Avo multimeter model 71

This meter was soon superseded by the more accurate and virtually identical model 72. which does not have the 1Amp fuse but otherwise much the same.

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There are four thick film resistor circuits housing the majority of the resistors which form the universal shunt, voltage dividers etc

The meter movement was OK but failed to give any indication on the DC voltage ranges. I found one of the section of the voltage divider thin film resistor was open circuit and another was considerably lower than it should be and a previous owner had already soldered a replacement for another open circuit section of the same thick film circuit. I also have a model 72 with an open circuit meter so I exchanged the meter and scaleplates to get a working instrument. This one will remain as a donor for spare parts.

model71

Three of the thick film circuits are on the underside of the printed circuit board


The versatile moulding for the meter and batteries has holes for additional sockets so that it can be used for the other meters in the range. This model was soon superseded by the more accurate and virtually identical model 72. The 1A fuse was omitted in the Model 72.

You will find more information here about these instruments and other similar models. AVO produced a range of the smaller multimeters such as this which are described here  

 

AVO produced the "70 series" range of analogue pocket meters with 2000 Ohms/Volt sensitivity and 3 inch scale lengths at the beginning of the 1970's. The following is from a 1972/3 trade catalogue.   

 


For further information have a look at my pages on similar AVOmeters here