[ICOM] ICOM HM-56 Mic. Stuck on Xmit

[Ken, WA2LBI]

Kent,

There have been numerous reports of that problem with the HM-56.  That 
mic has a microprocessor and keying transistor that is used to keep the 
mic keyed while you are pressing touch tone buttons.  I have heard of 
either/both the IC and/or the transistor going bad causing the keying 
circuit to remain engaged.  There have also been reports of bad caps 
that cause the same problem.

I have one here that is in the same condition.  I threw it in the 
"future repairs" box and used an older type out of the "junque box".  
The older one doesn't have a keying circuit; you have to hold the PTT 
button while dialing. If you are interested I can e-mail you a 
schematic of the mic.  It appears to be hand-drawn but it is better 
than nothing.

Ken, WA2LBI


Quoting KENT HUFFORD <khufford at comcast.net>:

>
> I have a HM-56 touch tone hand mic. I am trying to get working.
>
> When I turn on the radio, it goes into xmit.
>
> I've tried the CPU reset by holding the mw and mr buttons, then turning on
> the radio.
>
> That does not help.
>
> The mic. button is not pushed.
>
> Pushing all the buttons does NOT get the red light on the mic ever to
> illuminate.
>
> Ideas?
>
> Thanks,
> Kent
> KQ4KK
>