[Heath] SB-104A VOX locks up

[JF]

On 3/21/2016 11:53 AM, Alexander N. Gerli wrote:
> Hi, folks!  Strange symptom this morning. The VOX is locking 
> up, that is it won't release even if the Delay and AntiVOX are set 
> minimum. Sensitivity is set just enough to trigger. Have to push 
> the VOX button off to release it. PTT is normal.Was working 
> correctly past few days.
> Anyone else have this symptom? The ICOD notes for the Transmit 
> Audio Board aren't any help.
> 73,  Sandy AC1Y

Haven't heard of it before, could be a bunch of things, from 
corroded/loose connectors to deteriorated components. Check to find 
if it does this with the mic disconnected, and with a different mic. 
If no change then I would first suspect the TX Audio/Regulator board 
(board B). I don't recall if the ICs are socket mounted, but if they 
are you could try re-seating them and/or substitution. Also try 
re-seating all the boards, and verify the voltages on the various 
power buses to board B.

If that doesn't help disconnect the RF from the drivers, put board B 
on an extender board and verify its inputs from the various jacks and 
controls:  mic jack, anti-vox, PTT/VOX button (being mechanical, it 
is to be especially suspected), vox delay, patch in, key jack, vox 
gain, mic gain, +RX line, all while monitoring the +TX and T/R relay 
outputs.

73
John   KE5ZB