<div dir="ltr">Good...hopefully w/ some thermal grease it will not happen again !! Probably a manufacturing oversight.</div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Oct 27, 2015 at 7:25 PM, K1FSY <span dir="ltr"><<a href="mailto:k1fsy@vhfwiki.com" target="_blank">k1fsy@vhfwiki.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I also put some ARCTIC ALUMINUM V on the back of the modules when I put<br>
them back down, there did not appear to be anything previously on the<br>
module, it was very clean.<br>
<span class=""><br>
On 10/27/2015 7:24 PM, John Foege wrote:<br>
> Solder is a better idea...it's going to handle the current better and<br>
> also not be overly inductive.<br>
><br>
> On Tue, Oct 27, 2015 at 7:22 PM, K1FSY <<a href="mailto:k1fsy@vhfwiki.com">k1fsy@vhfwiki.com</a><br>
</span><span class="">> <mailto:<a href="mailto:k1fsy@vhfwiki.com">k1fsy@vhfwiki.com</a>>> wrote:<br>
><br>
> google translate did good for me i got all that out of it when i read<br>
> through it the first time. My cracks were in pretty much exactly the<br>
> same place as his too.<br>
><br>
> I was going to try using shield wires cause i have a mess of them handy<br>
> but i said screw it and just added and reflowed the solder.<br>
><br>
> On 10/27/2015 7:21 PM, John Foege wrote:<br>
> > And because Google translate is garbage, I will translate this line,<br>
> > because it's the key line:<br>
> ><br>
> > Vermutlich durch unterschiedliche Ausdehnungskoeffizienten zwischen<br>
> > Keramik und Kühlkörper treten im Keramiksubstrat feine Risse auf, die<br>
> > mit dem Auge nur mühsam zu erkennen sind. Irgendwann führt das dann auch<br>
> > zu Unterbrechungen in den aufgedruckten Leiterbahnen, bei mir gleich an<br>
> > sechs verschiedenen Stellen.<br>
> ><br>
> > Presumably, fine cracks occur, which are only with great effort visible<br>
> > to the naked eye, due to the different thermal coefficient of expansion<br>
> > between ceramic and heatsink material. With time, this leads to cracking<br>
> > in the printed circuit board traces as well, which in my case, was<br>
> > present at six different places.<br>
> ><br>
> > On Tue, Oct 27, 2015 at 7:14 PM, John Foege <<a href="mailto:john.foege@gmail.com">john.foege@gmail.com</a> <mailto:<a href="mailto:john.foege@gmail.com">john.foege@gmail.com</a>><br>
</span><span class="">> > <mailto:<a href="mailto:john.foege@gmail.com">john.foege@gmail.com</a> <mailto:<a href="mailto:john.foege@gmail.com">john.foege@gmail.com</a>>>> wrote:<br>
> ><br>
> > Vermutlich durch unterschiedliche Ausdehnungskoeffizienten zwischen<br>
> > Keramik und Kühlkörper treten im Keramiksubstrat feine Risse auf,<br>
> > die mit dem Auge nur mühsam zu erkennen sind. Irgendwann führt das<br>
> > dann auch zu Unterbrechungen in den aufgedruckten Leiterbahnen, bei<br>
> > mir gleich an sechs verschiedenen Stellen.<br>
> ><br>
> > This is, indeed, exactly what I had guessed the problem to be when<br>
> > talking it over with Bill while you were off the air earlier. I told<br>
> > Bill, that in my opinion, most likely it was the repeated thermal<br>
> > cycling of heating and cooling that lead to cracks in traces on the<br>
> > power module. Looks like I was right !! Really a very common mode of<br>
> > failure. If you were a long-keyer, which you are not, I would have<br>
> > said de-soldered itself. But knowing that you don't key long, I<br>
> > figured cracked traces from thermal cycling.<br>
> ><br>
> > On Tue, Oct 27, 2015 at 6:57 PM, K1FSY <<a href="mailto:k1fsy@vhfwiki.com">k1fsy@vhfwiki.com</a> <mailto:<a href="mailto:k1fsy@vhfwiki.com">k1fsy@vhfwiki.com</a>><br>
</span><div><div class="h5">> > <mailto:<a href="mailto:k1fsy@vhfwiki.com">k1fsy@vhfwiki.com</a> <mailto:<a href="mailto:k1fsy@vhfwiki.com">k1fsy@vhfwiki.com</a>>>> wrote:<br>
> ><br>
> > I was having intermittent power output problems with the<br>
> IC-207H I<br>
> > received in trade from K1MAL. Noticed 35w power output on 2<br>
> > meters which<br>
> > was reduced and then no output. After opening it up and<br>
> > desoldering the<br>
> > antenna connector to get the board out I did some<br>
> > troubleshooting in the<br>
> > APC circuit because the internet said it was a common fail<br>
> point,<br>
> > however it shares the same APC circuit for both vhf and<br>
> uhf and<br>
> > the 70cm<br>
> > side worked fine. Desoldered the PA module and popped off the<br>
> > plastic<br>
> > cover as per this page that john will appreciate, and sure<br>
> > enough the<br>
> > thing had microfractures in the ceramic board. Instead of<br>
> going<br>
> > crazy<br>
> > with tiny wires I just added a little solder and reflowed<br>
> the traces<br>
> > that the cracks were running under and buttoned it back up.<br>
> > Apparently<br>
> > Icom didn't bother putting heatsink compound on the bottom<br>
> of the<br>
> > modules and just screwed them to the board, so eventually they<br>
> > heat up<br>
> > too much and snap crackle pop.<br>
> ><br>
> > <a href="http://www.dk7in.de/TM733.html" rel="noreferrer" target="_blank">http://www.dk7in.de/TM733.html</a><br>
> ><br>
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