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Leon Crampin · 21st May 2012, 3:20 pm

Another Avometer and resistance range extension unit - irresistible at the price:

Avo Model 7 Mk 1 ser. 71145 - 24432.
Model 7 Avometer resistance range extension unit (no serial number).

The meter is in fair condition (dirty) and has been opened but not molested inside. It has the horseshoe magnet and the bimetallic slidewire temperature compensator which works beautifully. The 1 microfarad block capacitor for the capacitance range is is shunted by a waxed paper 50nF 500V component dated Feb 44. The scale plate of the meter has the letters KF hand marked in black ink on the rear and a paper disk is fitted in a recess in the back of the front panel near the block capacitor with 55 marked on it. The battery compartment is clean.

This instrument clearly dates from 11/45 but has a few problems - annoying because it's basically working and accurate. The pointer balance is miles out, probably due to whiskery corrosion growths on the MC terminations and balancing arms. The movement also sticks slightly at various points.

I am quite happy to remove the meter (and reset the cutout) but would welcome PMMs advice on clearing the whiskery growths and unsticking the movement. I have a steady hand...

Leon.

Are perished rubber Avo leads worth keeping?

21st May 2012, 3:20 pm	#867
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,874	Re: AVO Multimeter survey Another Avometer and resistance range extension unit - irresistible at the price: Avo Model 7 Mk 1 ser. 71145 - 24432. Model 7 Avometer resistance range extension unit (no serial number). The meter is in fair condition (dirty) and has been opened but not molested inside. It has the horseshoe magnet and the bimetallic slidewire temperature compensator which works beautifully. The 1 microfarad block capacitor for the capacitance range is is shunted by a waxed paper 50nF 500V component dated Feb 44. The scale plate of the meter has the letters KF hand marked in black ink on the rear and a paper disk is fitted in a recess in the back of the front panel near the block capacitor with 55 marked on it. The battery compartment is clean. This instrument clearly dates from 11/45 but has a few problems - annoying because it's basically working and accurate. The pointer balance is miles out, probably due to whiskery corrosion growths on the MC terminations and balancing arms. The movement also sticks slightly at various points. I am quite happy to remove the meter (and reset the cutout) but would welcome PMMs advice on clearing the whiskery growths and unsticking the movement. I have a steady hand... Leon. Are perished rubber Avo leads worth keeping?