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Hello All,
Back in June I posted a question about a failed electrolytic in my Henry 2KD
Classic. The consensus was that: 1. that the arcing and white discharge from
the cap indicated venting of the electrolyte (a confirmation of what I
thought I knew already) and 2. all the caps were probably of similar
condition, or close to it and should be replaced.
I finally got around to changing them when a friend swapped a "new" set of
caps for some gear I had. They were bought to replace caps in a Henry VHF
amp. They are Mallory 210uf, 450V, 85C (sri Rich) with the following date
code: 659-9918-371. Here's the rub.
Although there is no indication of voltage change on the panel HV meter, I
get a metallic "clink" every so often from the caps. I have used the lights
out method to look for arcs (which revealed the initial problem) and thought
I may have had an arc from the HV wiring to the panel CW/SSB switch but have
pretty well ruled that out. I can find no evidence of arcing.
I did try running them at about 500V in the amp by pulling the tubes and
running low line voltage to condition the caps. They went more than an hour
with no sound, but started again as soon as I went back to normal line
voltage.
Should I test for leakage, and if so how? Is this phenomenon well-known in
metal-can electrolytics (with a problem, obviously)? One knowledgeable member
on the reflector that I contacted directly concluded that an internal arc in
the caps would show up on the HV meter.
Without just replacing all the caps and tossing these, can someone suggest
what the exact nature of the problem is and how to isolate it, perhaps to a
single cap without buying one more and sequentially swapping it in?
Your thoughts would be appreciated.
73, Mark
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<HTML><FONT FACE=arial,helvetica><FONT SIZE=2>Hello All,
<BR>
<BR>Back in June I posted a question about a failed electrolytic in my Henry
2KD Classic. The consensus was that: 1. that the arcing and white discharge
from the cap indicated venting of the electrolyte (a confirmation of what I
thought I knew already) and 2. all the caps were probably of similar condition,
or close to it and should be replaced.
<BR>
<BR>I finally got around to changing them when a friend swapped a "new" set of
caps for some gear I had. They were bought to replace caps in a Henry VHF amp.
They are Mallory 210uf, 450V, 85C (sri Rich) with the following date code:
659-9918-371. Here's the rub.
<BR>
<BR>Although there is no indication of voltage change on the panel HV meter, I
get a metallic "clink" every so often from the caps. I have used the lights out
method to look for arcs (which revealed the initial problem) and thought I may
have had an arc from the HV wiring to the panel CW/SSB switch but have pretty
well ruled that out. I can find no evidence of arcing.
<BR>
<BR>I did try running them at about 500V in the amp by pulling the tubes and
running low line voltage to condition the caps. They went more than an hour
with no sound, but started again as soon as I went back to normal line voltage.
<BR>
<BR>Should I test for leakage, and if so how? Is this phenomenon well-known in
metal-can electrolytics (with a problem, obviously)? One knowledgeable member
on the reflector that I contacted directly concluded that an internal arc in
the caps would show up on the HV meter.
<BR>
<BR>Without just replacing all the caps and tossing these, can someone suggest
what the exact nature of the problem is and how to isolate it, perhaps to a
single cap without buying one more and sequentially swapping it in?
<BR>
<BR>Your thoughts would be appreciated.
<BR>
<BR>73, Mark</FONT></HTML>
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