Ancient Micronta R-4002 VOM

I somehow ended up with this ancient Micronta R-4002 VOM. It's an interesting very early Radio Shack VOM. It says "1955" on the meter card, right next to the handwritten serial number. It's 20,000 ohms per volt for DC, 8,000 ohms per volt for AC.


The front is Bakelite ...


... and the back is drawn sheet metal with black wrinkle paint. The left side of the top has a nasty crack right up to the top of the meter bezel.


It's missing one of the pair of screws that holds the front and back together. The knob on the range switch has taken quite a beating.


There's a crack on the right side, too, at the top right corner of the meter bezel.


Five DC voltage ranges, six AC voltage ranges, four resistance ranges, and four DC current ranges. The sixth AC range is the sensitive 5 dB range, which uses a separate input jack.


Here's a nice view of the meter scale.


The back has four feet formed into the sheet metal.


It still has a couple of old Everready AA cells  soldered in for the resistance circuit. I really should remove them before they cause any more corrosion damage.

The meter case is cast integral to the front panel. I'm not sure how I'm going to get it apart for cleaning.


The components look like they are of decent quality - all wirewound resistors. The construction is unusual - it looks like some kind of punched phenolic board with occasional eyelets.


The right-side crack in the top is visible here ...


... and here's the left-side crack. Must have taken a good fall.


The back has a cardboard lining. The old batteries left a bit a leakage on it.

I haven't tested it. If I recall correctly, the meter needle wouldn't zero. I think I need to open up the meter anyway to fix the crack in the Bakelite top.

© Steve Byan 2011-2019