So I couldn't resist a MV Twin Reverb that was on Craigslist for $200. It had blown the fuse, so I took one with me along with a light bulb limiter. It powered up with a new fuse and made a sound, so I grabbed it. I get it home and dig into it, and when I plug it in without the limiter, the fuse goes. Here are some voltage in various states: With all the power tubes pulled, the fuse stays, and the limiter is barely glowing. The limiter is slightly brighter with the standby in the operate position. The fuse does not pop when plugged in without the limiter and all power tubes pulled. Pin 2 of power tubes: 2.38vac Pin 3 of power tubes: 342v Pin 7 of power tubes: 3.08vac With the power tubes in, the fuse pops when amp is plugged in without the limiter. With the limiter, the fuse stays, but the limiter glows brighter than it did with the power tubes pulled. Still not full brightness though. Marked difference in brightness with standby in the operate position. I'm getting sounds out of it like this, but they're not pretty. The bias probe says I'm drawing 12.3ma on the power tubes. Pin 2 of power tubes: 1.67vac Pin 3 of power tubes: 171v Pin 7 of power tubes: 1.68vac The amp is generally clean, and doesn't look like it has been abused or wet. One filter cap has been replaced, the rest are original. Tranny dates are '75. Any ideas? Am I right that if the fuse doesn't blow with the power tubes pulled, then I'm likely to not have a blown PT? I unfortunately don't have a new quad of 6L6s handy.