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Frankenstein's Fix: The Dead Drill

Don Tavidash
10/25/2013 06:43 PM EDT

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David Ashton
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Re: drill saver!!!! & advice if possible
David Ashton   6/14/2014 9:53:32 PM
@Monty44 - yes I am still here!!

> "I've got a B&D 18v drill..."   Mine is 14.4 volt

> "charger (ref 486910-17)"  mine is 486901-25 so close....

I am assuming you are in the states so you would have a 110V transformer.  And being 18V instead of 14.4V, some of the component values would be different.  If I was Mr Black & Decker, I'd make the same boards and just change the tranny and the circuit values for different countries / batteries, but we can't assume....though you do say your board looks the same.

I'd say your first action should be to test the battery.  Use a power supply with current limit set at 100 or 200 mA. If nothing else, use a 24v DC supply with a limiting resistor of 47 or 56 ohms - not critical - but make sure it is a 1W or better type.   Charge the battery and the voltage should go up to around 21-23 volts after a few hours.  If it does, your battery is fine.  If it's low you have some shorted cells - the fact that your beefy resistor has burned out could indicate this.  The beefy resistor is actually only limiting the trickle charge.   22 ohms is a very commonly used value for this, so if it got burned the red bands might go brown and look like 11 (which is not a preferred value).

As your battery voltage is different I can't comment on what this resistor should be - but as it is only for limiting the trickle charge it should not be critical - you should be able to measure a current of maybe 20-50 mA when the battery is trickle charging.  If the resistor is burned you can't go by the colors, though 39 ohms sounds a bit high.   My 22ohm was the big white square one in the photo.  

Can you test transistors?  If so you should also try testing Q1, Q2 and D5.

This post could rapidly get huge so email me at stn564 (at) yahoo (dot) com (dot) au  if you want to discuss further.




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drill saver!!!! & advice if possible
monty44   6/14/2014 3:18:07 PM
Don, thanks for this post & the photos, I was looking everywhere for a post about the B&D 1hr charger, all the others I found are either for the wallwart slow charger or newer B&D charger, found your photo & then the post. 

I've got a B&D 18v drill with a similar looking 1hr charger (ref 486910-17), all of a sudden the charger stopped charging my 3 batteries, I would get the red light for a few minutes & then nothing.

Once I got past the security torx screws (a small blade screw driver did the job) I found the same circuit board as yours (I think), however where you show a 22ohm resistor in the slot, I had a very burnt resistor & am not entirely sure if its a 22ohm or greater. I put a meter a cross it & I get 39ohms.

After reading your post I also checked the connection you mentioned & yes it has dried out & come away...good spot that one.

I'm a novice with circuits, so not sure if the resistor has blown or should be 39ohm, reading the colours on the burnt resistor I would get an 11ohm which sounds wrong.

As my charger is for a 18v battery,  do you think this resistor is correct or should be a 22ohm, or maybe something else? everything else on the board does look the same.

I know its been a while since you posted this, but any adivce would be great. 


Don Tavidash
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Re: Potential Thanks!
Don Tavidash   10/31/2013 8:56:28 PM
Quickbadger - glad to be of help.   Apart from dry joints, check that the connection to the side of the battery is good - the silver bit you can see on the side of the upright black plastic thing on the small board in the 2nd photo.  It can move slightly and might not be contacting the battery, though I only had problems when "test-running" it with the charger out of the case.  I think the movement when you inster and remove the battery caused the wire to flex and cause the dry joint in the first place.

Always good to have a second drill - you can use one for drilling and one for screwing and not spend your life changing bits.  Good luck with it!


Don Tavidash
User Rank
Re: Your habit
Don Tavidash   10/31/2013 8:48:02 PM
The Drill probably ranks as one of my best finds.   Some time ago I found some obsolete "Grid-sense" units - they attach to power poles and sense the electric and magnetic fields from the wires, and if they go off they flash to enable faultfinding crews to locate the fault.   They each had a small solar panel, a xenon tube, lots of red LEDs, and all sorts of other bits to scavenge off them, and there were 5 of them.  Rich pickings!

I think your mother was right.  I don't pick up combs either.

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Potential Thanks!
Quickbadger   10/31/2013 2:56:11 PM
I have that same drill at home that died 10 years ago.  The battery charging issues sounds very familiar.  I have always meant to fix it, but have not touched it since I bought an 18v set.

Now I'm curious enough that I'm going to check this out.

Duane Benson
User Rank
Component level repair
Duane Benson   10/28/2013 11:58:33 AM
I've had a few experiences lately where I've been able to repair things that generally aren't considered repairable. One was an LCD monitor. I actually found a guy selling a small parts kit for, what is apparently a common problem with that type. I fixed a dead $120.00 monitor for $12.00. I've also repaired a bike computer and a few other items that I would have otherwise thrown away.

Years ago, just about everything was repairable, but that changed in the 1980's. I'm thinking that the tool sets, parts and information availability and overall knowledge has caught up with new manufacturing techniques such that people who are inclined, like you, can start treating a lot of devices as repariable instead of throw-away.

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Your habit
kfield   10/27/2013 10:26:20 AM
Hi Don - nice story about resurrecting a dead drill. I am curious, though, about your habit of rooting around in dumpsters. What's the coolest thing you ever found? I personally like to pick up interesting things I see when taking walks, but always remember my mother once saying "Don't pick up that comb, you don't know what disease that person had!"

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Keep those drills out of landfills
zeeglen   10/25/2013 11:18:38 PM
I've found it is often the bamn dattery that fails.  Good tale, (and good pen-name) Mr Don Tavidash :^}

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