Page 47 - Triwatt Custom Lead Amp Builder's Guide

10 Power Up

REMEMBER: DO NOT OPERATE YOUR AMP WITHOUT A LOAD

The following the procedure to follow for the first power up of a new amp. Don’t give in into the
temptation to "fire it up" as soon as the last solder joint is cold.

Complete all the basic circuit checks already mentioned before soldering the transformers into the
rest of the circuit. If you haven’t performed the Power transformer test, go back and do it
now. If you've already soldered in your trannies, take a minute to desolder the secondaries from
the rest of the amp and go back and test them.

Install a 2 AMP SLO BLO fuse.

Note: If you see or smell smoke when you turn on the amp, turn it off immediately and re-check
the connections. It is common for new tubes to emit an odour upon initial start-up.

Test the 6.3 AC filament voltages and ensure they are on the correct pins for all tubes. Remember
this is AC voltage, not DC so set your meter.

THIS IS IMPORTANT: Before powering up INSPECT DIODES & FILTER CAPS. You
MUST have the diodes and cap polarities correct. This is critical but an easy mistake. If either
the diodes or caps are wired in reverse, you can destroy the caps, diodes and possibly the power
transformer!

If all is OK, install solder the power transformer leads to the turret board following the layout in
the above “Power Supply Wiring” section and the main layout as well.

Power up the amp and watch the following things as quickly as possible and roughly in this order:
 pilot lamp comes on brightly; and
 High Voltage secondary goes to nearly the same value as it did with the lines unsoldered

If any of these does not happen, shut off the amp immediately and find the problem by looping
back to the beginning of this checklist. If these check out, power down. B+ MUST be discharged
to safely continue messing with the amp guts. The included bleeder resistor will take at least a
minute to bring B+ down to safe levels.

Now hook your DC voltmeter to B+ and ground. Power up again and check the B+ voltage. With
no tubes installed, all the filter caps will charge up to the same voltage. The voltage should be very
close to 40% higher than the raw AC. Assuming you measured, say, 700VAC across the full
secondary in the above steps, then each half is delivering 350VAC. B+ will be ~40% above this,
which is ~490VDC.

TrinityAmps TRIWATT Builders Guide Ver. 2.31.docx- 47 -