Dayton 4X221 Snap-Around Volt-Amp-Ohm Meter

Mad Phil forced me to take this little gem:

Dayton 4X221 Snap-Around Ammeter

Dayton 4X221 Snap-Around Ammeter

Judging from the much-folded Dayton 4X221 Snap-Around Ammeter Operating Instructions (a scanned copy that I folded around the original and tucked inside the case), the ammeter dates back to 1979, which says Mad Phil probably used it in the early 80s, when he was repairing AV equipment. Unlike most vintage clamp-on ammeters, this one can also measure voltage and resistance:

Dayton 4X221 Snap-Around Ammeter - Specifications

Dayton 4X221 Snap-Around Ammeter – Specifications

The resistance function requires a single AAA alkaline cell in the bulky probe, so this should come as no surprise:

Dayton 4X221 Resistance Probe - battery contact corrosion

Dayton 4X221 Resistance Probe – battery contact corrosion

The probe housing contains a 1 A fast-blow fuse, which blocked the corrosion from getting deeper into the probe tip:

Dayton 4X221 Resistance Probe - battery and fuse

Dayton 4X221 Resistance Probe – battery and fuse

The AAA cell was “Best if installed by Jan 1999″, which I’m sure was true. Somehow, you never recognize the last time you use something; I suppose old instruments get used to not seeing the light over the workbench after a while.

Anyhow.

Douse the corrosion with vinegar to neutralize the potassium hydroxide, rinse out the probe body, polish the top of the fuse, buff up the battery contact on the test lead, and it’s all good again.

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  1. #1 by Red County Pete on 2013-03-24 - 13:51

    Urggh, I need to check the flashlights, especially those in the trucks. (Amazing how many flashlights we use. I think it’s a country thing.) The Robo-Toolz company (IIRC, since sold to Porter-Cable) got my mitigated respect for the easy to remove batteries from the laser-level unit. They lost points for needing a screwdriver to get the 9V battery out of the transmitter. One of those tools not used often, but non-trivial to fix and too expensive to ignore.

    • #2 by Ed on 2013-03-24 - 16:23

      I need to check the flashlights

      Me, too… I can’t wait for lithium cells to get cheap enough to displace alkalines and NiMH cells.

      (Somebody pointed out the special-purpose lithium cells that can replace two alkalines, but … not at a rational price, at least for me.)