chapter 5 • troubleshooting
TO ELIMINATE HUM IF THE ABOVE HAS FAILED:
A)Disconnect the power from all outboard devices and tape machines except for the
B)Plug in each tape machine and outboard effects device one at a time. If possible, flip the polarity of the plug of each device (turn it around in the socket) until the quietest position is found.
C)Make sure that all of the audio cables are in good working order. Cables with a detached ground wire will cause a very loud hum!!
D)Keep all cables as short as possible, especially in unbalanced circuits.
If the basic experiments don’t uncover the source of the problem, consult your dealer or technician trained in proper studio grounding techniques. In some cases, a "star grounding" scheme must be used, with the mixer at the center of the star providing the shield ground on telescoping shields, which do NOT connect to the chassis ground of other equipment in the system.
Line Conditioners and Protectors
Although the
•Line spike/surge protectors. Relatively inexpensive, these are designed to protect against strong surges and spikes, acting somewhat like fuses in that they need to be replaced if they’ve been hit by an extremely strong spike.
•Line filters. These generally combine spike/surge protection with filters that remove some line noise (dimmer hash, transients from other appliances, etc.). A good example is the Isobar™ series from Tripp Lite.
•Uninterruptible power supply (UPS). This is the most sophisticated option. A UPS provides power even if the AC
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