Resister replacement - have i got it right?

Thread Starter

unclebob

Joined Aug 3, 2012
33
Hi all,

I've got a charger for a multitool which has given up, I've cracked the case open and found a burn/scorch mark around a resistor, tested across the legs with a multimeter and got open connection.

Colour banding looks like Yellow, violet, gold <white> gold.

The white is an unknown - not sure if its just a gap or i cant see it properly so hoping one of you wonderful people could confirm?

I believe if its Yellow, violet, gold gold then the value is 4.7 ohms, +- 5%?
If so, what wattage should I look to replace it with? current resistor as per pic is fairly large, with blue colour to it? and one leg is connected to 230v mains uk power. The input is labelled as 100/240v 50/60Hz 15w, The output for the charger is 13v 600mA.

So should I be looking for a 4.7 Ohm +-5% 15w resistor?
 

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AlbertHall

Joined Jun 4, 2014
11,500
4.7Ω yes, but 15W no. Look for a replacement that is a similar size to the original.
I suspect that the resistor is actually a fusible resistor and so, for safety, should really be replaced with a similar type.

This also implies that the resistor is not the cause of the problem. Some other fault resulted in high input current and the resistor blew to prevent further damage.
 

Thread Starter

unclebob

Joined Aug 3, 2012
33
4.7Ω yes, but 15W no. Look for a replacement that is a similar size to the original.
I suspect that the resistor is actually a fusible resistor and so, for safety, should really be replaced with a similar type.

This also implies that the resistor is not the cause of the problem. Some other fault resulted in high input current and the resistor blew to prevent further damage.

Thanks for the info, I left it plugged in for a few weeks (forgot to switch it off and no load!) not sure if this may have caused overheat?
 

Thread Starter

unclebob

Joined Aug 3, 2012
33
Sounds like its better to source a replacement charger? any ideas on where I can get a 13v 600mA output? most/all I can find seem to be 12v? its to charge a 12v 1300mAh Li-ion battery!
 

Thread Starter

unclebob

Joined Aug 3, 2012
33
Thanks - I've emailed walteronline as they are the "go to" company for spares for the tool range (workzone!) to confirm if their charger is the replacement for the one I have, as the voltage/current match, but model numbers that it is suitable for do not!

If they say it is the replacement then I'll get that.

From what I can see, the charge control circuit is in a separate device in the bits I have, so I'm looking for a 13v 600mA adaptor only? Otherwise I can gerry-rig a 3s Li-ion charger to the + - but have no control over the charge. I suspect the base has some control over when to stop charging etc (but not yet opened that up!)
 

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Thread Starter

unclebob

Joined Aug 3, 2012
33
No joy with walteronline - product and spares are discontinued and none of their existing line will work...

May look to take the battery apart and setup a method of swapping out the 18650's in it, and charge them standalone.
 
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