Orban 5950 Technical Manual Troubleshooting 5-1
Section 5: Troubleshooting
Problems and Potential Solutions
Always verify that the problem is not the source material being fed to the 5950, or in other parts of the system.
RFI, Hum, Clicks, or Buzzes
A grounding problem is likely. Review the information on grounding on page 2-1. The 5950 has been designed with
very substantial RFI suppression on its analog and digital input and output ports, and on the AC line input. It will
usually operate adjacent to high-powered transmitters without difficulty. In the most unusual circumstances, it
may be necessary to reposition the unit to reduce RF interference, and/or to reposition its input and output cables
to reduce RF pickup on their shields.
It is not recommended to use a long run of coaxial cable between the 5950 and the exciter as a ground loop may
inject noise into the exciter’s composite input—especially if the exciter’s input is unbalanced.
The AES3 inputs and output are transformer-coupled and have very good resistance to RFI. If you have RFI
problems and are using analog connections on either the input or output, using digital connections will almost
certainly eliminate the RFI.
Unexpectedly Quiet On-Air Levels
The ITU412 multiplex power controller may have been turned on accidentally.
The 5950 may be in stand-alone stereo encoder mode. The active on-air preset determines this.
The 5950 may not be controlling peak modulation as desired. See the next topic below.
Poor Peak Modulation Control
First, if you are using the analog or digital output to drive the transmitter, make sure that this output is not
receiving the MONITOR.
The 5950 normally controls peak modulation to an accuracy of ±2%. This accuracy will be destroyed if the signal
path following the 5950 has poor transient response. Almost any link can cause problems. Even the FM exciter can
have insufficient flatness of response and phase-linearity (particularly at low frequencies) to disturb peak levels.
Digital STLs using lossy compression algorithms (including MPEG1 Layer 2, MPEG1 Layer 3, Dolby AC2, and APT-X)
will overshoot severely (up to 3 dB) on some program material. The amount of overshoot will depend on data rate
— the higher the rate, the lower the overshoot.
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