Trevor: Thanks for the nice comments about my site...it's good to know it's
doing some good out there!
It would not surprise me that there are other electrolytics in the radio
that may fail given enough time, especially since all electrolytic caps will
eventually die, and those in circuits that cause them to dissipate more heat
are likely to fail sooner. I also still believe that TT got a shipment of
'sick' capacitors like the ones in this Wikipedia article I have referred to
many times:
http://en.wikipedia.org/wiki/Capacitor_plague
The good news is that after all the hours you have run your radio, those
other caps haven't caused it to malfunction...yet! The average active ham
uses their radio maybe 2,000 hours per year, so your radio might be the
equivalent of 25 years of service. BTW, after about 5,000 hours since I did
the fix on the A9 board in my OII the new caps still look perfect with no
failures.
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Trevor Smith" <virago@wildblue.net>
To: <tentec@contesting.com>
Sent: Sunday, April 04, 2010 7:28 AM
Subject: [TenTec] O-II Power Board Caps
After 6 years of nearly 100% power on my O-II demonstrated the dreaded
power board failure.
Sure enough C6 was almost 1/8" taller than the other 2 caps as it pushed
upwards from the bottom - no leaks though.
I replaced all 3 with 85c 470uf/100v while I await the delivery of the
N6IE recommended caps from Mouser.
They are only ~90 cents now if you buy 10. So I also took the
opportunity to finally install the TT headphone RF filter.
Being paranoid I decided to check all the 470uf 16v that I could find
and to my horror the 2 on the SHARC board
have nice little domes just like three mile island. C230A & C230B
decouple the Codec chips and live next to the 2
filter inductors on the RHS of the Sharc board. A similar cap on the
main RX board is totally flat topped.
Anyone had these fail before? or am I the only guy with ~50,000 hours on
my O-II? (with the electric bills to prove it!)
And a big thanks to N6IE and his webpage ( N6IE.com) for all the debug
info there.
-Trevor AB5EU
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