Maker Pro
Maker Pro

Sunbeam Electric Bedspread stopped heating. Anyone know what the element resistance should be?

TomV

Feb 4, 2023
8
Joined
Feb 4, 2023
Messages
8
My Sunbeam P85KQA Queen Electric Bedspread stopped heating on both sides. I opened the connector box at the bottom of the blanket and measured the resistance of the four elements in the blanket, all four measured between 2134 & 2250 ohms. I don't know if the readings are good or not. Does anyone know what the resistance of the elements should be?

1675620841216.jpeg
 

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
If they all measure the same it's unlikely that they have all developed a fault simultaneously. Any issues, whatever they are, don't relate to the heating elements themselves.
 

Minder

Apr 24, 2015
3,479
Joined
Apr 24, 2015
Messages
3,479
Plug it in and trace the voltage, see it it ends up on the element connectors.
 

Bluejets

Oct 5, 2014
6,990
Joined
Oct 5, 2014
Messages
6,990
ohms law should give an indication.........then relate to the wattage.
#2 sums it up though.
 

ChosunOne

Jun 20, 2010
483
Joined
Jun 20, 2010
Messages
483
Can't apply Ohm's Law using the resistance of unpowered heating elements: The resistance of the heating elements increases as soon as current starts flowing and the elements heat up. Much easier to troubleshoot by tracking voltage, as Minder suggested.

But I agree with #2 summing it up.
 

Alec_t

Jul 7, 2015
3,596
Joined
Jul 7, 2015
Messages
3,596
The resistance of the heating elements increases as soon as current starts flowing and the elements heat up.
It does increase, but probably not by much, given that an electric blanket doesn't get very hot.
 

TomV

Feb 4, 2023
8
Joined
Feb 4, 2023
Messages
8
I have measures the voltage going to each of the four sections of the blanket and there is voltage present but the blanket is still not heating. I have concluded that blanket itself is defective. I noticed over 120 of the Sunbeam P85KQA controls used with this mattress on sale on eBay, which indicates that Sunbeam mattresses have a very high failure rate. If a blanket stops heating my suggestion is to just throw it away since the blankets themselves are not repairable.
 

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
and there is voltage present
What voltage? If there is voltage and resistance then there is heat. Impossible to be otherwise.

One or the other (maybe both) of your readings must be defective.
 

TomV

Feb 4, 2023
8
Joined
Feb 4, 2023
Messages
8
When temperature is set to "H" the voltage applied to the blanket elements is around 120 volts. The blanket still doesn't heat. Draw your own conclusions. I have looked unsuccessfully for information on what the resistance of the blanket elements should be but that information is no where to be found?
 

Bluejets

Oct 5, 2014
6,990
Joined
Oct 5, 2014
Messages
6,990
Can't apply Ohm's Law using the resistance of unpowered heating elements:
Utter rubbish....you can get within the ball park which is what you are trying to do.

eg...220v/2200R=0.1A = 22watts per element.(seems about right)

Or if 120v supply....(op does not really say....just that they applied 120v)
120/2200R = 54mA per element or 6.5 watts per element

Should be a wattage marking somewhere on the controller etc.
 
Last edited:

TomV

Feb 4, 2023
8
Joined
Feb 4, 2023
Messages
8
Finally located the patent document for the Sunbeam electric blanket and it did have a schematic. The explanation and schematic were hard to follow and left a lot out. I'm done fooling with the blanket.
No more Sunbeam electric blankets for me.
 
Last edited:

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
voltage applied to the blanket elements is around 120 volts. The blanket still doesn't heat.
220v/2200R=0.1A = 22watts per element.(seems about right)
22 watts (or 11W if you are using 120V) isn't something you're going to 'feel' using your hand given it's spread over such a larger area i.e. one quarter of the whole sheet. If the same 11W is delivered by the other elements you're looking at around 50W for the whole blanket - sounds reasonable to me. If you don't believe me then maybe you'd like to 'lie on it'
 
Top