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
> 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.
> -----Original Message-----
> From: "Dr. Gerald N. Johnson" <firstname.lastname@example.org>
> Date: Tuesday, Aug 7, 2007 12:21 pm
> Subject: Re: [TenTec] triton 540 reversed polarity
> To: email@example.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
>> 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
>> TenTec mailing list
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