[Premium-Rx] JRC Repair?

[w3jn at verizon.net]

Unfortunately the manual doesn't cover synthesizer alignment.

Many times when this happens the VCO components have drifted far enough out of tolerance that the synth won't lock.  The way to fix this is to set the receiver frequency at some specified point, monitor the input voltage to the VCO, and adjust the coil or trimmer cap in the VCO for a specified VCO voltage.  Unfortunately JRC wasn't kind enough to provide that info.

You could try giving L28 on the synth board a quarter-turn tweak in each direction and see if the VCO locks.  If the VCO is in fact locked and the phase detector just thinks its unlocked, then IC35 is probably bad.  You can tell for sure by looking at the phase detector output with a scope.

Good luck!


Jan 4, 2010 10:42:16 PM, Ka9p at aol.com wrote:

Happy New Year.
 
I've got a NRD-515 that apparently has a synthesizer issue, as the internal 
 CD16 LED is lit, indicating a problem with one of three main board  
synthesizer loops.
 
I've snooped around a bit and the correct signals seem to be there, but for 
 some reason the radio thinks not, and sends itself into mute.
 
Can anyone recommend someone that works on these receivers?  I've  talked 
to JRC, Sherwood and Universal, with no joy.
 
Thanks, Scott
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