Induction range stopped working - need help

[Techie1961]

I have a Kitchenaid induction counter top range that is about 4 years old. We had a power outage a few days ago and it won't power up anymore. I have an Eaton whole home surge protection on the box and both lights are still on after the outage. I opened it up and one fuse was blown. Changed it and powered it up again and the fuse blew again. Opened it up further and there is a filter board on it with a blown varistor. We are looking into warranty but doubt they will cover this. Might have to go with the surge protector warranty.

Further details - when the power was off, I hooked up a generator but before connecting it, I turned off all of the 230 volt 2 pole breakers so it was only lights fridge etc. Once the power came back, I disconnected the generator, turned on the main power, and then each 2 pole breaker (stove included). That's when we noticed the display on the range was dead.

The photo is of the varistor that blew. I thought about getting just the varistor and trying to replace that. The board is $180 and two weeks delivery.

Anyone know much about these?

 

[404]

Does the second varistor have a part number on it?

 

[Techie1961]

Does the second varistor have a part number on it?

It does and the board for the other two burners is the same. It is a Q14K275. The thing that has me puzzled it that the one side seems fine and they each get fed with a separate fuse and it didn't blow. Why would the varistor blow is the first question and then why would the display be dead and not power up. Maybe the display is fed from one side only.

 

[ratman2]

It does and the board for the other two burners is the same. It is a Q14K275. The thing that has me puzzled it that the one side seems fine and they each get fed with a separate fuse and it didn't blow. Why would the varistor blow is the first question and then why would the display be dead and not power up. Maybe the display is fed from one side only.

The display WOULD be fed from one side only....they use 120

 

[Rookie2]

A blown varistor should be open. If you are still blowing fuses ,you have something more serious wrong. Try unplugging the burners or measure the resistance and compare to the good side .

 

[Techie1961]

Thanks for your responses. When I first tried to get it working again, I put in a new fuse. When I turned the breaker back on, there was a pop (my wife heard it) but I was in the basement when turning the breaker on. I thought that it was likely the fuse popping again but yes Rookie, the varistor would be open wouldn't it. Now I am thinking that the varistor must have blown with the new fuse.

I'm thinking Ratman that the control board is likely low voltage supplied by one of the inductor control boards. There are connectors on both boards that go the control PCB and likely one of them only is being powered like you say.

I'm struggling with the decision on how deep to get into this. The store's repair department is closed today so we will call them on Monday. ***** not having a stove though. I picked up a small one pot induction portable range to keep us cooking for now.

 

[nehog]

This should be a trivial fix... Varistors are common, easy to get. They can fail shorted, but that is unusual. I've seen it, usually only happens on a catastrophic situation.

You can, if you are willing, snip it and use the stove, just hope there are no surges!

 

[MBfreak]

The varistor has probably clipped a voltage spike, until it blew and became an open circuit. The voltage spike has then got into the electronics.
The most expensive part in that is the drive IGBTs that forms the power output part in the HF ( appr 100 kHz) multivibrator that feeds the induction coils.
The IGBTs usually selfdestruct on overvoltage by becoming a short circuit.
They sit on the big heatsink. A quick ohm check can be made. Use a DVM on diode check range. There should be NO lowohm ( < 100 Ohms) readings between the source and drain. Trace the PCB , the source and drain pins are connected to the fat copper traces , the gate will be to a much thinner trace.

Best regards

Ola

 

[Rookie2]

The varistor has probably clipped a voltage spike, until it blew and became an open circuit. The voltage spike has then got into the electronics.
The most expensive part in that is the drive IGBTs that forms the power output part in the HF ( appr 100 kHz) multivibrator that feeds the induction coils.
The IGBTs usually selfdestruct on overvoltage by becoming a short circuit.
They sit on the big heatsink. A quick ohm check can be made. Use a DVM on diode check range. There should be NO lowohm ( < 100 Ohms) readings between the source and drain. Trace the PCB , the source and drain pins are connected to the fat copper traces , the gate will be to a much thinner trace.

Best regards

Ola

I love GJ , there are so many great minds out there !

 

[404]

Schematic by OP shows stove fed by line 1 and line 2
No neutral only a ground
So all of it runs from 240 including the display

 

[Techie1961]

The varistor has probably clipped a voltage spike, until it blew and became an open circuit. The voltage spike has then got into the electronics.
The most expensive part in that is the drive IGBTs that forms the power output part in the HF ( appr 100 kHz) multivibrator that feeds the induction coils.
The IGBTs usually selfdestruct on overvoltage by becoming a short circuit.
They sit on the big heatsink. A quick ohm check can be made. Use a DVM on diode check range. There should be NO lowohm ( < 100 Ohms) readings between the source and drain. Trace the PCB , the source and drain pins are connected to the fat copper traces , the gate will be to a much thinner trace.

Best regards

Ola

Thanks MBfreak, I will have a look at them based on what the warranty issue comes out as. My limited electronics experience can get me through that at least.

Schematic by OP shows stove fed by line 1 and line 2
No neutral only a ground
So all of it runs from 240 including the display

Thanks again 404 for helping me out.

