2. amps-preamps
  3. 191188-135431

What is causing false tube faults in VTL MB450 Series III?

I’m having trouble with one mono vtl amp which frequently signals a tube fault (red faults,green fault) requiring 2-4 reboots. The tubes were purchased  recently through VTL. The tube(s) responsible for the warning alert changes. After repeated restarts the amp performs as expected.The second amp with new tubes as well does not have this problem. Any thoughts? Thank you

michaeldouimette
carlsbad2's avatar
carlsbad2
1,602 posts
 

Swap the tubes between the amps and see if the tube fault follows the set of tubes.

 

michaeldouimette OP
1 posts
 

Have done that. Still same amp. Thanks

audioquest4life
770 posts
 

That’s strange. Have you isolated the amp from the preamp and speakers and repeated the power on sequence? Since the tube swap did not eliminate the problem, I suggest that you start from the basics…disconnect all things connected and start from scratch. Swap the power cord, if problem persists, swap to a new outlet, preferably, the one that your other amp is using. If problem still persists after having disconnected the speakers and preamp cables, and after swapping cords and/or outlets, then your amp is the culprit. If there are smaller signal tubes on the amp, repeat the tube swap process. Good luck. 

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