Mesa 50/50...no output

[JustMike]

 it fires up, tubes glow but no output on either channel. Where should I begin? The owner said he had the (original) tubes tested and they were good , but even so, if I don't see any red plating or dead filaments, I should hear something, right?

[sluckey]

Need more info. Ask the owner some more questions, like how did it die. Get some voltage readings. Find out what is working and what is not working.

[HotBluePlates]

Get some voltage readings.

+1.

When taking voltage readings, listen to the speaker. Start at the output tube plates for your measurements, and check for d.c. volts.

When probing plates & grids, you might hear a little "pop" in the speaker. As you work your way backward to the input jack, the pops will get louder. make sure volume controls are up a little way when you probe a tube stage before a volume control.

When the "pop" stops, but the volume control is up, you will have found a problem (either see no d.c. volts on a tube; or an open connection like a burned trace, loose connection, or open coupling cap; you might also find a short to ground at a coupling cap or tube grid).