[R-390] Low Audio

[JMILLER1706 at cfl.rr.com]

Sometimes WD-40 or Deoxit and high-impedance tube circuits don't mix 
well.  If sockets or wafers are soaked with the chemicals and absorb 
them, they might form enough of a path to ground to degrade operation 
until the stuff evaporates.  

----- Original Message -----
From: ToddRoberts2001 at aol.com
Date: Monday, December 12, 2005 0:53 am
Subject: Re: [R-390] Low Audio

> In a message dated 12/12/2005 12:45:30 AM Eastern Standard Time, 
> fwbray at mminternet.com writes:
> I am a new R-390A owner and am encountering a problem.
> 
> Over the weekend, I pulled the front panel so that I could align a 
> couple cams and clean the pots and switches on the front panel 
> with 
> Deoxit.  I also pulled the power supply and audio deck to do basic 
> chassis cleaning with a paint brush and WD-40 on a cloth.  Upon 
> reassembling the radio, I found it has very low audio, with some 
> distortion when I crank up the local audio gain.  However, 
> everything 
> else seems to be working normally.  I have swapped the audio deck 
> tubes 
> with known good ones, just in case, but this made no difference.  
> It was 
> working before I started, but clearly needed to have the pots and 
> switches cleaned.
> Is there anything obvious I might be overlooking?
> Thanks.
> 73,
> Fred
> KE6CD
> 
> Try turning on the limiter and see if the audio sounds better or 
> louder. If 
> this is the case there may be some bad caps around the limiter 
> tube V507. The 
> ones that usually cause trouble are  C532 and C537. Also check 
> limiter tube 
> V507. 73 Todd WD4NGG
> _____________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>