Troubleshooting Electric Blanket

[DanFen]

Re: Troubleshooting Electric Blanket

Are you referring to these two?

There are two switch contacts, one on the line side one on the neutral side, They both need to be making contact, There must be a plastic actuator that presses them so they make contact. I would be carefull there will be 240vac across them.

[R_J]

Re: Troubleshooting Electric Blanket

There are two switch contacts, one on the line side one on the neutral side, They both need to be making contact, There must be a plastic actuator that presses them so they make contact. I would be carefull there will be 240vac across them.

I also just notice a smd resistor that seems to be missing, It is R2, it is part of a series of 4 resistors

[DanFen]

Re: Troubleshooting Electric Blanket

Mind explaining in baby terminology, what you're referring to when saying "element"?

EDIT: At this stage I am not even connecting the actual blanket, the controller should light an LED if it's functioning (I also know cause I have a very similar one that works, LED lights on even with the blanket disconnected).

check resistance of the element ... i guess it will be about same as a 60w to 100w light bulb .

[petehall347]

Re: Troubleshooting Electric Blanket

check resistance of the element ... i guess it will be about same as a 60w to 100w light bulb .

[DanFen]

Re: Troubleshooting Electric Blanket

OK, now I have 220V on the connections (on the circuit). So, this confirms that my readings were wrong.

So F1 is the white one in between of the resistors right? If so, then yes it's good.

F1 is a thermal fuse

[R_J]

Re: Troubleshooting Electric Blanket

F1 is a thermal fuse. If should check like a short, if it does not, then it is open circuit. It can be jumped with a piece of wire ONLY TO TEST. then it MUST be replaced with a thermal fuse.

[DanFen]

Re: Troubleshooting Electric Blanket

OK, in that case, my reading might be wrong then. I'll attach again to the board and try again.

F2 is fine (checked in continuity mode of course). F1... isn't that a resistor?

The ac cord must be ok and your reading when connected to the board must be wrong. Did you check the fuses on the board?

[R_J]

Re: Troubleshooting Electric Blanket

The ac cord must be ok and your reading when connected to the board must be wrong. Did you check the fuses on the board?

[DanFen]

Re: Troubleshooting Electric Blanket

Good question as I said, I'm a newbie. If you say it's impossible then something tells me I'm measuring something wrong. Not sure what to tell you really

In the meantime, we have light. So this tells us that the wiring is fine right? I can solder the wiring back onto the board and measure voltage on the contacts again, unless there's anything else you'd suggest we test.

Do you really think that little board is loading down the 240 volts coming out of the outlet?
Connect a light bulb to those wires and see if it lights up.

[R_J]

Re: Troubleshooting Electric Blanket

So this is the voltage measurement of the cord (i.e. from plug to meter).

I'll check the resistance. So I just have to remove the wiring from the plug itself and check each wire from one end to the other (for resistance), right?

Do you really think that little board is loading down the 240 volts coming out of the outlet?
Connect a light bulb to those wires and see if it lights up.

[DanFen]

Re: Troubleshooting Electric Blanket

So this is the voltage measurement of the cord (i.e. from plug to meter).

I'll check the resistance. So I just have to remove the wiring from the plug itself and check each wire from one end to the other (for resistance), right?

EDIT: Resistance is 0 on both wires (I've zero'ed them out before measuring).

[R_J]

Re: Troubleshooting Electric Blanket

The cord is broken, the wire is not connecting between the a/c outlet and the board. Check the resitance of both wires in the cord.

[DanFen]

Re: Troubleshooting Electric Blanket

Can you please explain what "open" means? Not familiar with the term. Can't understand how it's possible to measure ~217VAC directly and then ~2VAC on when in circuit. I can't be that bad to be measuring wrong (or am I?)

Your ac cord is open. There is no way the board is loading down 240vac! If it was your mains breaker would have blown.

[R_J]

Re: Troubleshooting Electric Blanket

Your ac cord is open. There is no way the board is loading down 240vac! If it was your mains breaker would have blown.

[DanFen]

Re: Troubleshooting Electric Blanket

Double checked. Ive' removed the connections out of the board and voltage is ~217VAC.

As soon as I solder the connections to the board again, and measure the VAC of the same connections as highlighted in my first photo, it measures 2VAC only.

[DanFen]

Re: Troubleshooting Electric Blanket

No, when I measure the voltage while connected to the board, it measures 2VAC, when I measure them outside of the circuit, they measure ~240VAC.

I will remove them again, cause I did this a week ago, and now I'm in doubt

F2 is OK. Is F1 a fuse or a resistor?

So your measurment in post #1 was wrong? and you do have 240vac across the two points with the arrows? If that is the case, check both fuses F1 and F2 (white) on the board. If they are ok, check the resitance across the two wires going to the blanket, it could be the blanket element is open.

[DanFen]

Re: Troubleshooting Electric Blanket

Yeah noticed that too, on both sides actually :/

Gotta love how the live wires (240V) have been crushed, by the screws that hold the case together.

[Harvey]

Re: Troubleshooting Electric Blanket

Gotta love how the live wires (240V) have been crushed, by the screws that hold the case together.

[R_J]

Re: Troubleshooting Electric Blanket

Sorry forgot to mention that I already desoldered the connections and tested the voltage directly, and it measured ~240.

Thanks for the explanation about the AC. Am I right to say that the SCRs are the two black components next to the caps?

So your measurment in post #1 was wrong? and you do have 240vac across the two points with the arrows? If that is the case, check both fuses F1 and F2 (white) on the board. If they are ok, Check the voltage across C1 & C4. also check the resitance across the two wires going to the blanket, it could be the blanket element is open.

[DanFen]

Re: Troubleshooting Electric Blanket

This is the other side. "There's plenty of stuff going on on the other side of the board" was a little bit exaggerated

EDIT: Pads on the top control the timer, pads on the bottom control the temperature.

unclip that board and see what's on the other side - and check the power cable for continuity.