USL JSD-60/80/100 - Hum in audio
The QSC/USL JSD-60, 80, and 100 cinema audio processors have a built-in emergency backup digital to analog decoder. This is intended for use if there is a catastrophic failure of the JSD unit. It gives a "down and dirty" sound output sending a mixed mono signal to the left and right amplifier outputs. This bypass mode is activated when the main power switch is turned OFF. This bypass is not powered by the main power supply but rather by an external 12VDC 1.25A AC adapter that was supplied with the unit.
We have observed several instances where either an incorrect AC adapter is used or the supplied AC adapter is failing. This may manifest itself as a loud "AC" hum over the sound. This can be diagnosed by unplugging the AC adapter on the back of the unit. If the hum goes away the cause of the problem is the AC adapter. If the problem persists other possible causes must be considered.
If the AC adapter fails it is a relatively easy unit to source. It is important, however, to use a good grade unit as lesser units may have a rough, poorly rectified output that would cause hum or noise in the system.
Related Articles
USL JSD-60/100 - No digital cinema sound
While this article is written for the JSD-60 and JSD-100, the same principles apply to the USL JSD-80 and the DTS XD-10P (which is a rebranded JSD-80). In order for digital audio to work one of the devices, generally, the sending device must ...
USL JSD-60 won't switch modes
There is a known issue with the JSD-60 processor. There is a ribbon cable connecting the front panel circuit board with the motherboard. Problems with mode switching, volume changes and dark display can sometimes be resolved by reseating this ...
Using a GDC SX/SR Server with 7.1 audio with a QSC/USL JSD-60D
It is possible to use a GDC server with an USL JSD-60D processor and get 7.1 audio and HI/VI output. It does require a bit of technical sleight of hand to make it work properly. The issue is that the JSD-60D is an 8 channel audio processor. It can be ...
Darco/Odyssey Products Model ODY-D2A-R2 Analog to Digital Audio Converter
Introduction: This Digital-To-Analog Audio Converter is designed for either home or professional audio applications. It converts Coaxial or Toslink digital audio signals to analog Left/Right audio, available via standard RCA jacks. The input supports ...
USL JSD-60 User's Manual
This link will take you to the current USL JSD-60 User's Manual USL JSD-60 User's Manual