AVO VCM MK2 meter specification + LCD replacement

AVO Ltd London made VALVE TESTERS.

AVO VCM MK2 meter specification + LCD replacement

Postby Valvelover » Sun May 29, 2016 4:57 pm

Hi.
Being new to this forum, I have a question regarding the meter used in theMK2.

My meter seems to be unstable - needs "zero adjust" constantly and sometimes the needle even gets stuck somewhere on the scale. My conclusion is, that it needs to be replaced.
I have been inspired by a brief description of the installation of a 3½ digit digital meter on a MK4, and would like to perform the same on my MK2.
Was thinking that having an low offset opamp circuit in front of the digital meter should do the trick, but I am a bit in doubt about the specifications of the original meter. Read somewhere that the MK2 meter is a 100uA FSD and somewhere else, that it is actually a 440uA FSD type - which one is correct?

I have tried to measure the data for my meter (that behaves odd from time to time), and I ends up with 172uA FSD and an internal resistance of 117ohms. This value doesn´t seem to fit with either 100uA or 440uA.

I hope that someone can share some light on the meter data and would be thankfull in case some informations regarding a suitable opamp circuit should show up as well.
Valvelover
 
Posts: 1
Joined: Sun May 29, 2016 4:43 pm

Re: AVO VCM MK2 meter specification + LCD replacement

Postby Admin19 » Mon Feb 06, 2017 7:00 pm

sorry, I read your question a bitt late. The meter appears to have magnetic particles inside, and perhaps loss of anti static treatment. When both problems come together, the meter behaves like you write. That can be repaired. Check the pricelist for item 624-022 (small overhaul).
User avatar
Admin19
Site Admin
 
Posts: 65
Joined: Sun Dec 11, 2011 1:55 pm


Return to AVO

Who is online

Users browsing this forum: No registered users and 1 guest