• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Ayon Spark 2 - Always on mute

Hai everyone
i am a new member and i am new to valve amp and have bought a used Ayon spark 2 from a friend which worked perfectly for a few hours.
Next day when i started it it was on mute the moment it turned on. Bias was at 150mv. Out of 10 times i tried to use it it worked 2 times. I started looking for a technician and could find none near my area of residence. Now i though it might be the tubes and changes the tubes as well. Still its the same and yes i did bias it at a 100mv for the new tubes. tried turning it on without input aswell. Tubes currently in use are ullynov 6c33c-b
So friends help me troubleshoot this issue.