My electric oven is broken. Nope, it's not the element. :(

[phucheneh]

I believe we have some home repair gurus in ATOT, so I figured I'd run this by you guys and see if someone can point me in the right direction...

Kenmore (yeah, I know, they don't make a damn thing) electric range, P/N 790.96020400 (or 790.9602x400...I think the variable is just for different colors). Pretty standard flat top all electric 220v range. Knobs for stovetop, digital display for oven.

We were having some trouble with some bad breakers in the house, which are supposedly now fixed (old house, really needs a whole new box...whole other topic there). Never had symptoms from the stove, though, just some flickering from the 110v appliances on a different circuit. So I dunno if this is just coincidence or what.

Anyhoo- The range powers on and everything on the display/controls works (responds to user input). But the heating elements in the oven never come on. The burners on top work fine.

I can hear the standard relay click when you turn the oven or broiler on. But nothing happens. Oven/preheat lights come on; that's it.

All the wiring appears to be fine. I've checked continuity into the control board; both 110v feeds are getting to where they're supposed to go. The heating elements (wired in series, bake output should turn both on, broil only does the top) seem to be fine. Nothing visibly wrong, not grounded out, and both read about 20 ohms when checked with a DMM.

The outputs on the board are labeled bake, broil, and L2 out. I got no juice on them.

Seems to me that the controller is about the only option. Dr ATOT, do you concur?

 

[phucheneh]

Oh, I also was suspecting the temp sensor. It's got a little two-wire thermistor.

But I would think if that was not reading the right temp, the lights indicating that the oven is on would not be lighting up. FWIW at room temp it's right at about 1000 ohms (don't know if there's a chart for temp coefficients somewhere).

I do have wiring diagrams, which were taped to the back of the oven along with a parts diagram...I'm guessing you're supposed to remove those. But huzzah for fire risk, as they would otherwise be lost.

 

[LTC8K6]

Do you have the 220 present for the elements?

 

[PowerEngineer]

Do you have the 220 present for the elements?

A good question. I suppose it's possible that electrician could have inadvertently made changes that disconnected your 220 service. You might first check the voltage at a 220 outlet (I have one in the garage).

My other suggestion for you is to disconnect and reseat all connectors to and from the controller. I am also afflicted by a Kenmore oven (made by GE); mine rather regularly loses connectivity between the front panel switches and the controller (and decides to try to turn itself on!). Reseating the ribbon connector fixes the problem -- for another six months. (The replacement front panel is $750!) My Kenmore dishwasher has a similar problem.

Good luck!

 

[MonKENy]

sounds like maybe the 220 blew on the breaker? 220 goes to heating elements 110 goes to everything else, lights etc

 

[phucheneh]

I've checked the outlet; I've got 220v going in, for sure. I've had it plugged in with the back panel off to confirm full voltage into the control panel. Nothing comes out, though.

I was going with the 'half of my 220 is dead' theory, as well, but the wiring diagrams seem to indicate that the burners (which are working normally) are 220, as well.

The relay is right by the spade terminals with the wires that energize the heating elements, which is why (to me) this seems really weird...not much room for anything to fail.

I will try pulling the panel out to look for scorch marks or such on the other side, and check all the connections. Up to now, I had been trying to avoid it because it looks like a stiff breeze might break it.

edit: oh yeah, a great page for Kenmore owners-

http://www.appliance411.com/purchase/sears.shtml

Turns out this is a Frigidaire oven. For some reason, that amuses me.

 

[phucheneh]

Well then...

Since I couldn't find any other issue, I went ahead and spent a few minutes delicately releasing the control/input boards from their cheap plastic housing.

This is what I saw from the back when I initially removed the back panel for the oven and starting checking stuff out as described above. I mean, it LOOKS fine...no signs of arcing or excessive heat...


Let's just turn this bad boy over so we can double check on the green side...

OH GOD-FUCKING-DAMMIT.

OVEN, FOR THE LOVE OF GOD, WHAT DID YOU DO TO YOURSELF?!

 

[LTC8K6]

That'll do it...

