Specifications

You are almost finished. And although the first temptation is to plug in the amp and
turn it on, I recommended taking the time to review all of your work. Any errors are
more likely to stand out during this time. It is common to find two or more errors.
After verifying the connections are correct, read all of the following steps before completing
any of them. Once you have finished reading these steps, it is time to begin. All of the
following voltages are measured with full 120VAC wall voltage applied.
Step 1 - Install a 2A, fast blow fuse into the fuse holder and a lamp in the lamp holder.
Step 2 – With the amp unplugged and no tubes installed, turn on the amplifier's power
and standby switch (or in this case the “ground” switch, turned toward the word “ground” on
the chassis).. The power and standby switches will remain on until all tests are finished.
Step 3 – Plug the amp's AC power cord into AC power at the wall.
Step 4 – The panel indicator should illuminate. Monitor for any smoke, unusual odors or a
blown fuse or physically hot power transformer. If anything unusual occurs, disconnect power
immediately and review connections.
Step 5 – If there is nothing unusual after a couple of minutes, remove AC power by
disconnecting the AC power cord from the AC source. Leaving the amp's power switch “on”.
Step 6 – With the amp still disconnected from AC power, install the tube rectifier.
Step 7 – Plug the amplifier's AC power cord into the AC power source at the wall.
Step 8 – The panel indicator should illuminate. Visually verify that the filament inside the
rectifier tube is glowing. Monitor the amplifier for any smoke, unusual odors or blown fuse. If
anything unusual occurs, disconnect power immediately and review connections.
Step 9 – With your multimeter on the 500 volt DC range, connect the meter's black lead to
chassis ground (photo 8.1a) and carefully connect the red lead to the positive end of C12
It is good practice to use a power strip with a circuit breaker and an on/off switch between
the wall power and the amplifier power cord as an improved electrical safety measure.
CAUTION
In case of any troubles, quickly disconnecting the power cord from the wall (or turn off the
power strip). You should not touch the amp or the amp's power switch until the amplifier's
power cord is no longer connected to AC wall power.
WARNING
CAUTION
Use of any fuse larger than 2A is not recommended and could cause severe and costly
equipment damage in case of an internal component failure.
Within a minute or two, the rectifier will have heated up and provided a slowly increasing high
voltage to the power supply. This voltage will properly form the high voltage filter caps.
NOTE
I personally recommend using a variable AC with separate current and voltage meters. This
allows bringing the voltages up very slowly and provides more accurate monitoring
capabilities.
NOTE
If you are uncomfortable with just turning on the amp and watching for smoke, I recommend
building an inexpensive Dim-Bulb tester to monitor and control current flow into the amp. A
quick internet search on “Dim Bulb tester” will give several diagrams and plans.
NOTE
When changing or installing a fuse or lamp, always remove the AC source by unplugging the
amp. Never use fingers to remove or insert a fuse into a fuse holder. Instead, use the fuse
cap to hold the fuse when removing or inserting into the holder.
WARNING
8.1
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Testing
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