Saturday, February 18, 2012

Magic Chef Gas Stove Repair

Our house, that we've been in for about twelve years now, came with a Magic Chef gas stove, Model No. 3468XVA. It's quite a decent stove, but it's not maintenance free -- I've had to replace oven ignitors a couple of times. We recently had an incident where an ignitor failure took the control panel with it. That can make for a costly repair, and we briefly considered replacing the stove with a new one.

Then, I thought long and hard about the cost of that, and the difficulty of getting the old stove out and a new one shoehorned in, and the outrageous waste of tossing what is mostly a perfectly good stove and concluded that a repair job was in order.

Fortuitously, it turned out that my son has an acquaintance in the appliance repair business. His acquaintance kindly offered us repair of the control panel, and non-OEM replacement ignitors for a lot less money than I'd expected to pay. I went for that like a cat goes for tuna. I just received all the parts yesterday, after a couple of weeks' wait for the control panel repair.

So, it's stove repair time at our house today. I sure hope this goes smoothly. Permit me here to give you some information about gas oven ignitors of this oven's type.

Ignitors

['Ignitor' can also be spelt 'igniter', for what that's worth.]

The oven has two ignitors -- a broil ignitor for the upper burner, and a bake ignitor for the lower burner. Here's a view of an old one.

The Owner's Guide calls it a 'glo bar'. What it amounts to is a big, open-air electric light bulb filament. To light a burner, the ignitor is first energized until its 'filament' glows white-hot. The electronic controller then opens the gas valve, the gas encounters the white-hot 'filament' and ignites.

Ignitor failure appears to be the commonest problem with these stoves. I've seen it express itself two ways.

Typically, oven (bake) operation becomes erratic -- the oven won't maintain a set temperature. Replace the bake ignitor and you're back in business.

The other symptom an ignitor can bring on is that it trips the stove circuit's breaker in the house's breaker panel. When that happens, do not reset the breaker and try again. Abandon use of the oven until the ignitor is replaced. Resetting the breaker and trying again is what led to control panel failure in our stove; more on that later. (By all means do reset the breaker, though. The stove-top burners' ignition system is still useable. Just don't retry lighting the oven.)

Replacement Ignitors

OEM (Maytag) replacements are outrageously costly. The appliance parts outfit near where I work quoted me $99.00 for one, and I wanted to replace both while I was at it.

It turns out there's an outfit name of Supco that makes replacements for all manner of OEM parts. Here's a view of Supco's replacement for a Maytag P/N 12400035 ignitor.

It comes with two styles of connector shell bits and their mates, in case the mating connector in the stove is a ruin (unlikely, actually). There's also a wad of thermal insulation material, and a mounting plate of some sort for replacing a slightly different style of ignitor.

So far, so good. I sure hope I don't end up regretting that I didn't go for OEM parts.

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Replacing the Ignitors

Bake Ignitor

To get at the bake ignitor, first remove the racks. There's a porcelainized steel panel at the bottom that has to come out. Unlatch it at the rear, tip up the rear end of it and you can free its front lip and remove it.

Here's a view of the bake ignitor at the bottom rear of the oven.

It's held in place by two screws. The broil ignitor up above is similarly mounted, though its fasteners are a bit more awkward to get at because of the broiler's heat reflector.

The bake ignitor is replaced from inside the oven -- there's no need to remove the back cover of the stove. Remove the two screws with a 5/16" nutdriver. (The screws are 10-24 x 5/16" hex head.) Tug on the wiring and coax the connector out past the burner tube -- it can be a little obstinate, but it does have clearance to come out. (You'll likely disturb some insulation material.) The wiring has enough slack that the connector can be got hold of and disconnected. Connect the new ignitor, stuff the wiring back down the hole, stuff in the insulation material provided and fasten the ignitor in place.

Broil Ignitor

It might be possible to replace the broil ignitor from inside the oven as well, but removing the stove's rear cover gets you certain, easy access to the ignitor's connector. (I long ago installed low-profile appliance rollers on this stove, and I'm ever so glad I did; it makes this sort of job a lot easier.) You need a No. 2 Phillips screwdriver to remove six No. 8 x 1/2" truss head screws. With the rear cover off, disconnect the ignitor and then go to work on the ignitor's fasteners inside the oven. They're not at all pleasant to deal with because of the heat reflector in the way. You may want to have a 1/4" square drive universal joint arrangement, and a 5/16" box end wrench in addition to a nutdriver.

There's a small baffle-plate that has to come off (one screw) to permit the connector to come through from the back. Feed the new ignitor's wiring through its hole, fasten the ignitor and reinstall the baffle-plate. At the back, stuff in the insulation material provided, connect the ignitor and reattach the rear cover. That's it for ignitor replacement.

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Control Panel

It turns out that I'll have to wait awhile longer to install the control panel. Someone's quality control went AWOL, and my repaired control panel is missing some pieces. That's being attended to. Meanwhile, I can at least show and tell what happened to the original control panel.

Until this incident, the stove's control panel has been trouble-free. Here's a view of the front of it.

And here's a view of the back of it.

Those two black rectangles are the ignitor relays.

Earlier, I warned against making retries when an attempt to light the oven trips a circuit breaker. Here's why I made that warning.

Conductive printed circuit foil runs associated with the bake ignitor's relay ended up acting as 'fuses', and partially vapourized. It looks as though attendant arcing may have taken out an integrated circuit (IC) on the opposite circuit board. Needless to say, it's game over for that control panel.

When I get the missing pieces of the 'repaired' control panel, I'll show what that was all about, and finish up this repair and post. You'll see that control panel replacement is a straightforward job -- not at all difficult or daunting.

SATURDAY, MARCH 3, 2012

Control Panel Replacement

The control panel ended up back at the repair outfit for confirmation/correction of its defect, and yesterday I got it back complete and ready to go, presumably.

What had happened was that eight little rods associated with the panel's push-button switches had been left out; the panel was completely inoperable. How it managed to get out the door of the repair place like that is beyond me. Anyway, it's now complete and it has a warranty seal on it, so it looks like they may have been paying attention this time.

Control panel replacement can be done entirely from the front of the stove, there's no need to get at the back of it except to UNPLUG IT BEFORE PROCEEDING -- line voltage is present at several of the control panel's terminals.

The stove's console face is fastened in place by four screws, two at each end. You'll need a stubby No. 2 Phillips for the two lower screws. With the screws out, the console face can come away and be laid down like so.

There's not a lot to the wiring. At this point, draw a sketch of the wiring or label all the wires. Disconnect everything.

Two screws fasten the lower lip of the panel's sheet metal surround to the console face. With those removed, you can get to here.

Four screws and the panel comes out -- not a difficult job at all.

The only bit of difficulty I ran into was in getting the screws that fasten the console face back into place -- the construction of the console ends is atrocious.

Anyway, everything appears to be working. The glowing ignitors don't photograph well, but here's a view of the broil ignitor just before the gas valve has opened.

Hot stuff.

And here's the broiler lit.

Provided those non-OEM ignitors prove reliable, this will have been a very low cost repair. This evening, the bake ignitor will get a workout. We'll see how that goes.

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Update -- SUNDAY, MARCH 25, 2012

The repaired control panel lasted about a week, then it up and died. I was a little leery of it right from when I installed it because the display seemed not as crisp as on the old one, and its beep tone was odd -- harsher.

Anyway, I got it back today, repaired under warranty. It's back in the stove and its display looks good, so maybe that's an end to the aggravation for awhile.

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