Hello, first of all I would like to give my compliments for this forum.....and apologize for my terrible English.
I'm an Italian vintage radio addicted and I own a valve tester AVO CT160, bought a decade ago.
I love this tester, but recently it has a problem for which I'm not able to find the reason.
In short: during the TEST process, the meter needle tends to dance at random, especially when the mA/V potentiometer is activated. This fact makes impossible to read correctly the valve efficiency on the green scale (the needle dance continuously).
I made the attached video to better explain the situation, that is the same with several types of valves (i.e EL84, ECL82, ELL80 etc.).
During the last days I've read a lot of pages about the CT160 on this forum, very useful to better understand the principles and the problems of this tester, but I didn't find anything about my problem.
I checked some parts potentially involved: RV1 (mA/V potentiometer), R14, R5, R2, R10 (anode resistor), the meter, some soldered joints, but in "cold" condition they seem OK.
Do you have any advice for me??
Many thanks for your help.
Roberto from Genova, Italy.
https://youtu.be/bbijzOw5uDU