis and perhaps a repair.
Internet research provided very little help. Usually the diagnosis was “replace the control board”…well, if I do that, I might as well replace the entire oven. The prices on boards were $250-$600 and we purchased the oven second hand several years ago for less than the current price of a replacement board, so instead of investing in a control board and crossing my fingers that it would solve the problem, I’d rather just find an “open box” oven or return at one of the big box stores and have a new oven with a warranty. But what I most wanted to do was to NOT spend $1000 (or more) on a new oven…and, if possible, keep this oven out of the landfill. Can you tell that I’m frugal? I tend to like my money and prefer to keep it in my pocket if possible (I’m generous too, but I have to have money to be able to be generous, so why purchase another oven if I don’t have to?).
Repair
First, I shut off the power at the breaker and checked for power at the oven using an inductive probe. The power cable supplying electricity to my oven is accessible in the cabinet under the oven, so I just held the probe near the cable and it didn’t beep, which made me feel confident that the line was not enbergized. This video shows how to use an inductive current tester, similar to what I used.
I then opened the electrical junction box in the cabinet and disconnected the oven eletrical wires by removing the wire nuts, which released the wire and the flexible conduit that connected to the rear of the oven. This had to be done because the conduit/wire acted like a short tether, preventing the oven to be fully removed from the wall cabinet. This video shows how to wire a junction box for an appliance.
Please be aware – electric ovens operate on 240VAC which is enough to kill a person – so I had to make certain the power was off. If I had been unable to confirm the power was off, then I would not have attempted this repair. Instead, I would have hired a qualified electrician or technician to make this diagnosis/repair.
Once the power was off, I opened the oven door and removed the screws holding the vertical trim on either side of the oven (one short screw on each side near the oven door hinges). After removing the trim by pulling down and then out, this exposed two more screws (one on each side) that hold the oven to the wall. I removed those screws. This video shows the location of the screws.
At this point the oven was able to slide out of the cabinet, but is rather heavy and bulky, so I employed the assistance of my son and the two of us pulled the oven out and set it on the kitchen counter (we placed a piece of corrugated cardboard on the counter to prevent any scuffs from occurring to the countertop). So far, so good.
The next challenge was to remove the top and back covers from the oven. There are several sheet metal screws that hold all of this together. I removed each screw from the top and placed it in a specific location so I wouldn’t lose them or get them mixed up with the other screws. I did the same with the rear panel, keeping the screws separate just in case they were different. Fortunately for me, all of the screws were the same.
In the top of the oven was the technical troubleshooting guide. The paper was brittle from age and heat. The scanned pages are at the end of this post, but there was nothing in the guide that assisted me with this repair.
Although this repair only required removing the top to gain access to the control board, I saw on YouTube where a gentleman checked a thermal switch on the rear of the oven, and that switch is under the rear panel, so I removed the panel, checked the switch (which was working fine, but it was missing a screw, so I added that screw) and then replaced the rear panel.
The control board is at the front of the oven held on with five screws. Looking at the components I could tell that many had been running hot for some time – the brown streaks going up (against gravity) indicated that heat and/or dust had been at work for several years.
I touched each component to see if it was secure and intact. The large resistor, R1, caught my eye and when I pressed on it, I could feel how loose it was. No other components were loose. Evidently the heat generated by the component in such a warm environment caused the failure of the solder joints and perhaps the circuit board traces.
I removed the ribbon cable by releasing the connector - on mine I had to pull up on the outer-band of the plastic connector. I had to be careful with this because the ribbon cable is just a strip of plastic with copper strips embedded in it (connecting the oven keyboard to the control board). The other connectors were more difficult to remove and the connectors with the heaviest wire did not release, so I left them connected and just made my repairs while the board was attached to the oven.
I removed the five screws that held the board to the front, being careful to not lose the spacers holding the board away from the oven face. Also, the displays are plasma, which are made from glass, so I had to be very careful to not break them. A crack in the glass and the display will go out (why don’t manufacturers just use LED/LCD displays?).
Now here’s the tricky part: one lead for R1 is at the top of the display (fairly easy to access) and the other is under the display (virtually impossible to access). I tried just resoldering R1 and that worked on the lead under the display (I was able to get the tip of the soldering iron to touch the lead of R1 and dab a bit of solder on it; I also tried to add some solder from the component side).
On the lead that was easy to access I attempted to resolder it without success – R1 still moved. Using a simple multimeter on the ohms (resistance) setting, I determined where the leads of R1 connected to – the top lead connected to the first pin on the display. With that bit of important information, I took a short length of wire, bent an eyelet in one end to go around the R1 lead, and bent an “L” in the other end so it would lean up against the first leg of the display (no photo for that, sorry). Then I removed the solder from the R1 lead with a solder sucker (a hand operated vacuum device – some copper braid would likely work as well), and the placed the short length of wire in place, and soldered both ends – the eyelet end soldered to R1 and the “L” soldered to the display leg. Then I dabbed a bit of solder on the component side of R1 (in the unlikely event that this is a multilayer PCB). I checked for a solid mechanical connection (no wiggles) and then placed an ohmmeter on it – the continuity seemed fine. It seems we had success.
After that I buttoned it up – reattached the control board to the face of the oven (spacers and five screws), plugged in all the connectors, vacuumed the dust from the top of the oven, placed the tech sheet back in the top, reinstalled the top and the back panels. Then I rousted my son to help me lift the oven back into the cabinet hole, and reconnected the cables/wires. Flipped the breaker to the on position, everything seemed to work fine. So we shut off the power, finished screwing the oven back in the wall, replaced the trim pieces, placed the cover on the junction box, and reapplied power. It still worked – yea! I set the oven’s digital clock, cleaned up my mess, and enjoyed an adult beverage to celebrate keeping another appliance out of the landfill.
Now, with all that being said and patting myself on the back, I do realize that it is highly likely that the control board will fail again in the future – it is exposed to too much heat and the components are likely to fail when the ambient temperature they are exposed to while the oven is operating is 120F-200F. It’s just a poor design by the manufacturer . . . and I suspect that with a bit of engineering the oven could be designed to either (a) keep the board a bit cooler or (b) use oversized components on the board so they will last longer in this harsh environment. I realize that goes against planned obsolescence, but it would create less waste in the landfill. Honestly, I wish I could find an oven with knobs and mechanical thermocouples rather than this electronic crap we seemed to be forced to purchase today…just my $0.02.
Cheers!
Tech bulletin found in oven
