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lincoln audio fault

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Old 05-02-2010, 08:59 AM
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Default lincoln audio fault


I have had a fault with my lincoln for some time now, maybe since I bought it in that the audio seems a bit garbled so its hard to hear weak signals. It is most noticeable on am as the unimposing audio makes it difficult to understand even strong signals.

I have some trouble with tinittus and find it hard to copy low frequency sound so audio quality is very important to me.

Attached is a nokia phone recording of how it sounds in USB mode. The first twenty seconds are squelched. It gets quite loud sometimes although I did not catch it in the recording.I am reluctant to spend much money repairing the radio as I recieved the radio with security stickers which would lead me to believe that even they did not know where the fault lay.

Sorry about the obscure format but it was all I could do. I attempted to convert it to a wav file with a program I got here MIKSOFT - more than ideas. but vista is buggy and won't let it work with the program giving a path name error.
I had a similar problem with a pentazip program.

I will probably trade this in locally and buy a 2970dx if no-one has any ideas. Even if I couldn't repair it myself at least if someone gave pointers to some chip or capacitor I could say something to the repairman.

The recording is quite noisy with 230v ac line noise which is not the radio's problem. I manipulated the volume control in the latter part of the recording and I also used computer speakers to bring up the squelched volume.

The only thing the audio reminds me of is when I used a secondhand linear and something in the unit made the radio recieve sound garbled in the same way(possibly corroded contact's in the linears relay) but that would not apply here because as far as I know the lincoln does not use relays.

So here goes. I'll leave this post here a few weeks anyway. I have other radios so I am not fully unyoked.


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Old 05-02-2010, 09:08 AM
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attachment here
rename the file to lincoln.amr if you want to play it. my nokia is a 3120.

Last edited by fodendaf; 02-14-2012 at 02:12 PM.

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Old 05-02-2010, 04:00 PM
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Hi let Rogerbird chime in on the he is the expert on these radios btw far better than a rci or go to rodgerbirds site

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Old 05-02-2010, 05:10 PM
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Rogerbird's Radio Modification Information Page

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Old 05-03-2010, 05:41 AM
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his site only has mods though, and some alignment info I think not what I wanted.

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Old 05-11-2010, 12:22 AM
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Default Rx

Hello,
It could be a bad audio IC, but probably bad caps.

I would suggest a couple of Capacitor replacements.

Typical failure in the audio circuit.

Replace C95 and C97. They are 470uf 10v and 47uf 10v.
Use 16 or 25 volt replacements.

Also you may want to replace Q1, I have seen a few of them 'go weak' and RX improves greatly after replacing, with the same value part.
2SC1674

For a board layout, CBTricks has the best one.. (its a 2510, but the same as a Lincoln)
http://www.cbtricks.com/radios/unide...b_main_pcb.gif

Email me if you have any questions..

Rogerbird1 @ aim . com
(remove the spaces)

Roger

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Old 05-11-2010, 09:31 AM
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thanks rogerbird. I installed a 25v47ufcap and 16v470uf cap from old circuitry I had handy but with no noticeable improvement.

It probably wouldn't be too expensive to recap the whole radio which I might do next as I have a kenwood ts850 that I should do the same with as its on it's last legs and order all the parts at once.

I wonder though is the 2sc2999 a replacement for that part you mentioned as it would be handy to order a few extra to boost the recieve. I think it was the original part in the first IF amp in the ss3900 but my memory could be playing tricks.

Update: Problem Fixed
Once the 2 new caps warmed up they were fine, no ragged noise even when the radio is squelched . Thanks. I can hear people I wouldn't have had a hope with before. Anyone ever call you a genius before?

Last edited by fodendaf; 05-11-2010 at 03:32 PM.

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