Oven displaying wrong temp...

Hi,

I have a Maytag Gemini stove model # MER6872BAW, about two weeks ago everyone started noticing that nothing was getting fully cooked in the upper oven. We use the upper oven a lot so I figured it was either the sensor or the element.

I stuck a fireplace thermometer in the upper oven just to make sure everyone wasn't going crazy, the temp on the oven's digital display said

400 degrees, the fireplace thermometer said 310. I stuck the thermometer in the lower oven, the display and the thermometer both said 400 degrees.

Figuring that it was the sensor I replaced it, the upper oven still acted the same. I was able to find a schematic for the oven on Sears.com, the sensor goes straight back to a connector on the circuit board inside the control panel.

The new and old sensors both read a little over 1000 ohms, the sensor connectors for both lower and upper ovens are both reading 5.15 volts DC. My only guess on this is that there is something wrong with the circuit board. I looked it over all the parts look fine, no burnt resistors, none of the capacitors are bulged at the top, no popped transistors.

The oven did give me a code F9-3 while I was working on it which decodes to: "Check for obstruction in door lock mechanism" (there is nothing in the mechanism). Oddly enough six months after we had this stove it gave that code with no warning at all, it gave another code too but I do not remember that is was. A month later it did it again, then no problems with it at all for three years until too weeks ago.

Anyone have any suggestions on what might be wrong?

Reply to
lj_robins
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Well I don't know much about that stove, but I do have some experience with transducers (sensors). There's probably nothing wrong with the transducer itself. The transducer would have to run onto the stoves circuit board and into an a/d (analog-to-digital) converter and the resulting hex value would have to be read by a microprocessor. The hex value is meaningless to the processor by itself so it needs something to reference it to to give you the resulting temperature (this is all assuming the stove displays the temperature on a digital display). What I'm getting at is ........bad calibration/incorrect programming on the part of the manufacturer. Now don't take my word as gold but you might want to look into that possibility.

Reply to
tconnors23

Can you exchange the sensors, or exchange the connections, to localize the fasult to sensor or not-sensor?

Bill

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Reply to
Bill Jeffrey

Control on our oven can be calibrated/offset. Could it have been changed? Just brining it up because you don't mention it.

Reply to
T Shadow

I doubt that code has anything to do with the problem.

Does the control board have any analog conditioning after the temperature probe? If so are there two identical circuits? If you can compare readings right at the pin into the microcontroller you'd know if the problem was before that or within it. You might simply have a bad ADC in the microcontroller in which case you're pretty much SOL unless you feel like writing your own code from scratch to program a replacement.

Reply to
James Sweet

Thank you for all the replies, it turned out to be a bad solder joint on the controller board, oven works fine now.

-Landon

Reply to
lj_robins

Damn! the old bad solder joints, they'll get you every time!

Reply to
t- 4 technician

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