Propeller Demo board Rev F restarts anytime an Audio Plug is inserted into audi

soundman333

I have a rev f prop demo board that restarts anytime a 1/8 " TRS plug is inserted into the audio out jack. The same thing happens even when a "fresh" (no connections) plug is inserted. I originally thought that the jack had a "sense" lead and the behavior was normal. I took a look at the schematic which shows only the typical connections (left right and ground), but when examining the board, there are actually 4 pads soldered to the jack. (one maybe just an anchor?) Anyway, is this behavior normal and if so, why ?

If you insert the plug very quickly it occasionally won't restart, also the same results occur when "disconnecting" the plug.

Thanks,
Mark S.

rokicki

Sounds like something is shorting when that plug is inserted, killing your power supply. Scope the power supply when you
do the insertion.

soundman333

Oh Yes, that is my point, a TRS Jack (tip,ring,sleeve) does short during insertion but there should be no + - potential at that jack !

thanks,

Mark S.

Mike Green

You're right. There should be no +- potential at the audio output jack. There's not supposed to be any such potential, therefore you may have a defective board or defective headphone amplifier chip. I suggest you contact Parallax's support department when they open tomorrow and arrange for a replacement.