CD Controller / FM Modulator Repair [was: CD Player]

Steve Scalmanini sscalmanini at
Fri Jul 15 08:27:08 EDT 2005

I've wayyy late posting this to the list but your "FM Modulator" aka "CD Changer Controller" 
is repairable.  I did it...almost...a year or so ago.  

The problem is most likely with the electro-mechanical RF relay that is supposed to change the 
input from the antenna (rear, I think) to the CD changer/modulator circuit when power is applied.  
It wears or weakens or gets dirty with age or whatever, and eventually starts adding static to the 
CD circuit until all you get is static.  It acts like the contact force gets weaker over time until it's 
too little to pass the signal.  

The solution is to replace the relay, a job NOT for the soldering challenged.  (Yes, I learned from 
experience.)  I don't recall the ID of the old relay (I wrote it somewhere but it's not important) 
but the correct replacement part from Digikey is P/N 255-1572-ND, "Relay 2.6GHZ 500MA 
12VDC PCB".  

But you don't need to know that either...because if you have access to a temperature-controlled 
soldering iron...and to good desoldering tools...and copper braiding...and a wad of resin flux...and 
experience at small-scale electronics work, and a few hours to try this on your own, and patience 
to last those few hours, and you're not on the no-fly list, then I'll send you one of the three in my 
hand at this moment and you can try to be the first on this list to SUCCESSFULLY repair one of 
these modules.  And if you're reeeally nice and don't have a wad of flux then I might send you 
a scoop in a ziplock along with the relay, because you're going to need it.  (It was way harder to 
find than I expected.  Local RS's were out of stock for months.)  

My attempt at repair turned into a lessen in what's not good enough solder equipment and technique.  
Little did I know the value of copious flux to clear tiny holes in PC boards of solder ... withOUT 
lifting the trace, silly.  After I damaged my PC board I just searched for a used module in the 
marketplace and it's played fine since.  Then I found another and got an extra for the future.  

So, first come, first served, but you have to promise that you KNOW what you're doing with fine 
soldering.  I thought I knew...ha!  NOT.  Contact me offline.  The clock starts ... NOW.  

Steve Scalmanini 
Ukiah, CA 



This is what I love about these cars...they all have the same problems!  I'm 
going with Phil on his diagnoses of the modulator being bad.  I have the 
same problem on my car and have all but given up on the CD player.  
Sometimes you can eek a little more time out of the system by changing the 
modulator "broadcast" frequency (ie 88.3 to 88.7 I think?), but eventually 
the whole thing just goes t.u.

I'm wondering if there is a replacement unit that can be put in there 
instead of the factory ones.  It would seem that this is a universal part 
with the only problems being make sure the connectors mate up.  I thought 
you used to be able to get universals like that from Cruthfield, but it's 
been a long time since I was a high school kid mesmerized by stereo gear.


How do the wire runs work to and from the modulator?  Obviously one side 
attaches to the antenae input on the head unit, but does the other side run 
all the way back to the CD player?  If not, are the inputs on the modulator 
RCA plugs?

Derek P

...snip... 2. When I attempt to listen to a CD, it will begin to play for anywhere
from 5-30 seconds before the music is replaced by static. Just had my
radio head unit overhauled by Brett Seamens (thanks to a lister's
suggestion), but apparently that wasn't my problem. Does anyone
recognize this symptom?

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