[ICOM] 756 pro III noise

[Jim Hargrave]

I would also suggest you remove and re-seat each connector inside the radio.
There could be a corroded or high impedance connection.

     73's Jim
      W5IFP

> -----Original Message-----
> From: icom-bounces at mailman.qth.net
> [mailto:icom-bounces at mailman.qth.net]On Behalf Of Alex
> Sent: Thursday, October 14, 2010 10:39 AM
> To: 'ICOM Reflector'
> Subject: Re: [ICOM] 756 pro III noise
>
>
> I have never opened up my ProIII, but if it's anything like the
> FT-897, you
> may have a loose board that is not well grounded. I found on the FT-897 a
> long time ago that the radio would break out in oscillation on 6 meters
> because the main board was not grounded well. Tightening all the screws so
> that the board is firmly connected to the chassis did the trick.
> The FT-897
> I have had all screws a quarter turn too loose, consistently on
> all boards,
> when it left the factory. Maybe you have a similar issue. You
> could check to
> make sure that all screws are tight.
>
> 73,
> --Alex KR1ST
> http://www.kr1st.com
> http://www.airlinkexpress.org
>
> -----Original Message-----
> From: icom-bounces at mailman.qth.net
> [mailto:icom-bounces at mailman.qth.net] On
> Behalf Of Jaime Gomez
> Sent: Thursday, October 14, 2010 11:10 AM
> To: ICOM Reflector
> Subject: Re: [ICOM] 756 pro III noise
>
> Thanks to all who have answered my request for help. I opened the
> radio and
> so far what I have found is that if I disconnect the cable at J211 in the
> main board, which carries the signal from 3LO the noise
> dissapears. It looks
> like something in the VCO card is causing the noise.
> Any other hints?
> Thank you,
>
> Jim, HK1N
>
> On Wed, Oct 13, 2010 at 2:47 PM, Alex <alex at kr1st.com> wrote:
>
> > Hi Jim,
> >
> > This sounds suspiciously like some cable became disconnected from a PCB,
> > and
> > is perhaps now close to the CPU board or even touching it. Possibly a
> cable
> > that connects to the PA board. Very wild guess without looking at the
> > transceiver. :)
> >
> > I don't have any experience with this, but I found a similar
> problem with
> a
> > FT-897. The problem was that I could hear a noise on 70cm every time I
> > turned the dial. What I ended up doing was rerouting the small
> coax cable
> > that came from the RX/TX board and connected to the PA board
> away from the
> > front panel. The noise was then substantially less.
> >
> > So it may not be something terribly complicated what is wrong with your
> > radio.
> >
> > I hope this helps somewhat.
> >
> > 73,
> > --Alex KR1ST
> > http://www.kr1st.com
> > http://www.airlinkexpress.org
> >
> >
> > -----Original Message-----
> > From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
> > On
> > Behalf Of Jaime Gomez
> > Sent: Wednesday, October 13, 2010 2:36 PM
> > To: ICOM Reflector
> > Subject: Re: [ICOM] 756 pro III noise
> >
> > Well, I did the reset, as per Walt's instructions. Same thing, no Tx,
> > popping noise on all frequencies, not affected by the noise
> blanker, AGC,
> > filters, etc....and now I noticed something else, when I turn the dial,
> the
> > popping increases and depends of the dial turning speed....Obviously the
> > auto tuner is not working because there is no rf to excite it....
> >
> > What can I look at, if there is anything?
> >
> > 73, Jim, HK1N
> >
> > On Wed, Oct 13, 2010 at 12:36 PM, Walt Heilsnis - WB2VSJ <
> > wb2vsj at earthlink.net> wrote:
> >
> > > This is beginning to sound a little bit familiar - I vaguely remember
> > > something somewhere about a transmit issue like this and I
> think it was
> > > Auto-Tuner related.
> > >
> > > Anyway, according to the PRO III Manual the reset procedure is:
> > >
> > > - Make sure the transceiver power is OFF.
> > > - While pushing [M-CL] and [(F-INP)ENT], push
> > > [POWER] to turn power ON.
> > > - The internal CPU is reset.
> > > - A/D convertor calibration of the DSP unit starts and it
> > > takes 10 sec.
> > > - The transceiver displays its initial VFO frequencies when
> > > resetting is complete.
> > > - Correct the set mode settings after resetting, if desired.
> > >
> > > I have a PRO II and have not had any issues like this (yet) :)
> > >
> > > Walt
> > >
> > >
> > > -----Original Message-----
> > > >From: Jaime Gomez <cwdx.hk1n at gmail.com>
> > > >Sent: Oct 13, 2010 1:07 PM
> > > >To: ICOM Reflector <icom at mailman.qth.net>
> > > >Subject: Re: [ICOM] 756 pro III noise
> > > >
> > > >Hi Walt, I have connected a dummy load to the antenna terminal, no
> > change,
> > > >noise is present in all bands, all modes, not affected by attenuators
> or
> > > >preamps, all other radios in the station (7800, proII, proIII, 781)
> work
> > > >fine. I just noticed also that it is not transmitting, the
> Tx red light
> > > just
> > > >blinks and turns off and no power output.
> > > >
> > > >How do I hard reset the rig to factory fresh as Rich sugested?
> > > >
> > > >Thanks, 73
> > > >
> > >
> > > ----
> > > Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> > > Icom Users Net: Sundays, 1700Z, 14.316 MHz
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> > >
> >
> >
> >
> > --
> > Jim, HK1N
> > ----
> > 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
> >
> > ----
> > 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/
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> >
>
>
>
> --
> Jim, HK1N
> ----
> 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
>
> ----
> 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