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  1. #1
    Join Date
    Nov 2006
    Location
    Wisconsin
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    Southbend GS Oven

    I'm working on a Southbend oven. Model: GS/15SC Serial:16E40781. This oven is stacked above an older southbend, flues tied together. The lower oven has no issues, and performs flawlessly. The ovens share a gas supply, and are on separate outlets.

    The problem I have is the top oven will light, drop out the flame, and do this three times till it locks out on ignition failure. Originally, I cleaned the flame sensor and polished the burner by it. This originally had the fenwall ignition control, so I checked microamps at the board. It showed 3 microamps, but still locked out.

    I ordered a board and replaced it. New board does the same thing. Now I dive a little deeper. I pulled apart and re connected all molex plugs. Confirmed incoming power is wired correctly, and transformer is wired correctly. Ignition board gets constant 27 volts through the ignition trials. Gas valve outlet is steady at 4" wc as per name plate. The blue Replacement board doesn't have pins to check flame sense, so I hooked my meter in series with the flame sensor. 0 micro amps when it lights.

    Boss says order flame sensor. I order flame sensor, still same issue. I did measure ohms from where the flame sensor plugs in, to where the sense wire pin on the ignition board is, as it goes through a few other connectors, 0 ohms. I also ran a jumper wire from the burner frame to the ignition board ground, no change.

    I did check the convection fan. It is running in the right direction, and stays on the whole time. Flues are still attached and seem fine. I really thought this was a flame sense issue.
    But after really watching this, with a nanometer, and meter on the gas valve pins, it seems the flames light, swirl around, and almost snuff out. Then the control drops out. From what I see the wheel didn't have any plastic or big chunks in it, flues seem fine.

    Any ideas? Most of the time I just change ignitors or motors on these. Thanks

  2. #2
    Join Date
    Jan 2016
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    The triangle in the Keystone
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    Near the end of your post you say the “flames light, swirl around, and almost snuff out. Then the control drops out”

    Sounds like the gas is dropping out before flame is proved and then the control drops out. You have 4” at the valve outlet though. I wonder if there’s a burner or orifice issue?

    I had an Imperial do something like this a couple months ago. Several techs went out and replaced everything in the flame circuit only to still have the original flame rectification issue present. I noticed my microamps would start high but after a few seconds it would drop dramatically. The burner had a bunch of hairline cracks by the stamped out holes that caused the flame to waver and wander. New burner, no more issues.

    Or I wonder if you have a hole in your combustion chamber somewhere and the convection blower is blowing air into the burner area.

    Or a bad brand new module.


    Sent from my iPhone using Tapatalk

  3. #3
    Join Date
    Oct 2010
    Posts
    96
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    Make sure the plugins connector strips for the Fenwall module have a solid contact. I hate this Southbend model. This seems like a common problem with these. I'm not sure what you mean with the flame swirling around? I once had a tech install a new motor on a Southbend but placed the mounting plate back on the oven in a different position. Normally this wouldn't matter but it did with this Southbend oven.

  4. #4
    Join Date
    Oct 2012
    Location
    riverside calif
    Posts
    513
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    You mentioned different outlets, have you verified you have a good ground on the troublesome unit.
    Sent from the van with the a/c on.

  5. #5
    Join Date
    Nov 2006
    Location
    Wisconsin
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    Thread Starter
    Found the problem after talking with tech support. There are two solenoid actuated damper plates that are used to save heat when the burner isn't running.

    The linkage rods had broke off the damper plates. This caused an incorrect air/fuel mixture, as explained to me by tech support.

  6. Likes The Turtleman liked this post
  7. #6
    Join Date
    Jan 2016
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    The triangle in the Keystone
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    Well how about that! I can’t remember seeing a damper system in this model before, even on newer ones. I wonder if it’s an option.

    Well I’m glad you solved the problem.


    Sent from my iPhone using Tapatalk

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