Shopvac Model 500A Motor Wire Repair

The Shopvac Model 500A (1.25 HP!) inhaling dust from Tiny Bandsaw didn’t start up when I flipped the switch. It had been making horrible noises, but Shopvacs typically sound like they’re on the ragged edge of death, I wear 30 dB earmuffs when it’s running, and that wasn’t the problem anyway.

It turned out the hot (black) wire lead to the motor burned up:

The neutral (white) wire over on the left side looked just fine:

But the hot wire connector was toasted:

As the connector failed its resistance went up and so did the wire temperature, as shown by the plastic case:

With barely an inch between the motor armature and the failed connector, this became a zero-Mulligan repair:

I clipped the failed connector off the wire, very carefully sanded off the burned insulation, then gingerly crimped the business end of a ferrule around the wire + a doubled length of 22 AWG hookup wire:

Doubling the wire brought it up to 19 AWG, a bit larger than the 20 AWG armature wire, and maybe improved its durability. The ferrule surely isn’t rated for this sort of abuse, so I eased some solder into its end in the belief that any amount of solder is a better conductor than a similar amount of air.

Crimp the other end of the hookup wire into the business end of a solderless ring terminal along with the hot wire, anchor the ferrule to (and insulate it from) the armature with a wrap of silicone tape, do the same around the ring terminal, then squirt hot melt glue into the ruined connector housing to keep the wire from flopping around:

If it gets hot enough to melt the hot melt glue, there are other problems about to happen.

Reassemble in reverse order and the Shopvac once again makes its on-the-eve-of-destruction whine while inhaling chips.

A slip of tape marked “$5” fell off during this process, reminding me it was a garage sale find from quite a few years ago: saving it from an early grave may be an overall Good Deed.