[450] IC-207H repair
John Foege
john.foege at gmail.com
Tue Oct 27 23:26:32 UTC 2015
Good...hopefully w/ some thermal grease it will not happen again !!
Probably a manufacturing oversight.
On Tue, Oct 27, 2015 at 7:25 PM, K1FSY <k1fsy at vhfwiki.com> wrote:
> 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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