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.
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.
