I agree about the use of "surplus" or NOS electrolytics. Don't use them no
matter how tempting. Just because they are unused doesn't mean they are good.
They may be the same age, or older, than the component you are replacing.
Replace them with the new, smaller components. Leave the old multi-section can
in place on top of the chassis and put the new caps under the chassis, if
possible. An alternative is to replace the "guts" of the can with new caps. I
haven't done this (yet) but I have seen some very good results in units worked
on by others.
George, I'm glad to hear your TR-4 survived due to your quick reflexes!
Ken, WA2LBI
[EMAIL PROTECTED]
"Gailey, Bill" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
08/01/2003 08:49
To: "'john'" <[EMAIL PROTECTED]>, "George, W5YR" <[EMAIL
PROTECTED]>, Jim Shorney
<[EMAIL PROTECTED]>, [EMAIL PROTECTED]
cc:
Subject: RE: [drakelist] Should I get rid of my 7 line?
George, Your comment is very true for solid state and of course even more so on
the older vintage tube gear. One short story I'll share that confirms your
concerns about caps: I had recently replaced a two-section can in my AC-4 with
a 'surplus' can electrolytic. Only days later, one of the sections shorted
internally leaving the -60 volt bias gone. I was fortunate to be watching the
TR-4 warm up. In 10 seconds or so, the plate amps went flying to the right on
the meter, the finals started glowing red, and I grabbed the off switch
immediately. So glad I was not up getting coffee. Took about an hour to
understand what had happened. I replaced the cap, this time with known brand
new small format electrolytics and all has been fine since.
73,
Bill KG4KKI
-----Original Message-----
From: john [mailto:[EMAIL PROTECTED]
Sent: Friday, August 01, 2003 6:46 AM
To: George, W5YR; Jim Shorney; [EMAIL PROTECTED]
Subject: Re: [drakelist] Should I get rid of my 7 line?
At 12:20 AM 8/1/03 -0500, George, W5YR wrote:
>The likelihood of a microprocessor or other such complex chip failing in a
>modern radio - barring a lightning hit - is so small as to be negligible. In
>fact, barring infant mortalities on all the electronic parts these days, the
>failure rate is just about non-existent. Once a radio has survived the first
>few months, it is just about cast in concrete.
In general this is very true! The one "gotcha" in this equation
is still the lowly electrolytic cap. These things have lifetimes that are
many
many times shorter than the semiconductors they're adjacent to.
I think it's this technology that's going to start haunting us
as solid state gear ages.
73
John
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