Electric blanket resistor

[cliffpage]

Electric blanket, can't find name on it anywhere, think label came off years ago. Double size, some years ago one side stopped working, I found a resistor had failed in the controller. As I don't use my side of the electric blanket I turned it round so my wife could use the good side. Now the resistor has gone in that side too. Well I think it is a resistor. The mains live wire goes on one end of this component and then the other end goes to the workings of the controller. pic of the component att'd . stamped in the metal is F400H250V . I don't know what F400H means. 250V presumably means 250 volts (I am in the UK). Can anyone tell me this is a resistor for certain? from the colours it is 400 ohms with 2% tolerance, do you agree? it is ceramic with a wire through it with sand in. It does not solder in , it pushes in. I can't find any resistors like this , that don't solder in. So perhaps it's not a resistor. A fuse? but the coloured stripes don't suggest a fuse and it does not mention Amps on it. Any helpful comments please.

[eccerr0r]

Re: Electric blanket resistor

That looks like a standard 5mm x 20mm fuse size and really is a fuse, what's the specific circuit that this protects, the whole heater or just the controller? How many watt heater is it?

A 4A fuse is possible I suppose but this is unusual though not unlikely. After all, diodes and capacitors have been color bar coded in the past (along with numeric codes).

[R_J]

Re: Electric blanket resistor

It is a 400ma Fast blow fuse. Littlefuse 5x20mm series 0216

[cliffpage]

Re: Electric blanket resistor

Hi, thanks for response, I have now included a pic of inside of controller. the component fits in the holders either side of the white mains cable at bottom. quite a primitive design. one time it stopped working because the component came out of the holder at one end, which could happen just from knocking the controller about I think. I don't know much about this kind of stuff. I assumed all colour banded stuff is always a resistor. I am learning. Thanks

[cliffpage]

Re: Electric blanket resistor

pic, mains cable is at right end, the pic turned 90 degrees when i uploaded it. no idea of wattage, no labels anywhere. think label came off years ago

[eccerr0r]

Re: Electric blanket resistor

400mA indeed makes more sense for F400, but if it was powering the heater, that wouldn't, though maybe a 50W blanket isn't that useless? If it's like a 50W heater then yes 0.4A fuse is correct, especially after seeing those 1N400x diodes...

[stj]

Re: Electric blanket resistor

it's about 100w at 240v

[eccerr0r]

Re: Electric blanket resistor

you dont run fuses up to the limit...

[redwire]

Re: Electric blanket resistor

No offense but just buy a new electric blanket. They don't last forever, they get washed and moved a lot and are a major cause of fire, which led to the legislation requiring arc fault circuit breakers for bedroom circuits.
I recommend buying a new one because the pictures look like an old European design and taking the controls apart has mangled the plastic.
If the fuse is blowing there is an overload happening somewhere which is likely to be the resistance wire loop.

[eccerr0r]

Re: Electric blanket resistor

Unfortunately I'd have to agree with redwire on this. It's odd that a "dumb" blanket blew a fuse unless you knew you did something dumb to it (unsure what though...). Likely something unsafe has happened to it and the new fuse you put in will also blow shortly.

[CG2]

Re: Electric blanket resistor

I can't tell how that particular circuit works, but I took a broken controller apart a couple of years ago out of curiosity. power came in via a thermal fuse which was glued to a high value resistor wired in parallel to the main heating wire. In normal use little current passes through that resistor, but if the heater breaks, it soaks up everything, overheats and pops the thermal fuse. Bin it and buy a new one.

50-60 watts per side is common for an electric underblanket. It's surprising how hot that makes a bed when there's a duvet insulating it above. And run for an hour uses less electricity than boiling the kettle for a hot water bottle.