[net.micro.amiga] Noise in left audio channel

droid@well.UUCP (Marty Brenneis) (06/17/86)

Has anyone else noticed a noise like pseudostatic comming from the left
audio channel when using a modem (on an Amiga of course)?
I have my amiga hooked to a small stereo at my workstation and when I
am using the modem (Like now) I hear a static like noise that follows
the recieve light on the modem. I'm using Starterm for the terminal
emulation.

p.s. Will someone on the net cop to writing or knowing the where abouts
of the hackers that wrote it?

Love Long & Perspire
Marty the Droid
(well!droid) (pick a path, any path, this might be your lucky day!)

grr@cbmvax.cbm.UUCP (George Robbins) (06/17/86)

In article <1290@well.UUCP> droid@well.UUCP (Marty Brenneis) writes:
>Has anyone else noticed a noise like pseudostatic comming from the left
>audio channel when using a modem (on an Amiga of course)?
>I have my amiga hooked to a small stereo at my workstation and when I
>am using the modem (Like now) I hear a static like noise that follows
>the recieve light on the modem. I'm using Starterm for the terminal
>emulation.

There is an audio-in pin on the RS232 connector intended for use in phone
management stuff.  Make sure that your modem or modem cable is not attaching
an 'antenna' to this pin.

-- 
George Robbins - now working with,	uucp: {ihnp4|seismo|caip}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@seismo.css.GOV
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)

brent@well.UUCP (06/18/86)

One of the authors of StarTerm, Jim Nangano, is a Sysop on the AmigaForum on
CompuServe, if it's any help.

brent

rick@mips.UUCP (06/24/86)

I, too, experienced noise in one channel of my stereo when using a
modem.  I tried several things before finding out that the cables 
were indeed contributing to the problem.  Both serial and audio cables
were at fault.  The serial cable I use is a flat cable (25wires all laid out
in a flat fashion, NOT a shielded round cable) that had pins isolated at
the MODEM end.  This of course tends to make for a fairly good "antenna"
hanging out of the back of the amiga...  But more importantly, I had a
bad audio cable that had an open shield.  Add a fit of "neat-cable-fever"
where I taped all of the cables together one night while waiting for a
compile to finish, and you have a problem just waiting to jump and rear
it's ugly head.  (My machine exhibited the problem on the right channel..)
I probably compounded the effect by having my modem sitting on top of the
(unshielded) stereo cabinet as well.   During the debug phase of this "bug"
I took the case off of the Amiga and traced the circuitry back to the
drivers.  The circuit is terminated pretty well and I would not expect
your machine to be a cause of the problem.  First check for bad cables and
such.  Also be aware that taping the speaker cables to the telephone cord
(it's quite a ways to the phone jack sometimes) to make tings look
neater is not all that good of an idea either.  

--rick

-- 
--DISCLAIMER: All of the above is a personal opinion a result of imperfect--
--recall of facts (real or imagined) and in no way represents anyone else.--
UUCP:  {decvax,ucbvax,ihnp4}!decwrl!mips!rick         DDD: 408-720-1700 x278