That could have been from an intermittent outlet wiring problem.

 

[phucheneh]

Could it? I wasn't really sure what might've done it. I would figure you would need a serious surge to do that.

Is there DC conversion for the burners/elements, or do they get fed AC? I'd just follow the traces, but I can't see them. D:

 

[Engineer]

That will buff right out! :biggrin:

I think its dead Jim. /Bones

Well, that does it. I'm going back into my dead big screen TV and pull the boards and check their back sides now. Something is burnt (and still burning) and I can't find it....maybe the back side is a clue....

Good luck on the oven. Looks like a new board is in order (unless you want to replace the relays or whatever the hell the black stuff "was").

 

[Red Squirrel]

Well THERE's your problem. :awe:

That one relay, yeah, that one... it's in backwards.

 

[PottedMeat]

Could it? I wasn't really sure what might've done it. I would figure you would need a serious surge to do that.

Is there DC conversion for the burners/elements, or do they get fed AC? I'd just follow the traces, but I can't see them. D:

the relay contacts probably went bad. contact resistance goes up, more heat goes into the relay body making it worse and so on.

 

[weadjust]

Is this the part. Looks like it's around $100.00

http://www.repairclinic.com/PartDetail/Oven-Control-Board/316557118/1794486?modelNumber=790.96020400

 

[phucheneh]

Yep, that's the one. I had a different number, which only pulls up $75+ refurbs. But then I found the above, which supercedes it. Better design, perhaps?

http://www.prosupplyco.com/316557118-clocktimer.aspx

That place has it for stupid cheap, but they look kinda sketchy. It's around for $65-70 bucks, though. Surprisingly cheap considering that's two boards with all the buttons, LED's, the clock/timer, that little transformer, relay, all those diodes and resistors.

Praise China.

Potted: That makes sense. It looks like the almost-a-fire was centered around the relay. Ironic that that was the part I identified as 'working.'

It was less 'why won't my heating elements switch on' and more 'how the hell did any of this manage to work at all?' Heh. I bet I could solder in some wires and fix the broken PCB traces...

...but I think I'll just pay the 70 bucks.

 

[phucheneh]

I couldn't resist.

Well, it's not...that...bad...

Gather supplies...brute force butane iron and old-ass toxic (aka 'good') solder.

Well...that's fucking ugly.

BUT GUESS WHO'S EATIN' FOOD TONIGHT, BITCHES?!?!

 

[CallMeJoe]

Copper foil tape can be cut to width/length to bridge burnt circuit traces after the carbon mess is cleaned off, then soldered to the existing traces on each end. Seal the repaired area with a conformal coating and you have a serviceable repair.

 

[phucheneh]

Mmmm...the most delicious frozen potato skins you will ever have are those that taste of success.

edit: where would I obtain copper tape? Home repair store? Radioshack? Those are probably my only local options. I'm aware lead/tin is not the best bridge for burnt traces. But I was hungry.

 

[PowerEngineer]

Nice work! :thumbsup: :thumbsup:

 

[Rubycon]

I would be a little concerned at what caused the fault.
That's probably L1->N line voltage (120VAC) there so if it flashes again it's going to scorch a bit more.

 

[Chris A]

Great job!! Lol

 

[MonKENy]

BUT GUESS WHO'S EATIN' FOOD TONIGHT, BITCHES?!?!

LMAO!! Holy Shit! Good on you!!

 

[Engineer]

See...I told you that would buff right out! :awe:

BTW, OP's comments are AWESOME throughout this thread (BITCHES)! :biggrin:

 

[DAPUNISHER]

See...I told you that would buff right out! :awe:

BTW, OP's comments are AWESOME throughout this thread (BITCHES)! :biggrin:

This

I would be a little concerned at what caused the fault.

and this as well.

And clean that oven mang!

 

[notposting]

the picture name where you found the carnage is the best

 

[Red Squirrel]

I couldn't resist.

There's a pun in there somewhere. :awe:


I too would be concerned at what caused the fault though but it's contained and it's probably only an issue when actively using the stove, so it's probably a rather low risk of fire.