[ICOM] Mic problem on IC-756-ProIII

[George Waschka]

I don’t know about the 756 series but one of my other Icoms had a low value resistor in line, I suspect as a fuse. It was blown, perhaps due to some accessory that shorted the pin to ground. 

Al, K5TAN

Sent from my iPhone

> On Jun 26, 2019, at 12:09 PM, Ken Winterling <wa2lbi at gmail.com> wrote:
> 
> Jim,
> 
> There may be a loss of the DC voltage that coexists with mic audio on Pin 1
> of the mic jack.  Check that Pin 1 of the mic jack has approximately +8VDC.
> as measured to Pin 7.  The Icom electret mics require that voltage for
> operation.  The Heil mics, I believe, are dynamic and do not use the
> voltage. They have a DC blocking cap.
> 
> Ken
> WA2LBI
> 
> 
> 
> 
> 
>> On Wed, Jun 26, 2019 at 11:35 AM JimR <KD1YV at oneyv.org> wrote:
>> 
>> After being in non-climate-controlled winter storage and a 500 mile
>> move, I put my 756-III in service.  I tried the stock mic, an HM-36, but
>> have no RF power, and no indication on the ALC meter. I swap in my Heil
>> pro headset, and the mic in that works fine.
>> 
>> So I figure my HM-36 did not survive the cold.  I call HRO to order a
>> replacement, but they tell me it is discontinued, and offer me an HM-219
>> which I buy.  I plug that in, but it has the exact same symptoms.  No
>> RF, no ALC.  Again the Heil headset mic works fine.
>> 
>> As an aside, I plug in my SM-30 mic, and it has the same symptoms, but
>> it has been a bit flaky for a long time, so I can't say that is a valid
>> test.
>> 
>> Has anybody already solved this problem?  Thanks!
>> 
>> --
>> 73 de Jim, KD1YV
>> 
>> -
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> To support QSL/QTH.net: http://www.qsl.net/donate.html