I have a controller for an electric throw blanket that I would like to repair, but I have no experience soldering on boards
You can see at bottom left a yellow box and a resistor. Something has burnt out in this area, and likely both will need to be replaced at a minimum
I would also need help identifying parts. The yellow box is embossed ‘Tenta’ and has printed on the side ‘TC MEX/TENTAMKP 0.1 uf 275VAC’ with some other markings obscured or damaged
Is this an achievable project?
Jesus, this isn’t a slight against you OP but as an electronics engineer I feel I need to have a rant about the shoddy design here:
First of all, I have no idea what that component is dangling off the burnt-out through-hole resistor is or why it’s there.
Surely it can’t be a part of the temperature control loop, so I would guess it’s a thermal fuse to shut off the blanket if that resistor burns because it handles power to the heating element.
If so, what THE FUCK were the designers thinking?! Couldn’t afford even a small power resistor with a heatsink and a cheap thermocouple to a temp sense IC?!
Nah it’ll be ok, either it burns out the resistor and the customer is not injured or the customer’s house burns down. Either way no deaths, just complaints about our shitty build quality.
Second, they’re using WAY too much solder for these surface mounts components.
And third, why has R16 shifted from it’s pad? Bad soldering job from too much solder? Bad placement from the PNP machine? Or, god forbid, something gets hot enough to cause the solder under that resistor to start melting?
It’s genuinely shocking the amount of stuff that’s just being allowed to be sold these days.
If you can’t get the blanket repaired OP, please consider sending this to Big Clive as he’d have a field day with this.
Am I also seeing heat shrink tubing that hasn’t been heat shrunk?
It self-shrinks when the board catches fire
Honestly this is not worth the risk, It looks like a simple enough repair a high watt resister a cap and possibly an IC (U1 looks burnt) BUT consider this, something happened to cause the failure and that something could still be around, like a short in the heating element of the throw. Whoever designed this obviously did not test the failure mode of the device. The reason things are UL rated (other certs for non US) is that they get tested and found to not fail in a manor that will cause harm to the user or fire. The failure mode of this device could cause a fire, if you repair it and the same thing happens. . . . Don’t risk it, Toss it out.
ALSO NOTE! if you do attempt it. That cap is most likely a class X2 cap and would need to be replaced with the same, don’t use just any cap!