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Electric Blanket Repair - Perfect Fit Controller

Discussion in 'Troubleshooting and Repair' started by CDuncan, Dec 25, 2012.

  1. CDuncan

    CDuncan

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    Dec 25, 2012
    In case someone else has a Perfect Fit blanket [not a Sunbeam product], Model LVBK-RF2 [power supply 120-18, and controller C-D7], I just repaired the controller. The controller just quit working, with the illumination LED behind the dial not coming on, nor the blanket heating up. I tried swapping the two controllers to the other blanket sides and confirmed the inop side worked with the good controller. That left the controller as the culprit.

    Upon opening up, I couldn't find any overheat or other visually suspect controller components. I saw 18vdc from the transformer into the board and output of the regulator. I tried some freeze mist on the semiconductors, and even desoldered the base lead on all the transistors to check for open and shorts [B to C & B to E, reverse and forward biased] - - no problems found. The output MOSFET [International Rectifier, IRL2703P] was suspect because its output goes directly to one of the blanket leads. I thought that static electricity could have coupled from the heating grid wires directly into the MOSFET, which is ESD sensitive - - you can hear the crackling while making up the bed with the dry winter air. I ordered the MOSFET from Mouser Electronics for only $2.25 along with some of the other cheap transistors and op amp just to have all the bases covered.

    Replacing the MOSFET fixed the problem. Hope this helps someone else with a similar problem. :D
     

    Attached Files:

  2. Valerie Lathrop

    Valerie Lathrop

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    0
    Jan 12, 2014
    Thank you profusely CDuncan for taking the time to post this solution.
    Valerie
     
  3. Doc Hallenstein

    Doc Hallenstein

    1
    0
    Dec 30, 2018
    I ordered and replaced the MOSFET as you did and still no improvement. I push the on-off button, the red light comes on for about 4 seconds and then turns off. No voltage at the blanket termination. Stumped.
     
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