On Wednesday, February 22, 2017 at 11:27:49 AM UTC-5, R2D4 wrote:
I am on my second Sunbeam electric blanket this Winter and it is doing
the same thing as the first one I had-- starts off for a couple of weeks
working correctly, then spends a week getting weaker and weaker where I
have to turn up the controller all the way and even then the heating is
uneven and weak. I was going to return this one too, but before I do, I
wanted to ask if anyone knew of a solution to repair this? Almost seems
like there is a circuit issue somewhere, maybe in the controller, but
who knows. If it were a cheap repair, I'd just keep the blanket after
the low cost repeatable fix. Thank you.

PS: I can't think that they're making that much money on these. I read
the reviews and *many* folks are having similar issues. If a solution
isn't found for the above, I'd appreciate recommendations for a brand/
model that will last. This definitely isn't like the blanket I had
while growing up 25 years ago; that one lasted for 15 years with no
issues.

Same here. My wife and I have used the dual control Sunbeams, and they do indeed get weaker over time. I'm kicking myself for not taking a resistance check of the wiring part when new and comparing to the old. The problem is that the new blanket uses a different connector than the prev gen, so swapping the controller can't be used as a diagnosis tool.

Our Sunbeams normally lasted a few seasons getting weaker each year. Adding a second comforter on top of the regular bedspread is a good way to trap heat.

This year we bought a dual control heated mattress pad instead of the blanket and I'm sure it'll suffer the same fate. I no longer put it on anything above 4 (out of 10) and never use the admittedly handy preheat feature because it also runs the blanket or pad at 10 for half an hour before dropping to the preset temp. In any case, manually preheating at 4 and dropping it to L when I get in bed is enough to take the chill out of the sheets. I'm hoping that not using the automatic preheat and adding another comforter on top will extend the life. Time will tell I guess.

When this one craps out/gets too weak I'll do a post mortem, but I suspect it uses resistance wire which changes resistance over time. If the problem is that, then there's no fixing it.