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GE Range JGB770SEF1SS Convection heats but don't hear fan, doesn't hold temperature

helpathome

Premium Member
Joined
Jan 5, 2021
Messages
5
Location
menlo park, ca
Model Number
JGB770SEF1SS
Brand
GE
Age
6-10 years
GE Range (Model JGB770SEF1SS I think -- looks like JGB770SFF1SS to me on the range but I can't find that number online, and JGB770SEF1SS looks like mine).

Purchased in 2014-15, have never used the "convection" setting before.

Turn on convection and oven gets hot and appears to preheat -- but does not reach desired temperature.

I don't think I hear the fan operating.

When I then switch to conventional bake, it is much cooler than what I had set it for on convection setting. For example: set convection bake at 350, it preheats and rings when it thinks it is at 350, then I stop convection and go to conventional bake at 350 and it says the oven is about 260 as it preheats. Independent thermometer inside oven confirms it's not at 350.

Called GE and they will send someone out for $150 plus whatever parts/labor is -- the whole stove is probably worth <$1000 so that makes no sense.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
117,052
Location
McMullen Valley, Arizona
Hi,

Yes, you can test the voltage, with a multimeter, at the convection fan motor for 120 volts. Pull the range out from the wall, then unplug it, then remove the back access panel, then you should see it. Then remove the wires from it and put your meter probes in each wire, then plug the range in and set the control oven control settings, as you normally would on the control panel for convection bake at 350.

Then unplug your range after your done testing the motor and put the wires back on the motor and put the back access panel back in place, then you can plug it in again.

Here's the convection fan motor for your model you can order here if needed:
Convection Fan Motor


Jake
 

helpathome

Premium Member
Joined
Jan 5, 2021
Messages
5
Location
menlo park, ca
Thank you very much, Jake, I appreciate your reply. I think the motor is OK, and there is an issue with power getting to the motor.
Here's what I've done so far:

--As you described, I checked each of the three wires while the oven was plugged in, then I turned on convection 350. While it was warming up, none of the wires had any voltage. So, Blue-Red, Blue-White, Red-White --- all had 0.0 Volts when plugged in and turned on and set to convection bake 350
--I checked the motor -- all 3 pins have resistance (that I think is appropriate) -- two sets of pins have about 25 ohms, one set has about 12 ohms.
--I wiggled the door closing latch to make sure that the oven recognizes the door is closed -- that seems to work fine. When i manually push in the pin (top right corner of the range), I hear a 'click' that makes me think the oven recognizes it is a closed door. The voltage didn't change on convection bake 350.

Do you think I've checked it correctly? If it's not the motor, but the power to the motor, do you have suggestions?

Thank you
David
 

helpathome

Premium Member
Joined
Jan 5, 2021
Messages
5
Location
menlo park, ca
Update:
I measured again, this time setting the convection bake to 200 degrees to test the voltage once it reached the desired temperature.
I do get 120V when I measure the red and white wires -- it changes from 0 to 120V when the display reads 200 degrees.
I still get zero volts when I measure red and blue and also zero when I measure white and blue.

I don't understand why there are 3 wires (doesnt appear that one is the ground -- they all connect to the motor).

Can you advise me if you think a new motor is still what I need?
Thanks
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
117,052
Location
McMullen Valley, Arizona
I don't have the wiring diagram for this model, so I have no clue what voltage those colored wires you mentioned above should read.

All I wanted you to do is simply take a voltage reading at the 2 wires that connect to the convection fan motor and see if you get 120 volts when you start the convection cycle.

Jake
 

helpathome

Premium Member
Joined
Jan 5, 2021
Messages
5
Location
menlo park, ca
Got it: there are actually 3 wires attached to the convection fan motor -- two of them (red, white) have 120 V once the temperature gets to the set level. The other one (blue) doesnt have power (zero volts).
I don't know why there are 3 wires; red and blue have copper attachments and white has a silver attachment that makes me think it is ground.
Here's a picture of them attached to the motor.

I don't want to replace the motor if it's really a problem with the blue wire.
 

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Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
117,052
Location
McMullen Valley, Arizona
Ok, that is odd, and again without the wiring diagram, I have no clue where that blue wire goes. So its best to have GE come out at 1-800-432-2737 and see what's going on. They will have the wiring diagram and schematic for your model.

Jake
 

helpathome

Premium Member
Joined
Jan 5, 2021
Messages
5
Location
menlo park, ca
Thanks -- actually I'm fairly confident I figured this out--including it more for your interest rather than to try to fix it, since I think it's too complex to get to the wire that is the problem. Enclosed is the wiring diagram.

I was able to test the blue wire -- both ends. The end of blue that attaches to the motor has infinite resistance when checked to the stove's power cord. The other end that attaches to the control panel (white clip labeled "CN650" and numbered "1") has zero resistance when checked to the stove's power cord.

That tells me that there is a break somewhere in this blue cord.

The problem is that the blue cord runs deep into the guts of the stove, and I'm reluctant to take the whole thing apart to find the break.

If you think it's pretty easy to find the blue cord, maybe let me know. Otherwise, I think I'll just live without convection for now.

Thanks for helping me with this interesting problem!
 

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Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
117,052
Location
McMullen Valley, Arizona
Great thanks!

Why don't you just ohm test that blue wire from the convection motor to CN650 Pin 1?

Jake
 
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