Stereo Amplifier User Manual

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Troubleshooting 7
®
Troubleshooting
©2004 PS Audio International Inc. All rights reserved.
Owner’s Reference A-100 Power Amplifi er
to reconnect the amp and move further down the chain. If you were working with a receiver or an
integrated amplifi er, you will need to jump to step 4. If you have a preamp, or processor that is feeding
the power amp, your next step would be to disconnect all inputs to the preamplifi er or processor. Once
these are disconnected, and the preamp or processor is connected only to the power amplifi er, turn
the system on and again, listen for hum. Should the hum now appear, it is a problem with your preamp
or processor or their interaction with the power amp. Before returning the preamp or processor to
the manufacturer, try a cheater plug to break a ground loop. Cheater plugs are simple devices that
convert a three prong AC plug into a two prong AC plug and in the act of converting three prongs, to
two prongs, they disconnect the ground from the wall socket. Try one of these on the preamp, or the
power amp, or both.
If you determine that there is still no hum present when the preamp, processor or receiver is
connected with no inputs, then selectively begin plugging in your various inputs one at a time. After
each connection, check for hum until you discover the humming culprit.
VCR’s, surround processors, and any device that is connected to a television cable or satellite dish
can cause a loud buzz and should always be suspect. If, by the process of elimination described
above, you determine it is a component like a VCR that is causing the hum/buzz to occur, and using
a cheater plug or removing the ground pin on a PS xStream Power Cable doesn’t help matters, it may
be necessary to isolate the cable connection (CATV) with an isolation transformer. This inexpensive
device is available at most Wal Mart, Radio Shack or department store type outlets and is sometimes
called a ‘matching transformer’. If you have problems fi nding one, call your local cable TV company
for advice. The matching transformer will be placed between the cable TV cord and the VCR, TV or
processor.
Just remember, take the system down to its simplest level of connection. Find a way to hook the
system up with as many pieces of the system missing or not connected. Keep it simple and get it
to the point where the hum’s gone. Then start adding back components one at a time until the hum
returns.
Finding the problem is 9/10th of the work in fi nding a solution.
If you have a problem connecting a subwoofer, please refer to the quick start guide in the front of
this manual. We do not recommend connecting the high level inputs of a self power subwoofer to
the outputs of the A-100 Power Amplifi er. For many subwoofers it will be fi ne. Some, like the REL
subwoofers, and the Carver Sunfi re type of subwoofers will not work properly when connected to the
A-100 Power Amplifi er’s outputs. This is because the A-100 is a balanced type of output with a DC
voltage as referenced to ground.
If the A-100 shuts off when playing music, there are several possibilities. If the music plays quite loudly
but shuts off on the most explosive parts of the music of video soundtrack, then the A-100 Amplifi er is
probably underrated for the type of speaker you are using. See your dealer or call PS Audio for advice
on going to the next size power amplifi er.
If the amplifi er shuts down with very little volume, then check the speaker cable connections. The
Finding a ground
loop
Try a cheater plug
Process of
elimination
It could be the
cable TV
Problems with
subwoofers
If the amp shuts
down while
playing music