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JayTeeC  
#1 Posted : Tuesday, March 11, 2014 4:54:07 PM(UTC)
JayTeeC

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Hi all - I'm troubleshooting my double wall oven (about 10 years old), with upper oven that wont heat. No other apparent problems, display is fine, no error codes, and lower oven heats properly. Display will indicate upper oven is heating, but does not actually heat. (For what its worth, this was not a result of using the self clean cycle as I've seen posted here.)

I've already pulled the unit from the wall, tested both thermal fuses (both have continuity), tested (and swapped) both temp sensors, and tested all heating elements. No problems found anywhere. Then tested the upper oven relay and got 120VAC out of the relay (to ground) during bake, and no current when off, so relay seems fine? At this point I'm stumped what to do next. Many thanks in advance for any guidance.
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denman  
#2 Posted : Wednesday, March 12, 2014 1:29:31 AM(UTC)
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JayTeeC  
#3 Posted : Wednesday, March 12, 2014 5:21:36 AM(UTC)
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Oops - RBD305PDS14. Thanks!
denman  
#4 Posted : Wednesday, March 12, 2014 9:47:43 AM(UTC)
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See the attachment for the tech sheet.

I am assuming that the unit stays in preheat and never comes ready.
I am not sure how/where you tested the upper oven relay.
Also by upper oven relay I am assuming you mean the Double line break relay.

Unfortunately the wiring diagram does not give pin out numbers for this, just shows two Red wires at the control board.
If the relay is actually closing then you should see 0 volts across it when in bake or broil.
If it does not close you will see 240 volts.

It can get a bit confusing if referencing to ground.
The common (lower R line in the wiring diagram) goes directly to L2 so should always have 120 volts on it.
The NO (normally open) contact (upper R line in the wiring diagram ) goes to the elements.
With the oven off this line should be 0 ohms.
With the oven on it should have 120 volts on it.
Now this is where it gets complicated.
But you do not know if the 120 volts is the L2 or the L1 voltage.
If the relay closes then you see the L2 voltage but if it does not close you also will see 120 volts but this is the L1 voltage because either the bake relay or the broil relay is closed. The L1 voltage then feeds through that relay, the oven element and the thermal fuse and you see it at R of the line break relay.

I hope I explained the above OK
File Attachment(s):
RBD305.pdf (505kb) downloaded 48 time(s).
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JayTeeC  
#5 Posted : Wednesday, March 12, 2014 11:02:24 AM(UTC)
JayTeeC

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Wow, this gets complicated, quickly. Steep curve, and I'm on the shallow end.

Oven shows preheat timer countdown, and will count down, then show its ready. It THINKS its heating up, but neither bake nor broil elements will get hot.

Yes, the DLB relay (i'm just learning this stuff). I found a DIY that indicated to find the one red wire that had continuity to the lower DLB, and test it for 120V to ground when in Bake mode, and no voltage when off. I thought this would test if the relay was stuck open or closed. But that test appears to be no help.

So, what test should I run next? Could you translate your explanation of L1 and L2 voltage into specific test(s) I could do? Anything else to test or inspect, either other parts of the control board, or other oven components? If not the thermal fuse, temp sensor, or elements, what else is there besides the control board that could cause this issue?

I'm stuck for a next step, and at the very least I'd like to confirm the board is bad before replacing it - they're not cheap!
THANKS
denman  
#6 Posted : Wednesday, March 12, 2014 3:16:39 PM(UTC)
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[COLOR="Blue"]Oven shows preheat timer countdown, and will count down, then show its ready. It THINKS its heating up, but neither bake nor broil elements will get hot.[/COLOR]
This points towards either an oven sensor or a control board problem.
Below is info on how to check the oven sensor, take a look at 7, 8, 20 and 21.
http://www.applianceaid.com/ele...-range-repair-topics.php

If it was just a relay not closing then the unit would never get any heat and it should stay in pre-heat.
So if the sensor is OK then I would replace the control board.

Note that if you get the control board from AppliancePartsPros and it does not fix the problem then you could send it back. See their return policy.

[COLOR="Blue"]
So, what test should I run next?[/COLOR]
I would check the oven sensor.

[COLOR="Blue"]Could you translate your explanation of L1 and L2 voltage into specific test(s) I could do?[/COLOR]
With the oven showing it is ready I do not believe you have to follow this diagnostic path.
FYI, just i just in case you do not know how the 240 works.
Your house voltage is actually two 120 volt supplies (L1 and L2) that share a common Neutral. They are 180 degrees out of phase so when one is at positive 120 volts, the other is at negative 120 volts. therefore there is 240 volts between them (L1 to L2).

[COLOR="Blue"] Anything else to test or inspect, either other parts of the control board, or other oven components?[/COLOR]
See the start of my post.

[COLOR="Blue"]If not the thermal fuse, temp sensor, or elements, what else is there besides the control board that could cause this issue?[/COLOR]
Just the wiring between the devices is left.

[COLOR="Blue"]I'm stuck for a next step, and at the very least I'd like to confirm the board is bad before replacing it - they're not cheap![/COLOR]
If the sensor and wiring is OK then odds are very high that it is the board.
There is no good way to actually test the board as schematics are not available so it is done by the process of elimination.
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JayTeeC  
#7 Posted : Friday, March 14, 2014 7:52:02 AM(UTC)
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Unfortunately, the oven temp sensor is fine. Tested for resistance, and even swapped upper for lower... no change. So I suppose I'm shopping for a control board.. thanks Denman for your help, and let me know if you have any other thoughts. I'll post the resolution for any thread followers.
denman  
#8 Posted : Saturday, March 15, 2014 1:14:31 AM(UTC)
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You may want to give AppliancePartsPros a call.
If the board does not fix your problem you can return it.
Please see their return policy.

Most places will not let you return electronic parts.
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JayTeeC  
#9 Posted : Sunday, March 30, 2014 10:01:17 AM(UTC)
JayTeeC

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Problem solved! Replaced the upper oven DLB relay on existing board for $10, rather than replace entire board for $300-ish. :D

Longer story & recap: After testing the thermal fuses, heating elements, and temp sensor, it had to be the control board. With everything else functioning normally, and no error codes, I figured it had to be a bad relay (DLB, double line break relay) for the upper oven. Pulled the board and saw slight melting of plastic around one of the terminals on the relay (topside) and melted solder on one of the pins (underside; shown below):UserPostedImage

This usually ends in a new control board for around $300. I found a service online that will test, repair and warranty the board for $150. Great deal! Then I did a quick search on the relay itself using the part # on the relay body, and found they cost THREE DOLLARS. Add $7 for shipping. I desoldered the bad relay, and soldered in the new relay. FIXED. :)

Relay looks like this:
UserPostedImage

Underside of new relay installed (shows 4 pins to solder):
UserPostedImage

For anyone who's a bit DIY inclined, this was an easy job. Diagnose all the parts with multimeter, and if its the board and traces to relay (there could be physical evidence of excessive heat on the relay itself to make it easy to diagnose and confirm) you can DIY. Board is easy to remove, and only 4 pins to uninstall, reinstall the relay. Of course basic soldering skills required but not hard to learn.

Thanks to Denman for helping me get to the proper diagnosis, and providing great DIY instructions/diagrams/part #s.
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