Page 49 - Triwatt Custom Lead Amp Builder's Guide

With the bias set correctly, you can now test all the voltages and compare them with the voltage
chart. Measure and write down the B+ levels at each filter cap. Also write down cathode and plate
voltages at all stages and also the screen grid voltage at the power tubes. Compare all the DC
voltages to those on the supplied Voltage Chart. As a rule of thumb, the triode gain stages should
have ~1V on the cathode, 0V on the grids and ~1/2 to 1/3 B+ on the plates. If the DC voltages
are not in the ballpark (within 50% of the general rule just stated), take some time to check the
circuitry of the offending stage. If you have a cathode follower in the signal path, the grid should
be at the plate voltage of the previous stage and the cathode should be about a volt higher.

If all seems in order, and the fuse has not blown, turn the volume up a bit. Plug in a guitar input
cable, and touch one end. You should get a louder hum, this is a good sign. If you get this far, it’s
time to plug in your guitar and take the amp for a test run.

Hopefully, there are no problems but if you think there are e.g. hum, squeal etc., then move on to
the troubleshooting section of this manual.

TrinityAmps TRIWATT Builders Guide Ver. 2.31.docx- 49 -