[450] IC-207H repair

[K1FSY]

google translate did good for me i got all that out of it when i read
through it the first time. My cracks were in pretty much exactly the
same place as his too.

I was going to try using shield wires cause i have a mess of them handy
but i said screw it and just added and reflowed the solder.

On 10/27/2015 7:21 PM, John Foege wrote:
> And because Google translate is garbage, I will translate this line,
> because it's the key line:
> 
> Vermutlich durch unterschiedliche Ausdehnungskoeffizienten zwischen
> Keramik und Kühlkörper treten im Keramiksubstrat feine Risse auf, die
> mit dem Auge nur mühsam zu erkennen sind. Irgendwann führt das dann auch
> zu Unterbrechungen in den aufgedruckten Leiterbahnen, bei mir gleich an
> sechs verschiedenen Stellen.
> 
> Presumably, fine cracks occur, which are only with great effort visible
> to the naked eye, due to the different thermal coefficient of expansion
> between ceramic and heatsink material. With time, this leads to cracking
> in the printed circuit board traces as well, which in my case, was
> present at six different places.
> 
> On Tue, Oct 27, 2015 at 7:14 PM, John Foege <john.foege at gmail.com
> <mailto:john.foege at gmail.com>> wrote:
> 
>     Vermutlich durch unterschiedliche Ausdehnungskoeffizienten zwischen
>     Keramik und Kühlkörper treten im Keramiksubstrat feine Risse auf,
>     die mit dem Auge nur mühsam zu erkennen sind. Irgendwann führt das
>     dann auch zu Unterbrechungen in den aufgedruckten Leiterbahnen, bei
>     mir gleich an sechs verschiedenen Stellen.
> 
>     This is, indeed, exactly what I had guessed the problem to be when
>     talking it over with Bill while you were off the air earlier. I told
>     Bill, that in my opinion, most likely it was the repeated thermal
>     cycling of heating and cooling that lead to cracks in traces on the
>     power module. Looks like I was right !! Really a very common mode of
>     failure. If you were a long-keyer, which you are not, I would have
>     said de-soldered itself. But knowing that you don't key long, I
>     figured cracked traces from thermal cycling.
> 
>     On Tue, Oct 27, 2015 at 6:57 PM, K1FSY <k1fsy at vhfwiki.com
>     <mailto:k1fsy at vhfwiki.com>> wrote:
> 
>         I was having intermittent power output problems with the IC-207H I
>         received in trade from K1MAL. Noticed 35w power output on 2
>         meters which
>         was reduced and then no output. After opening it up and
>         desoldering the
>         antenna connector to get the board out I did some
>         troubleshooting in the
>         APC circuit because the internet said it was a common fail point,
>         however it shares the same APC circuit for both vhf and uhf and
>         the 70cm
>         side worked fine. Desoldered the PA module and popped off the
>         plastic
>         cover as per this page that john will appreciate, and sure
>         enough the
>         thing had microfractures in the ceramic board. Instead of going
>         crazy
>         with tiny wires I just added a little solder and reflowed the traces
>         that the cracks were running under and buttoned it back up.
>         Apparently
>         Icom didn't bother putting heatsink compound on the bottom of the
>         modules and just screwed them to the board, so eventually they
>         heat up
>         too much and snap crackle pop.
> 
>         http://www.dk7in.de/TM733.html
> 
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> 
> 
> 
> 
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