Need a schematic

[yojo77]

I have an old "Simpson Multimeter" model 260, it has sentimantal value.
I cannot zero the Ohmmeter in the Rx1 scale, does any one know where I could get a schematic?
Thanks

 

[k7elp60]

Simpson 260

The first thing I would do is replace the D cell. It is used as I recall on the RX1 and the RX10 scales. If the battery is good, there is a resistor about
10 ohms(original value) that has changed value. I have replaced them with a 10 ohm 1/2W resistor.

 

[yojo77]

Schematic for Simpson Multimeter

Thanks for your suggestion.
The battery is ok, and the meter can be " zerod" in the Rx100.
In the Rx1 it can be adjusted to about two ohms.
Since you worked on this type of multimeter before
can you tell me if the ten Ohm resistor is under the variable potentiometer?. I checked the pot and it was ok.
There are many resistors in the small holes, and you can"t see the value unless you unsolder them one at a time.


Thanks

 

[Nigel Goodwin]

Re: Schematic for Simpson Multimeter

Thanks for your suggestion.
The battery is ok, and the meter can be " zerod" in the Rx100.

I don't know this particular meter, but on Rx1 analogue meters take LOTS! more current from the battery - so it's perfectly normal for it still to zero OK on Rx100 even when the battery is poor.

For this reason you must check the battery under load, it's no use just measuring it's off load voltage - test it under a decent load (few hundred milliamps), or better still check it by replacement.

If you've done all this - just ignore me :lol:

 

[yojo77]

Thanks for all the suggestions but I already have tried all that.