[TenTec] triton 540 reversed polarity

[Carl Moreschi]

Don't overlook the possibility that the Trition was protected from reverse
polarity by a reverse diode across the 12 volt supply connection.  If this
is the case, the diode would most likely now be shorted and that is al that
is wrong.

Carl Moreschi N4PY
121 Little Bell Drive
Bell Mountain
Hays, NC 28635
----- Original Message ----- 
From: "Louis A. Ciotti Jr." <lciotti at twcny.rr.com>
To: <geraldj at storm.weather.net>
Cc: <tentec at contesting.com>
Sent: Tuesday, August 07, 2007 12:36 PM
Subject: Re: [TenTec] triton 540 reversed polarity


> Thanks for the information.  I have located the manual which has a
schematic.  I guess I am going to have to dig in and start changing parts.
>
> I do not think I destroyed every IC as the radio powers up and the remote
digital readout I have for it works and shows the correct frequency so some
portion of it is working.  That and the fact that I can still hear static if
I turn the volume up to max means that some portion of the receiver is
working.
>
> Thanks again, and keep the ideas comming.
>
> 73
> Lou
> KC2RVD
>
>
> -----Original Message-----
> From: "Dr. Gerald N. Johnson" <geraldj at storm.weather.net>
> Date: Tuesday, Aug 7, 2007 12:21 pm
> Subject: Re: [TenTec] triton 540 reversed polarity
> To: tentec at contesting.com
>
> On Mon, 2007-08-06 at 21:24 -0500, Stuart Rohre wrote:
> > Reversal of DC polarity may have failed some electrolytic capacitors.
Also,
> > if it is working weakly, maybe a diode in a bridge rectifier is open.
How
> > long was the polarity reversed?  That may tell if any active devices bit
the
> > dust.
> >
> > -Stuart
> > K5KVH
> >
> >My experiences with reversed polarity is that the fuses are reliable
> >indicators of fried semiconductors. That semiconductors fail faster than
fuses open, so time isn't much of a factor.
> >
> >ICs dislike reversed polarity and often short. Some ICs running off
internally (to the radio) regulated voltages may be protected by the
> >regulators, some regulators may feed full supply under reversed polarity
conditions. Small bipolar transistors base-emitter junctions often
> >(especially RF types) have lower break down voltages than the inverted
supply and the avalanche can do serious junction damage.
> >
> >Expect to test and maybe have to replace every IC and every transistor
along with many electrolytic capacitors. And the miniature electrolytics may
have been poor anyway just from age.
> >
> >-- 
> >73, Jerry, K0CQ,
> >All content copyright Dr. Gerald N. Johnson, electrical engineer
> >
> >_______________________________________________
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> >TenTec at contesting.com
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> >
>
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