Mesa/Boogie Mini Rectifier Twenty-Five Owner's Manual page 14

A power tube short or failure is often the cause of a blown fuse. Position yourself behind the amplifier and follow the cold start procedure
mentioned in the STANDBY switch section of this manual. Watch the power tubes as you flip the STANDBY to the ON position. If a power
tube is going bad or is arcing you will often see it as you power up! Flip the STANDBY switch to Standby immediately and replace the
faulty power tube and the fuse as necessary.
If you see nothing abnormal as you move the STANDBY switch to ON, it is possible that a power tube shorted 'temporarily' and caused
the blown Fuse. Occasionally, whether from just luck or from cooling down, a short in a power tube 'reconnects' itself temporarily and
can operate normally again... but this tube should be considered faulty and replaced as soon as possible to ensure uninterrupted per-
formance. If you can identify a tube that is arcing or shorting by the method mentioned above and the tubes have minimal use, consider
replacing the obviously faulty or failed tube and leaving the others installed.
If you haven't changed tubes for a while after heavier use, this failure may be telling you it's time to change all your power tubes. Save
any working but used tubes as your new spares.
Spare fuses (of the proper type and rating) are a must for the fabled cord bag along with spare tubes. Always have both on hand – at
the gig or at home – since tubes decide when it's time to stop working. Spare tubes and fuses can be worth their weight in gold should
you ever experience a tube failure.
PAGE 14