[R-390] Crystal resurrection

[Gordon Hayward]

Indeed - crystals are tougher units than we think. The clip on the
left of the picture looks a touch corroded. The clips that I use on
high temperature crystals (running at 200 degrees C) are attached
with a silver/polyimide cement (just a dab). I wonder if a dab of
silver epoxy cement might work too.  The only problem is that if it
doesn't, getting it off the connection flag deposited onto the
crystal will probably take the flag right off the crystal.

Cheers, Gord, VE3EOS.

----- Original Message -----
From: "rbethman" <rbethman at comcast.net>
To: r-390 at mailman.qth.net
Sent: Wednesday, March 19, 2014 1:45:58 PM
Subject: Re: [R-390] Crystal resurrection

Mark,

Great idea and work!

These old girls really can take a beating, yet they come back to life.

Your comment: "This R-390A radio is one tough unit!" has never been truer!

Effort, patience, and going the extra mile gives surprising results!

Keep going.  It is worth all the effort and work.  Eventually one gets 
what they desire.

Regards,
Bob - N0DGN



On 3/19/2014 1:32 PM, Mark Richards wrote:
> As I work through some issues with my R-390A crystal oscillator, two 
> crystals were identified as non-functioning: Y402, 10.5MHz and Y413, 
> 9.5MHz.  Considering the cost of replacing these at the only supplier 
> I could find, Fair Radio, I figured that a repair try which saves me 
> $14 each is worth the gamble.
>
> After some digging, I found a fellow traveler:
>
>     http://home.earthlink.net/~chestnutl/Helptipspage3.html
>
> The author found in one instance the internal crystal structure was 
> touching the cover which prevented oscillation and, in another 
> crystal, that re-soldering was needed.
>
> Rather than use a torch, I set my soldering iron to around 800 degrees 
> F and after a minute or so managed to carefully wiggle up the cover.
>
> In both crystals there was no obvious alignment problem, so I set 
> about to renew the soldering.  But, before that, I cleaned each 
> crystal using isopropyl alcohol applied carefully with a cotton ball.  
> Then, with the soldering iron, touched up each lead, first at the very 
> base where it attaches to the pin, and then carefully moved up to the 
> crystal element, adding a bit of solder.  This was done at around 650 
> Degrees F.
>
> Tacking the cover back to allow for re-insertion we have success: each 
> crystal came to life!
>
> Perhaps this is non-preservation-quality, but 30 minutes of careful 
> effort just saved me $28 I didn't have to throw.
>
> This R-390A radio is one tough unit!
>
> /K1MGY
>
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