Morphy Richards electric blanket controller pcb fault BEPCB020

[SparkyPete]

Hi all.

My neighbour ask me if I can try and fix her electric blanket.

The blanket wiring itself *may* be faulty, but when she took it in to a local electrical shop they did some tests on the blanket and the controller and said there was a fault in the controller's wiring.

Well, I have opened up the controller and continuity tested everything I can and it all seems to be ok, however I can't claim to understand how the controller works, although the circuit is not complex.

The resistor on the board just seems to supply the power neon, which does come on. The two contact sliders look ok, the fuse is ok and there are no dry joints or burnouts on the board, so presumably one or more of the six diodes on the board has failed.

Anyone got any ideas - particularly how I can test the various diodes? Photos below.

Thanks very much.

SP

 

[SparkyPete]

Just looked at a YouTube video on diode testing and if I've done it right, then all diodes check out ok, giving a reading of around 0.6v.

Starting to suspect it's the blanket's wiring at fault, not the controller.

 

[kellys_eye]

'Any' fault in electric blankets has the potential for disastrous consequences and should really be addressed by replacement. Clearly the controller isn't faulty so the blanket itself is - this is something a competent electrical shop should have been able to diagnose.

Don't take risks. Replace it.

 

[duke37]

The local fire brigade used to check electrical blankets, I do not think any passed.

Look to see if there is a connection in the blanket, Assume the blue wire is common and see if there is a connection to the other wires. I think there should be a connection between all wires.

The soldering looks a bit blobby but mains power should force its way through a bad joint.

There are three? elements in the blanket and the diodes will be used to use only one polarity of the AC mains. Thus several heating levels can be generated.

A hot water bottle would be safer.

 

[SparkyPete]

After testing the blanket circuits, where there was resistance on one but none on the other/s, that is conclusion I have reached as well.

It has been binned.

Cheers.

SP

 

[SparkyPete]

The local fire brigade used to check electrical blankets, I do not think any passed.

Look to see if there is a connection in the blanket, Assume the blue wire is common and see if there is a connection to the other wires. I think there should be a connection between all wires.

The soldering looks a bit blobby but mains power should force its way through a bad joint.

There are three? elements in the blanket and the diodes will be used to use only one polarity of the AC mains. Thus several heating levels can be generated.

A hot water bottle would be safer.

Thanks for explaining how the circuitry works, duke37 - appreciated.