simson 377 voltmeter

Discussion in 'General Electronics Chat' started by electronis whiz, Aug 9, 2011.

  1. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
    i have an old simpson anolog voltmeter. it works but it is a bit wierd. it was working but aprox 1/2 V off even though the scale is calibrated. so i took it apart and there was a clothe wire wound resistor. the wire came off of the one terminal of it so i soldered it back on and it worked ok. but it has 1, 2.5, 5, 10, 25, 50, 100, 250, 500, 1000 V DC. the 1 volt position conects - of the meter direct to - terminal post, all rest use a series of resistors, so the meter mechinism apears to be 1 volt.
    the problem is any position under 25 v makes the meter show almost double or triple reedings. but at 25v a lantern battry, 9 volt show up acuratly. i'm thinking its a resistor problem somewhere between 1-10 V. i'm thinking one of the wirewounds for 2.5&5v are shorted out. because else it should have not worked at all with a broke wire. but it shows 1.5 K ohm. i have not found any schematics or any info on it other than posibly a 1951 model. it is a model #377. i would like any sugestions on what value resistors thre should be.
  2. Jotto


    Apr 1, 2011
    You most likely lost a diode, geranium diode. Its easy to fix. An then I read more of your post. My 260 didn't have many resistors inside of it, but of course was a newer model.

    Might try a resistor wheel and see if that works.