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RE: [alfa] Re: gtwe6 weird elec'l, continued



Hi Glenn:

There are two distinct noises that you might be hearing. The alternator whine is fairly high pitched and smooth-sounding. It generally won't destroy AM or FM reception, and is usually more in the background than the other type of noise. That other noise is from the ignition, and if you listen carefully, you'll be able to hear each spark plug firing. It's a rougher noise than alternator whine, and it will definitely wreck AM reception. Both noises vary with engine rpm, and increase in frequency as the rpm's rise. Alternator noise can often be tackled with a capacitor, or combination of a capacitor and coil, often fitted directly to the power lead(s) of the radio/amplifier(s). Spark plug noise is actually being transmitted as a radio signal, and is tough to beat in a fiberglass-bodied car. Since you mentioned no problems with FM reception, I'll bet ignition noise is all you've got. Older Corvettes actually had chromed-steel channels that the plug wires were routed through, while later versions had a braided steel shield on each wire, that was grounded to the engine block. I'm not sure what they're doing on the latest version, but I think the coils are now mounted directly on the spark plugs, and are shielded by the head and valve cover. I had a Lotus Europa JPS many years ago, with a foil shield on the underside of the rear deck lid, and quickly learned to use the radio only when the car was parked. I also had a Saab Sonnett that had a grounded wire mesh imbedded into the underside of the hood, and that didn't work very well, either. Perhaps modern suppression ignition wires and resistor plugs may work better than what I had ~20+ years ago.

Regards,

Dean
Lutz, FL
'74 & '87 Spider Veloce's


At 02:25 PM 10/17/2003, you wrote:

Well that's interesting. I wonder if that info can also help me out.

My new non-Alfa (with initials that sound like "TVR") has the same
problem with AM reception my 164Q had - no AM reception when the engine
is running. When I shut it off, it's great. Of course that means no AM
radio while I'm driving, which is what I like to listen to.

On my 164, I never found out the culprit (but admittedly I had no clue
even what to look for). I was surprised to find a similar Sony radio in
my "new" car, and have the same problem. There's clearly some
interference from something in the car. I will have to look on my
alternator for one of these devices.

Interestingly, it doesn't affect FM reception, and didn't on the 164,
either. I thought it was likely there was a bad ground somewhere, which
I guess is still possible on the TVR (actually more likely, I guess,
since there are fewer places to hook a ground, with the tube frame) but
really it seems unlikely it's a ground problem.

I'll take a look at my car.



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
[email protected]
Sent: Friday, October 17, 2003 1:28 PM
To: "Dean W. Cains"; [email protected]
Subject: [alfa] Re: gtwe6 weird elec'l, continued

ah yes - this explains the whine i also hear, from the fusebox (or
speedo?) area.  no noise thru the speakers, cuz there's no radio in my
car!  ;~)

thanks,

doug s.

"Dean W. Cains" <[email protected]> wrote:

>Hi Doug:
>
>That's just a small capacitor, which shunts to ground any stray AC that

>might cause radio interference (a high-pitched whine, that varies with
>rpm).  If it's a problem, many car stereo install shops (or Radio
Shack)
>can set you up with a similar replacement part.  Both of my Spider's
have
>the same alternator as your GTV6, with out the capacitor, and I'm not
>hearing any interference.
>
>Regards,
>
>Dean
>
>At 08:53 AM 10/17/2003, you wrote:
>
>>Date: Thu, 16 Oct 2003 20:36:53 -0400
>>From: [email protected]
>>Subject: [alfa] gtwe6 weird elec'l, continued
>>
>>hi all,
>>
>>well, the adjustable woltage regulator showed up, but now after
removing
>>the old one, (turns out it, too, was an adjustable model), i'm not
sure it
>>was the culprit.  see, there's this other weird li'l elec'l device on
the
>>back of the alternator, that was broken.  it screws into the
alternator
>>w/one screw, about 90 degrees away from the woltage regulator, has a
wire
>>coming off of it that plugs into the alternator near the center.  the
li'l
>>bracket that holds it to the alternator, is snapped off - looks like
some
>>kinda rectangular mini-coil, which is held in a black plastic
>>case.  (seriously deteriorated.)
>>
>>i soldered the bracket back on to the coil, & covered the deteriorated

>>plastic w/marine goop, but i dunno if the repair will be successful,
as i
>>haven't put it all back on the alternator, since i need to get some
>>distilled hoh for the battery anyways...
>>
>>but, i'd really like to get another one of these elec'l parts - it's a

>>bosch part, has this on it:  2.2 (w/some unidentified ting after the
2.2 -
>>uf?), f/100v.  part # is: 0290 800 036
>>
>>thanks again,
>>
>>doug s.
>
>
>

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