 

[Worsedog]

Since you'll get no professional joy locally today, I'd remove the blown varistor form the circuit and try it out. It cost nothing and might turn into a cheap diagnosis and easy repair if the varistor is shorted causing the fuse to blow.

 

[Techie1961]

Since you'll get no professional joy locally today, I'd remove the blown varistor form the circuit and try it out. It cost nothing and might turn into a cheap diagnosis and easy repair if the varistor is shorted causing the fuse to blow.

I'm tempted but if I do that and there was a warranty, I might void it.

 

[MBfreak]

Hi.
Regarding repairs to your own stuff. I am ALL for it, and have been since I was five. Interest, a sense of self reliance, bare need . Read up on Matthew Crawford " Shop Class as Soul Craft" and also Sennet " The craftsman "

Some repairs are harder than others, and when it comes to electrical and software repairs a certain amount of theoretical knowledge is needed. A lot of that can be had by trying to understand even how simple parts work, and by textbooks from technical college. It is an exponential learning curve.

The biggest obstacle from my point of view is the propensity of manufacturers to lock away documentation behind layers of Fort Knox like " service centers".
Where many of the employees are badly paid, not very well educated and/or trained and work under poor management. Most jobs are " that board usually blows, put in a new one. $ 450 please" Ie , planned breakdowns, sell the c-p twice during its rather short lifespan.

So, any site that leads to service manuals, data sheets and schematic diagrams are high on my list.

Regarding waranties. I seem to recall there was a member on GJ that had the handle " I void warranties" . I am of the same bent. 69 yo and learning every day.

Best regards

Ola

 

[westom]

The photo is of the varistor that blew. I thought about getting just the varistor and trying to replace that. The board is $180 and two weeks delivery.

Among the many reasons for a failed varistor is how the generator was connected so as to create a open neutral. Nobody can say specifically why that varistor blew due to so little information. For example, details on how that generator was connected and removed are critical. However, you may have created something exceeding 180 volts on one (120 volt) AC phase. A voltage that high for too long (seconds) would explain that damage.

 

[Techie1961]

Among the many reasons for a failed varistor is how the generator was connected so as to create a open neutral. Nobody can say specifically why that varistor blew due to so little information. For example, details on how that generator was connected and removed are critical. However, you may have created something exceeding 180 volts on one (120 volt) AC phase. A voltage that high for too long (seconds) would explain that damage.

I'm pretty careful with stuff like that. When I use the generator, I shut off the breakers for all of the double pole stuff before I even hook up the generator wires. One day I will get a breakout panel for it but for now, lot's of care used. I always shut off the main, shut off all of the non-essentials, connect the generator, use it, disconnect the generator, turn on the mains, turn on the non-essential breakers. In that order.

 

[Techie1961]

A little update. It turns out that we bought the extended warranty for the appliances when we bought them. Yay! They will be here this afternoon to check it out. For now, we have a little counter top burner to keep things cooking.

 

[westom]

I'm pretty careful with stuff like that. When I use the generator, I shut off the breakers for all of the double pole stuff before I even hook up the generator wires.

If generator wires are not hardwired or via specially designed connectors, then woefully insufficient caution exists. Humans are by far the biggest resaon for such failures. Hardware must always exist so that even the most careful human does not make a mistake.

An implication is that wires were clipped on. Not connected via hardware specifically designed only for that purpose. That would explain damage from an open neutral. A problem you would not even know you created. It explains excessive voltage that caused an MOV to short.

Second, if protecting linemen by only tripping a main breaker, then consider this. Any problem or mistake means you should be prosecuted for manslaughter. A felony. That is no different that routinely running stop signs with contempt. Using a main breaker to disconnect your generator from mains is completely irresponsible. Normal is for the most careful human to make mistakes. And for other humans to also make potentially deadly mistakes because one violates acceptable procedures.

 

[Techie1961]

If generator wires are not hardwired or via specially designed connectors, then woefully insufficient caution exists. Humans are by far the biggest resaon for such failures. Hardware must always exist so that even the most careful human does not make a mistake.

An implication is that wires were clipped on. Not connected via hardware specifically designed only for that purpose. That would explain damage from an open neutral. A problem you would not even know you created. It explains excessive voltage that caused an MOV to short.

Second, if protecting linemen by only tripping a main breaker, then consider this. Any problem or mistake means you should be prosecuted for manslaughter. A felony. That is no different that routinely running stop signs with contempt. Using a main breaker to disconnect your generator from mains is completely irresponsible. Normal is for the most careful human to make mistakes. And for other humans to also make potentially deadly mistakes because one violates acceptable procedures.

Full of judgement without knowledge aren't we.

 

[westom]

Full of judgement without knowledge aren't we.

Was the generator hardwired so as to avert overvoltages by floating neutral? Please post facts; not emotions. If you used the main circuit breaker to protect linemen from your generator, then just be honest and say so. If you did not hardwire that generator, then just say so. Then a varistor failure can be explained.

A cheapshot reply implies you did use the main breaker as the only disconnect. That action is so totally irresponsible that one would then post, "I did not realize that it was so wrong and I will never do it again."

Or state how you kept the generator disconnected from AC mains. Then we move on to other suspects in an adult, logical, and responsible manner.