Precision 910 resistor values

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Precision 910 resistor values

Postby Arno P » Mon Jan 16, 2017 9:49 pm

Got this tester and was not functioning properly and I checked each resistor with the schematic next to it. Guess what, the values mentioned in the diagram are very often 1000x higher (M ohm mentioned whereas kOhm is on the colour code on the resistors and is the measured value corresponding with these colours. The resistors are the old types, not resoldered or anything. I found a defect one of 500 Ohm, replaced it and the tester gave the right values again.

Question, did anyone else notice this "mistake" or difference between schematic and the actual components?
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Re: Precision 910 resistor values

Postby Admin19 » Mon Feb 06, 2017 7:27 pm

Arno,

A factor 1000 is a bit suspicious. Old color codes are sometimes not the same as we have now. If it was a factor 300 or 600, I would say the resistor is defective. But 100 or 1000.... it can be older color codes.

Carbon resistors are long time instabile. If you see them with silver tolerance, they are useually far more off than gold tolerance. From that you can see they knew 60 years ago, how to make long term stabile carbon resistors, but the company building the tester, took the cheaper, silver ones. Gold tolerance types can be good, so within 5% still, but take care, as such may be choosen at places where precision is needed, or lang term stability was needed. Silver types are useually way off tolerance. Like +20...40%. Always going up. With Caps, if you can't verify them, check if they hold the charge, same as a new cap of similar value and type. If not, replace them.
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