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Sick President Lincoln (no output)

S

ScooterCrunch

Guest
I have a newer Lincoln with MRF-455 final. It worked when I put it away a couple of years ago, but when I got it out again last year it won't transmit. Everything else seems to work ok except for the bargraph it's a little on the jumpy side, but does show relative numbers (I think it was doing this before I put it away). I found a bad driver transistor and replaced that. Still no output, but while diagnosing the rest of my problem the driver quit again. So back on the shelf until I have more time. I was thinking it was a capacitor shorted but now I'm not so sure. Is there a common problem here that anyone knows about? It's had the typical mods done to it, power, mic gain, freq, as well as an SP1A. I really want my radio back I miss SSB. If I can't figure it out soon I'll have to send it out.


</p>
 

I have a newer Lincoln with MRF-455 final. It worked when I put it away a couple of years ago, but when I got it out again last year it won't transmit. Everything else seems to work ok except for the bargraph it's a little on the jumpy side, but does show relative numbers (I think it was doing this before I put it away). I found a bad driver transistor and replaced that. Still no output, but while diagnosing the rest of my problem the driver quit again. So back on the shelf until I have more time. I was thinking it was a capacitor shorted but now I'm not so sure. Is there a common problem here that anyone knows about? It's had the typical mods done to it, power, mic gain, freq, as well as an SP1A. I really want my radio back I miss SSB. If I can't figure it out soon I'll have to send it out.


</p>
 
HI,

Puzzling,

If the driver was bad, and after replacing the new went bad,

I would check the Bias Diode. Possibly bad.

I would unsolder one leg of the Bias Diode and measure it with an OHM meter, it should read like a diode, between 500 and 1600 Ohms one way and open the other.



Also check the "Glue" used to secure the Coils and torroids, If it is BLACK and brittle it may be causing a problem. The "Glue" used should be tan or Yellowish not black or dark Brown, it must also be somewhat pliable not brittle. It has been known to be conductive and or Corrosive after it turns BLACK.



If its black it should be removed and the PCB and components need to be cleaned and inspected.



I have seen the legs of the Torroids and other coils turned green and eaten away from this.



I hope this helps,



Roger




</p>
 
HI,

Puzzling,

If the driver was bad, and after replacing the new went bad,

I would check the Bias Diode. Possibly bad.

I would unsolder one leg of the Bias Diode and measure it with an OHM meter, it should read like a diode, between 500 and 1600 Ohms one way and open the other.



Also check the "Glue" used to secure the Coils and torroids, If it is BLACK and brittle it may be causing a problem. The "Glue" used should be tan or Yellowish not black or dark Brown, it must also be somewhat pliable not brittle. It has been known to be conductive and or Corrosive after it turns BLACK.



If its black it should be removed and the PCB and components need to be cleaned and inspected.



I have seen the legs of the Torroids and other coils turned green and eaten away from this.



I hope this helps,



Roger




</p>
 

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