[450] IC-207H repair

[K1FSY]

I also put some ARCTIC ALUMINUM V on the back of the modules when I put
them back down, there did not appear to be anything previously on the
module, it was very clean.

On 10/27/2015 7:24 PM, John Foege wrote:
> Solder is a better idea...it's going to handle the current better and
> also not be overly inductive.
> 
> On Tue, Oct 27, 2015 at 7:22 PM, K1FSY <k1fsy at vhfwiki.com
> <mailto:k1fsy at vhfwiki.com>> wrote:
> 
>     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>
>     > <mailto: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>
>     >     <mailto: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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