06/27/2025
A Tale of Two Boogies™. While repairing this .50 Caliber, I noticed a major layout mistake by Mesa. The screen resistors are mounted tight to the circuit board, and they cross over two board traces on their way to the orange wires and the tube sockets. If a screen resistor were to burn up, which is a VERY common failure, the damage to the circuit board could be catastrophic. This amp wasn't here for screen resistors, but part of my job is preventing bad things from happening before they happen. So I mounted them up in the air, vintage Fender style.
The very next amp on the bench, a Dual Rectifier Solo 100, has a burned up screen resistor! How's that for synchronicity? This was a violent failure. Would have been lots of smoke, and the tube socket cracked into pieces. Don't see that too often. Luckily, Mesa used a better board design on this one, and after some clean-up, there is no board damage at all. New resistor and socket, and all is good.
