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Power adapter for electric blanket crapped out

Biddeford electric blanket Controller - Digital TC12BO

I’m very much a newbie to circuit boards but I’d like to fix this on my own if at all possible.

I can’t find a parts sheet online or much help to know what to replace, but I see that 2 of the components have a Smokey look to them, so I’m guessing it overheated? Fuse looks good. Can anyone help me with this???

Update (04/07/2018)

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Hi @ashmlawson , the last pics, I would suggesting replacing those first.

What issues are you experiencing? no power to your electric branket?

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That is why I threw out my electric blanket, it was breaking down to much

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Same here. I was also always worried that it would catch fire

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I was freaking out that fire that’s why I got rid of it. I am still in awe how the Japanese live under those kotatsu tables hough

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Hi @ashmlawson ,

There is always a reason for components overheating. Usually it is due to excessive current flow.

Replacing the 2 resistors may not fix the problem of why they both overheated in the first place.

Without a circuit diagram it might be difficult to find the real cause of the problem.

I suggest that you use an Ohmmeter to measure the resistance of the "coil" circuits in the blanket. Looking at the top picture there appears to be a 4 wire cable leading away from the board which I assume goes to the blanket.

To me this indicates at least 3 circuits in the blanket with a return path. (I may be wrong with all this of course). You may have to disconnect the wires off the board (mark the wires as to what wire goes where before you do so that you know how to reconnect them) and then measure the circuit. One may be significantly lower in resistance (even s/c perhaps) than the others and this is perhaps why there is more current flow than normal, overheating the 2 resistors on the board.

This is all supposition on my part and the fault may well be in the circuit board, but you have to start somewhere.

If there appears to be no problems with the blanket circuit then you'll have to trace the paths from the resistors to see what other components they initially connect to and check them for possible faults.

As I said earlier without a schematic not the easiest thing to do.

Good luck!

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they are both 10 ohm fuses and thats the weak spot in every one of those Biddeford controllers. I have 3 of them with those resistors smoked. there small resistors if you jump them the unit will turn on and error out, But that will atleast prove to that the resistors are indeed the problem.

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The 3 elements array is a thermal fuse + resistor protection circuit.

Thermal fuses opens at specific temperature value (normally 100gC)

When resistors overheats produces thermal fuse opening and circuit protection.

You can try replace those 3 elements and check normal operation.

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Yes it worked great.

we have 4 of these blankets and all have now had those resistors in the thermal aray smoke. All have been replaced and used long enough that its safe to say there wasnt any shorts in any of the blankets.

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