What normally goes bad on an electric blanket controller?

Discussion in 'General Electronics Chat' started by designer85, Jan 27, 2016.

  1. designer85

    Thread Starter New Member

    Jan 27, 2016
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    I've got a Sealy (beddeford) queen sized electric blanket that comes with 2 controllers. Model TC1583. They are the digital ones that go from 1-9 and both will not turn on. They've been working fine since we got them about 5-6 years ago. When we no longer need the blanket we put it away, but the controllers have stayed plugged in, but turned off this whole time. This year they will not turn on at all. I'm a bit of a newbie, but I'm fairly familiar to the inside of electronics.

    I'd just like to know what is the most common thing to fail in something like this so I'll know what to check. Everything looks ok from a visual check. I've got a multimeter, but I'm not exactly sure what to check and what will tell me if something is good or bad. Any help is appreciated. I'm attaching what the controller looks like below from an image I found online.

    [​IMG]
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Welcome to AAC!
    Is the control intended to 'remember' its last setting? If so, there may be an internal battery which has died.
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    If left plugged in an outlet for half the year, then I would suspect power surge damage on the input side of the circuit.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Disconnect them from power for a while (10 seconds or more) and plug them into a known-good wall socket. Make sure they are also connected to the blanket. Check for a battery as noted.

    This will rule out the obvious stuff that you need to do before thinking about opening one up. Are they independently powered, or one from the other? It would be odd for both to fail. There could be an internal fuse that has blown and taken them both out.
     
  5. designer85

    Thread Starter New Member

    Jan 27, 2016
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    Thanks for the welcome! I honestly can't remember, but I don't see a battery. I'll post a photo of the inside in a minute.
     
  6. designer85

    Thread Starter New Member

    Jan 27, 2016
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    They are independently powered. They are two identical units and each has its own power cord. I do see a fuse on the board, but they both look ok.
     
  7. designer85

    Thread Starter New Member

    Jan 27, 2016
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    [​IMG] [​IMG]

    Here is the front and back of one of the controls. The fuse is intact on both.
     
  8. SLK001

    Well-Known Member

    Nov 29, 2011
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    Make sure that you are plugged in all the way to the blanket part? Check to see if there is DC voltage on C3.
     
  9. designer85

    Thread Starter New Member

    Jan 27, 2016
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    I'm getting 2.64v on C3. The controller would normally work without being plugged into the blanket. As long as it was plugged into the outlet it would turn on and you could adjust the settings. Now it's like its completely dead.
     
  10. wayneh

    Expert

    Sep 9, 2010
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    Check for continuity across the fuse, just to be sure. It's easy to miss the break sometimes. Then check the big white thermal fuse labeled THF on the board.
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    It may be a trick of the light, but is the top of that big C2 cap bulging?
     
  12. SLK001

    Well-Known Member

    Nov 29, 2011
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    No. It's the light. The light is coming from the top. The "pre-stessing" indents are still down and mostly straight across, as seen by looking at the reflected light.
     
  13. wayneh

    Expert

    Sep 9, 2010
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    If you want a quick fix attempt, just replace all the electrolytic caps. It won't cost much, and there's a distinct possibility you have bad caps. They don't need to burst to go bad. They "dry out" with age.
     
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