[Kenwood] TM-2550 PLL problem

Tue, 26 Mar 2002 12:27:27 -0500

Clif,
You are either a genius, or have fixed a bunch of these (or probably both).
I unsoldered L10 on the ground side of the circuit board.  The original
solder connection was more of a "blob" on the board.  Once I scraped the
green coating from around the connection I was able to get a good
connection.

I had already resoldered several of the connections on the board that
weren't looking all that bad, and spent several hours with the scope and
freq counter - learned alot, but ultimately resoldering L10 fixed the
problem!
Thanks!

Steve
===========================
Steve Garwood, N�CZV / USAF MARS  AFA1GQ
Attica, Ohio
[email protected]

===========================
----- Original Message -----
From: Clif <[email protected]>
To: Steve Garwood <[email protected]>; <[email protected]>
Sent: Tuesday, March 26, 2002 11:48
Subject: Re: [Kenwood] TM-2550 PLL problem

> Resolder L10 in the RX VCO.
>
> Clif Holland, KA5IPF
> AVVid
> Authorized Kenwood and Icom Amateur Service
> www.avvid.com
> 1-800-214-5779
>
>
> ----- Original Message -----
> From: "Steve Garwood" <[email protected]>
> To: <[email protected]>
> Sent: Tuesday, March 26, 2002 10:31 AM
> Subject: [Kenwood] TM-2550 PLL problem
>
>
> > I'm having a problem with a TM-2550A - a PLL problem.
> >
> > When the PLL is unlocked, what checks can be done to locate the source
of
> > the problem?  The 10.24 Mhz oscillator is running, as is the 39.480 Mhz
> > oscillator.  It appears that the mix signal provided through IC-2 is
being
> > shut down by the unlock switches....  The test point associated with the
> RX
> > VCO set reads .02 vdc.  Adjustments have no effect.  It appears that the
> VCO
> > is being shut down by Q14 being biased on.
> >
> > Is there some way to defeat the "unlock" voltage for testing to narrow
> down
> > the search, and lastly, are there any common problems that crop up on
this
> > series of radios?
> >
> > Thanks for any advice?
> >
> > Steve
> > ===========================
> > Steve Garwood, N�CZV / USAF MARS  AFA1GQ
> > Attica, Ohio
> > [email protected]
> >
> >
> > ===========================
> >
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