[Boatanchors] SX-28 Help Needed

[GBrown]

I have rewound Audio trannys for the SX-28, SX-42, etc. Just $75.00 plus
shipping.
Regards,
Gary...WZ1M
----- Original Message ----- 
From: "Drew Papanek" <drewmaster813 at hotmail.com>
To: <boatanchors at mailman.qth.net>
Sent: Thursday, February 23, 2006 12:11 PM
Subject: [Boatanchors] SX-28 Help Needed


>
> Joe Connor  wrote:
>
> >I replaced all the electrolytics and paper caps in my SX-28 several
> >months ago. It ran great until tonight, when smoke started coming from
> >the audio-output transformer. I need some help in diagnosing and
> >repairing the problem:
>
> >1.  The only original cap I see near the trouble area is a 2,000 pfd mica
> >cap (C-76) across the primary of the audio transformer. Is that a likely
> >suspect? If so, I'll replace it. Is a .002 mfd orange drop a suitable
> >replacement?
>
> An Orange Drop would work fine here.  Just make sure that it has a high
> enough voltage rating (1200V or more).  Failure of that cap is not likely
to
> kill the output transformer, however.
>
> >2.  Any other likely suspects (other than a shorted audio transformer)?
> >The weird thing is that this set still plays great even when the smoke
> >starts. (I kept it one only long enough to pinpoint the precise source of
> >the smoke).
>
> Seems odd.  Perhaps one of the output tubes (6V6) has shorted.  If that
were
> the case I would expect the common cathode resistor for the 6V6's (220
ohms,
> 2 watts) to be somewhat cooked also.
>
> >3. If I need to replace the audio transformer, what would be a suitable
> >replacement from AES or Radio Daze? I'm currently running the set through
> >a PM-23 speaker. I'd like to keep using that speaker (if possible).
> >However, the 5,000-ohm impedance may be a problem. I suppose with a new
> >audio transformer I could always disconnect the matching transformer
> >inside the PM-23 to make the speaker 8 ohms. Any thoughts or suggestions?
>
> Peter Dahl makes an output transformer for the SX-28.  It ain't cheap, but
> is good quality and an exact replacement and will enable you to keep on
> using the PM-23 with no modifications.
>
> Drew
>
>
> _______________________________________________
> Boatanchors mailing list
> Boatanchors at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/boatanchors
> ** List Administrator - Duane Fischer, W8DBF/W9WZE **
> ** For Assistance: dfischer at usol.com **
> $$ For vintage radio info, see the HCI web site $$
> http://www.w9wze.org
>
>