UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

waran2005 · 7th Feb 2023, 3:51 pm

Hi all,

Just doing a few checks on my VCM 163, after removing the meters from the VCM and checking current required for FSD, the Ia meter indicates FSD at 21 uA and the mA/V meter indicates FSD is at 35 uA - am I missing something obvious here? These are not doing what I expect, shouldn't FSD be at 50 uA for both these meters - any ideas?

Meter resistance values are correct, the low uA required for FSd would also explain why the meters are off scale when selected to check AC, MA/V.

I have replaced the set AC / current meter with a 2.4k resistor as I don't want to damage it during circuit testing, the current measured is around 45 uA which is I believe required for the meter pointer to reach the set AC / calibration position

Any help appreciated.

7th Feb 2023, 3:51 pm	#1
waran2005 Tetrode Join Date: Feb 2020 Location: Cardiff, Wales, UK. Posts: 65	AVO VCM 163 Meters Hi all, Just doing a few checks on my VCM 163, after removing the meters from the VCM and checking current required for FSD, the Ia meter indicates FSD at 21 uA and the mA/V meter indicates FSD is at 35 uA - am I missing something obvious here? These are not doing what I expect, shouldn't FSD be at 50 uA for both these meters - any ideas? Meter resistance values are correct, the low uA required for FSd would also explain why the meters are off scale when selected to check AC, MA/V. I have replaced the set AC / current meter with a 2.4k resistor as I don't want to damage it during circuit testing, the current measured is around 45 uA which is I believe required for the meter pointer to reach the set AC / calibration position Any help appreciated.