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5.
Fasten the wall to the bottom of the chassis using two 6-32x3/8” black screws
installed from the bottom of the chassis and into the fasteners on the wall. Make
sure that the wires pass easily through the slots in the wall, and aren’t being
pinched.
You have now completed all the wiring and 99% of the assembly of the amplifier.
Visual Inspection
Check for the following items:
1.
Power Supply wiring from the power supply to both amplifier modules is in place.
2.
Double check the polarity of the power supply wiring!
Section 5: Testing It Out, Setting the Bias, and Installing
the Top
Be careful. The amplifier will be energized with the top off, and hazardous voltages
will be present in the amplifier. Use appropriate precautions to avoid injury.
Once the visual inspection looks ok and any shortcomings have been corrected, you can
perform the following tests.
Power-Off Tests
1.
Connect an ohmmeter to the left channel red and black binding posts. The
resistance should read between 900 and 1100 Ohms. The nominal value is 1000
Ohms.
2.
Connect an ohmmeter to the right channel red and black binding posts. The
resistance should read between 900 and 1100 Ohms. The nominal value is 1000
Ohms.
3.
Disconnect the ohmmeter, and set it to DC volts, in preparation for the next tests.
Power-On Tests
The only connections for these tests will be the AC mains power and/or the DC meter
used to measure voltages. Make sure to keep clear of the high voltage. Plug in the
amplifier and turn on the power. Watch it closely for one minute as you check for the
lack of smoke. Turn the amplifier off quickly if you see any smoke!
Most typically:
1.
The four green LED’s (two on each amplifier board) should light up.
2.
After about 7-10 seconds, you should hear the click of the speaker relays. If this is
successful, then perform the following additional steps.
Measure the following DC voltages, repeating the test for both the left and right channel
outputs.
1.
Measure the DC voltage between the red and black speaker binding posts (with no
speaker connected). You may see as much as 1 volt, which represents 1 mA of
leakage current in the large output capacitor flowing through the 1K bleeder
