Simpson VU meter repair

[BossOrgan]

Hi all,
I am restoring a Raytheon RC10 tube broadcast console from the 1940s. The large (4") Simpson VU meter is not working.
I have taken the meter apart, and inside the meter there are two wirewound resistors. The resistor that attaches to the + input terminal is open. I am trying to find out the correct value for this resistor. Can anyone help me?
Thank you
Tyler

 

[rayma]

This RC-11 manual has some RC-10 info, but only this much on the meter:
VU Meter: 0-1 ma DC Weston Model 862
https://www.steampoweredradio.com/p...nsole/Raytheon RC-11 Audio Console Manual.pdf

Since most such meter movements have a basic 50uA sensitivity, you should be able to calculate
the value of the bad resistor from the value of the good resistor and the 1mA full scale spec.

 

[HollowState]

These meters have an internal rectifier assembly like all "real" VU meters have. I just happen to have one of these near by. So I opened it and measured both resistors. The one on the right measures 1.099K ohms. So it's safe to call it 1.1K at probably 1%. The other resistor at the top goes across the rectifier and measures 718 ohms in one direction and 2.810K in the other. All values include roughly 3 ohms lead resistance. Hope this helps. (Had I used one of my Agilent DMMs I could have nulled that out, but the B&K DMM was more handy)

 

[BossOrgan]

Hollow State, thank you very much!!!!
Tyler

 

[PRR]

This RC-11 manual has some RC-10 info, but only this much on the meter:
VU Meter: 0-1 ma DC Weston Model 862
.....
Since most such meter movements have a basic 50uA sensitivity...

Where do you see "1ma"?

IIRC, the customary sensitivity was 200uA. (They are not quite as fragile as the 50uA meters found in high-end VOMs.)