[450] IC-207H repair

[John Foege]

Yes. Google will give you the gist, but it fails at a nuanced translation.
Therefore, I decided I'd give a better translation for the key line !! For
ARCHIVAL PURPOSES...you know?

:-)

On Tue, Oct 27, 2015 at 7:24 PM, John Foege <john.foege at gmail.com> 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> 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>> 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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>> >         450 at lists.vhfwiki.com <mailto:450 at lists.vhfwiki.com>
>> >         http://lists.vhfwiki.com/cgi-bin/mailman/listinfo/450
>> >
>> >
>> >
>> >
>> >
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>> >
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