• 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.

Yaqin mc10L

LED's may have gone short circuit. Try another pair as they are in series and known to fail. I doubt if the resistors have failed and you must have the supply else your output valves would be over heating like mad i.e. outside plates glowing cherry red!
 

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Hi, I always read you passionately! Greetings from Italy! I'm doing an upgrade on my 1995 mc10L, first series, the one with external capacitors ... at sight. I wanted to change the 4 x 470uf 250v 85 ° capacitors with 4 x 680uF 450V 105 ° C Kendeil K05 LONG LIFE LOW ESR TUBE AMP AUDIO CAPS. I was wondering if you know that the rectifier bridge can hold bigger capacitors, in this case from 680uf ... I don't want to do damage also because the rectifier bridges are really hidden and impossible to reach! I have some doubts that we can mount 4 x 680uf because on the PCB there is' written 330uf..so I think that already bigger capacitors have been mounted than expected. I hope for your answer!
 
Hi, it's safe doing no feedback mod (cut capacitor+resistor leg) without applying triode mode (original UL)? From previous posts it was clearly evident applying after T. mod.

Q.2,, for triode mode, I need add a 100 ohm resistor to ground right after disconnection from OT?

Thank you
 
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