3Com CP-1 owner manual Troubleshooting

Troubleshooting

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Problem Possible Cause and Solution

Muffled sound in L&R channels

Center channel sound muffled

Hum

Balance control doesn't work in Pro Logic or Stereo Logic

Panorama Calibrate isn't working

Interference with AM, FM, TV or Cable TV

Erratic recall of programs

When no center channel is used, the rear-panel phantom button must be pushed IN.

The center channel amp may be connected to the subwoofer jack on the CP-1 rear panel. Reconnect to Center Output jack.

Finding and eliminating audio hum in a complex installation can be a very frustrating task. Often, the easiest way to identify the culprit is to systematically eliminate devices from the audio chain. If Cable TV is connected to any equipment in the system, start by unplugging the Cable completely, preferably right at the wall jack. If this eliminates, or greatly reduces the hum, it's worth a call to your Cable company. A quick fix, assuming your cable is round 75Ω wire, is to attach a 75-300Ω transformer to the end, then attach a 300-75Ω transformer to that, so that the end is back to a round 75Ω wire. There are commercially-available antenna lead isola- tors which may provide additional insulation from electrical surges.

If there is no center channel in the system, the center channel output is routed to both the left and right main outputs. This means the left speaker reproduces not only the left channel information, but also the center channel information. If you set the balance all the way over to the right, the left channel information will be attenuated, but the center channel wll still be present at the left speaker. In other words, it's supposed to work that way.

Panorama is an interaural crosstalk cancellation program that produces an anti-phase cancellation signal to the opposite speaker. When the calibration mode is in LEFT ONLY, there is still cancellation signal coming out of the right speaker. This is a psychoacoustic phenomenon and LEFT ONLY means the calibra- tion signal should appear to come only from the left (usually to the left of the speaker.)

The CP-1 does generate minimal amounts of RF energy and is in compliance with FCC rules. If some interfering noise is noted, move AM loop and FM "T" type antennas away from the CP-1 and reorient them as necessary. Use shielded cable for FM and antenna feeds.

Severe power surges or sags can confuse the CP-1 memory. To correct, or if you simply want to start over, restore the factory defaults with the procedure described at the end of this section.

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