Avometer Model 7 Mk2 Meter Movement and Dial

The Model 7 Mk2 has a wonderful feature rich dial that I always loved, but unfortunately, they made the dial much simpler with the Model 8 Avometers. The Model 7 dial is a metal plate with a thin coat of white paint onto which they have printed the scale. Over time, the paint can turn yellow and even chip off. Sometimes if the needle scrapes the dial, then that area will have paint missing, and it is usually an indication that the meter movement requires balancing.

On my meter, the dial had yellow marks caused by fingerprints left by the factory workers. Over the years, the oil and bacteria left on the dial turns yellow, and you can see it. I used a gentle mix of windscreen wash and water to clean the dial and managed to remove the yellowness. I also cleaned the mirror plate behind the dial, and both sides of the glass.

One of the interesting design features of the AVO meter movement is the coil springs that it has at either end of the pivots. Each spring produces an almost equal and opposing force, and the idea is to have this force balanced so that the needle glides back to the home position slowly and effortlessly. In order to balance the force produced by each spring, there is a screw adjustment at each side of the pivot.

Usually cheap meters have only one spring, which makes the needle shoot back to the home position. A meter such as this can damage easily if it passes heavy currents because the tension in the spring can change preventing it from returning fully to home position. Many cheap meters have no provision for balance calibration, and consequently are disposed.

If you are unfortunate to acquire a meter that needs a new dial, then it may be possible to use the image given here. You will first need to resize the image through whichever printing application you have so that when you print it, it is the same size as the original dial.

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