Hitachi 18v battery charger

[clogsParticipant @clogs]

I have a 5 year old Hitachi 18v drill driver (UC18YRL, NI-MH, NI-Cd), not done a lot of work really……the drill head works off a 12v car battery…….

had a look inside the charger after hearing a click….!!!!!

seems that a little something has burnt out…it says on the board R8…..has two fine wires soldered to the board and is about 1.5mm in diameter and 4mm long…….seems a shame to throw the drill away for just this and a genuine charger is £55…..a third of the price of a new machine..

must be poss to solder a new part in just to try….?….

does the R8 mean something and where can u buy a new 1….?…….

many thanks clogs

[clogsParticipant @clogs]

[JasonBModerator @jasonb]

Probably means resistor number 8, unless you can read the colour bands around the outside it will be hard to tell what size it should be.

[clogsParticipant @clogs]

sorry, real burnt can't see any colours at all……clogs

[not done it yetParticipant @notdoneityet]

It is likely that something else has gone short cicuit to fry the resistor. It is fairly low power, 100mW or less, I would think, so likely quite a high resistance.

Are there two similar circuits on the board – perhaps a mirror image – so the value can be found on a good one?

I would guess it is associated with a transistor which has gone phut! Replacing just the resistor will likely not resolve the underlying problem.

[Grizzly bearParticipant @grizzlybear]

Hi clogs,

I was tasked with a similar charger, saw the burnt resistor, long story, short, gave it back to the owner. He rang me about a week later, he had fixed it with a new resistor. he had found the info. on the 'net. I don't know the resistor value. I will look on the 'net.

Regards, bear..

[Grizzly bearParticipant @grizzlybear]

Is this any help?

http://www.eevblog.com/forum/reviews/hitachi-lithium-battery-charger-question/

bear..

[I.M. OUTAHEREParticipant @i-m-outahere]

Without the schematic and a basic understanding of electronics you are really up against it !

I had a workmate who asked me to take a look at the charger for his dewalt drill as it had gone pop for some unexplained reason but as it turned out it was a fairly common occurance with these chargers.

After opening the case up and replacing the fuse the unit came to life but wouldn't charge so out came the circuit board, on the back side of the board there were many surface mount components including the controller chip but there were a couple of components that had vapourized i then decided it was going to be more trouble than what its worth to continue so it was handed back to the owner . He could buy a genuine charger for $60 au for a basic unit or $30 or so for a chinese knock off , he ended up buying a new drill of the same make and the batteries of the old drill are the same as the new ones so he can charge them in the new charger .

Have a look on ebay sometimes you can pick up a used charger cheap .

[David George 1Participant @davidgeorge1]

A friend bought a second hand rechargeable Ni Cd drill which the batteries were us and no charger, he bought a set of Ni Ch batteries and replaced the the us batteries charged said batteries and it worked. Later he was doing a test to see how long they would last when it got very hot, exploded, and was like a bomb. He found out later that you have to monitor the batteries with a small circuit board and not overcharge or over discharge.

David

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