24 vdc Power supply problem.

This 3 week old electric drill has broken wires already. Picture on plastic case says center hole is positive. Both wires are broken off not sure which wire is which to the plastic case. If I solder wires on wrong will that kill the PS or the charging circuit inside the drill? Power supply says 24 vdc and me digital meter says 23.9 vdc. The case is glued together I wonder if it can be cut open. Harbor Freight does not sell extra PS.

Power supply label clearly shows the center pin is positive. Once re-connected, measure the voltage at the plug with DC voltmeter and make sure positive lead is in center. Should read +24VDC plus or minus a bit....
PS: Insulate the solder connections so they don't short against each other.

If it's only 3 weeks old, it should still be under warranty at Harbor Freight. But it doesn't look like "normal wear and tear."

No, it's either old, or it's been seriously abused.

It can certainly be repaired though, I find it's easiest to cut round the join of the two halves, with either a small hacksaw or Dremel disc - repair the unit, then glue it back together.

Nigel Goodwin said:

No, it's either old, or it's been seriously abused.

It can certainly be repaired though, I find it's easiest to cut round the join of the two halves, with either a small hacksaw or Dremel disc - repair the unit, then glue it back together.

Click to expand...

Plastic on the copper wire seems to be too hard when I bent it 180 degrees plastic insulation cracks open exposing the 2 copper wires. I have the bad wire repaired but I'm not happy with the ugly repair. VOM test shows center is 24 vdc positive and the electric drill is charging.

I have 3 more old power supplies from older electric drills that batteries will no longer hold a charge or drills are worn out and trashed long ago. One is 24 vdc, another 26 vdc, the other one 27 vdc. They all have different plugs that will not plug into my new electric drill. My ugly repair will have to make do for now. These tiny 7 strands of #28 copper wire are almost too small to work with.

The second adapter you show has identical ratings. You could change the plug end of it and use it if desired. Just verify the polarity at the plug end after soldering any wires.
Splicing an old plug (with long wire) mid way down the new adapter wire is a lot easier to work with than right at the adapter molding like the old adapter. Stagger the wires (offset by an inch) while cutting and splicing makes for a neater look, and makes insulating easier since no one wire can touch the other, even by mistake.

This is the reason I RARELY buy anything with a tail from Harbor Fright

7 strands of AWG 28 are adequate for 300 mA. Generally soldering the wire joint by staggering the cuts will result in the strongest mechanical joint with the thinnest sleeves using heatshrink tubing or coat with rubberized dip coating or silicone in a sleeve. Stress Relief is a critical requirement for all wire joints to avoid being too stiff or limp.

The bend radius near the rigid exit should be 2x larger than the radius of the wire with the same bend force.
This transforms the mechanical impedance of strain/stress between the rigid exit and the wire to minimize overstress failure of the insulation and wire with an optimal ratio.

Some types of inexpensive plastic become brittle with age due to a lack of nylon (polycarbonate) silicone or rubber in the blend.

Nigel Goodwin said:

No, it's either old, or it's been seriously abused.

It can certainly be repaired though, I find it's easiest to cut round the join of the two halves, with either a small hacksaw or Dremel disc - repair the unit, then glue it back together.

Click to expand...

That's what I would have done, worked fine for me in the past. A few drops of super glue and done for reassembly. When soldering always remember the bigger the blob, the better the job.

Ron