Why not try to troubleshoot it rather than randomly changing parts?
Do you have a signal source for audio and a tunable one for RF?
Start injecting an AF signal at the speaker audio amp and work
backwards down the change towards the antenna. Switch to an IF
injected signal at the product detector (and any other mixers). Then
RF when you get past the first mixer (try each band).
You find which sections don't work when he signal disappears then you
can figure what is broken in each section.
On Aug 7, 2007, at 9:36 AM, Louis A. Ciotti Jr. wrote:
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@storm.weather.net>
Date: Tuesday, Aug 7, 2007 12:21 pm
Subject: Re: [TenTec] triton 540 reversed polarity
To: tentec@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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73 DE N7WIM / G8UDP
Kevin Purcell
kevinpurcell@pobox.com
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