"Tips", from my shop work #1: TIP, using a LiL, Basic electronics to repair power tools

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Blog entry by hobby1 posted 12-21-2013 01:50 AM 1360 reads 0 times favorited 2 comments Add to Favorites Watch
no previous part Part 1 of "Tips", from my shop work series Part 2: upgraded charger wow, »

Hi guys,
Basic, electronics is another one of my hobbies for the past 30 some years, that allows me to be able to trouble shoot a lot of my power tools, when they act up.

Here is a quick tip, for those battery tools that won’t charge up, first thing that comes to mind is probably a bad battery, or the charger is bad, in my case my B&D battery drill wouldn’t charge up, when I went to wrap up the charger cord to take it home with me, from my job, I noticed that the polarity plug that goes into the drill from the charger had a broken wire, so that explains why it wouldn’t charge the battery.

So I got it home and stripped the wires at the polarity plug, and temporarily connect jumpers to these wires back to the charger, and plugged the charger in to check for voltage output.
My meters showed no voltage out.

So the next procedure was to check to see if the circuit board is functioning properly, so I had to cut open the case and take out the little diode bridge circuit board, I put my volt meter on the secondary side of the transformer, to check for any AC output voltage, zero output, so I know that I can skip checking for any bad diodes, and go directly to the transformer itself, I put my meter on the secondary windings to check for resistance continuity, it showed continuity, so then I put my meter on the primary windings and there was no continuity, the primary windings has a break in it, so a quick check through my junk box of electronic components, and I found a radio shack 1.2A power xformer, the original B&D charger was using a 250mA. xformer, so my xformer is overly adequate, after replacing the xformer the battery drill charges fast and strong.

So the moral to this blog is, check all the major components when trouble shooting your power tools, because in my case, the wire broken wasn’t the only culprit in a bad charger, it was the xformer itself, that made the charger not to work properly.

Had I not known to check further and what to check as well as what to expect in measurements, I would have thought it was a bad battery, but by investigating the whole charger from top to bottom, allowed me to keep the drill and its perfect working battery, without having to buy a new kit, because I really did not want to have to get rid of this drill because of a misinterpretation of a supposedly,bad battery.

An additional, note, it appears that I have upgraded my charger, my drill was totally dead, no power at all, but now within 5 to 10 min. my drill is fully charged, and very very strpong torque to it, like I never had before when it was new, this drill charges fast and strong, this is definately an upgraded charger for this drill.

2 comments so far

View stefang's profile


15881 posts in 3333 days

#1 posted 12-21-2013 09:31 AM

It sounds like you have a lot of very useful skills Hobby1. I went through a couple battery powered drills before I bought my deWalt with three battery packs. I really love it. It would be hopeless for me to trouble shoot and actually fix anything electrical more complicated the rewiring a plug.

-- Mike, an American living in Norway.

View hobby1's profile


335 posts in 2297 days

#2 posted 12-21-2013 04:42 PM

Hi, Mike,
I’m glad your having good success with your Dewalt battery drill , after the frustrations of those other drills not working properly.

The Dewalt chargers are probably really good, to charge there batteries to maximum usage.
and 3 batteries, that is very generous of them to put that in there kit.

The only battery drill I got that came with an extra battery, was my metabo powermax drill kit, I like it for drilling pilot holes using finish nails, it came with 2 batteries total.

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