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c. Feel the heat-sinks. There should be no appreciable heating.
6. In all but a very dark room, the LED soft glow should be invisible. If the LEDs
glow brightly in a well lit room, you have probably mis-loaded some resistors.
If there is neither smoke nor excess heating, leave the power on and move on to Test #2.
Test #2
1. If you have a DC voltmeter, check the voltage on the speaker outputs.
a. Left channel red to black binding post should show a DC voltage of less
than 100 mV if the amp has been on for about 1 minute
amp is on, the lower the DC output voltage will be.
b. Repeat this test for the Right channel speaker binding posts.
If this result is ok, go on to test 3. If this result is not correct (e.g. speaker binding posts
have a few volts of DC after the amp has been on for more than 1 minute), then re-check:
• Polarity of C7
• R17 is installed and has the correct value (2870 Ohms)
• That one of the OGND terminals has a ground wire installed.
Test #3
1. Hook speakers up to the binding posts. There may be a very soft click as you
hook up the speaker.
2. The speakers should be rather quiet at this point, perhaps with barely audible hiss
or hum if you place your ear near sensitive speakers. Any more noise than this
probably indicates either an assembly error or a power supply problem.
Test #4
1. Turn off the amplifier power.
2. Connect your preamp output to the power amplifier input.
3. Turn down the preamp volume.
4. Turn on the amplifier power. You may hear a soft click or thump from your
speakers.
5. After about 15 seconds, turn up you preamp volume to the desired listening level,
and enjoy your amplifier.
The amplifier has special slow turn-on features that diminish pops and clicks in the
speakers at turn-on without the need for relays. The DC bias voltages in the amplifier will
thus take 30 seconds or so to reach steady state. During that time, you may hear some
distortion. Don't worry, it will clear up perfectly in 30 seconds unless you are over-
driving the amp, or something is wrong. Think of it like a tube amp...it takes 30 seconds
to warm up.
2
The DC voltage will drop to very nearly zero in 15 seconds if a speaker is connected.
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2
. The longer the
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Troubleshooting
