Serial mode and external speaker 536HP

[AA6IO]

Hope this was not asked somewhere else. If so, I missed it.
Just got ARC536 beta ver 0.80 working. Seems to be working very well. USB serial driver is working fine as provided by Butel. Noticed a problem with USB serial mode when tried virtual control. But found out it has nothing to due with Butel software.
When I plug in USB cable and press serial mode, the line-in to my computer from my external speaker output drops by about 50% or more and is muffled. (Use this because earphone output seems low to me). However, this is only when I have external speaker output plugged into line-in in back of computer. With an actual external speaker, there seems to be no problem or audio loss. But I watch my line-in on my Dell, and the minute I hit USB serial, the audio input drops like crazy.
Anyone else experience this when they are in USB serial mode and using line-in to computer? Is this some kind of a grounding issue? Is there audio coming out of the USB serial mode that I am unaware of?
Thank you.

Steve AA6IO

 

[an39511]

This problem is well discussed in other threads. The problem is the rear audio is a BTL output. When you connect your patch cable from the rear of the 536 to your computer, and then plug your USB cable it, you are causing a ground fault that is shorting the audio out, hence the low audio. Recommend you disconnect your audio cable (to prevent damage to your radio) and read the many other threads. There are solutions to your situation.

 

[AA6IO]

an39511
OK, thank you. Will search other threads more carefully. And will remove patch cable immediately.
Steve AA6IO