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[AMPS] Noises in electrolytic capacitors

To: <amps@contesting.com>
Subject: [AMPS] Noises in electrolytic capacitors
From: K4SO@aol.com (K4SO@aol.com)
Date: Fri, 28 Sep 2001 22:59:27 EDT

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In a message dated 9/28/01 10:30:23 AM Eastern Daylight Time, w8ji@akorn.net 
writes:


> Just don't fall into the trap that one person does, and say that all 
> high-power bleeders or equalizers are "bad" and replace them.
> 
> The resistor does not make the capacitor heat up, unless the 
> ventilation is poorly planned around the resistor. The correct cure 
> would be to improve ventilation or move the resistors further 
> away...not to use insufficient resistance as one person always 
> suggests.  
> 
> It sounds like your Henry is OK in that regard. Just check them 
> and be sure they are within tolerance. The only drawback of a wire 
> wound resistor is any slight nick or scrape (such as bumping the 
> resistor with a screwdriver can open a wire inside the resistor if it is 
> a high resistance resistor (wound with many turns of small wire).
> 
> If you do NOT have one or more off-value resistors (or a capacitor in 
> backwards), then you have a bad capacitor. I have receiver batches 
> of capacitors that were incorrectly manufactured. 
> 
> By the way, if it made muted "popping" noises now you might need 
> to change the capacitors again because that noise (when it comes 
> from a capacitor)  is when the dielectric inside a capacitor punches 
> a hole in the insulating oxide.
>     
I do think the Henry is poorly ventilated, just because of the cabinetry. I'm 
sure it's RF-tight though. Additional fans make up the difference. I'll start 
by testing all the resistors. I guess I failed to mention that there is a 
wirewound 25 ohm, 25W unit with a diode and cap to ground on the B- side of 
things, used as a, dare I say or guess, glitch resistor? It is vitreous 
enamel, or I should say was. Virtually all of it has cracked off at this 
point. I'll be testing that one too.

I was unfortunately aware that the sound was probably the end for the cap or 
caps. The sound is not muted though, it's a resonant clink, much akin to 
tapping the can of the cap with something hard. Regardless, sounds from caps 
are never good!

Thanks again all.

73, Mark


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<HTML><FONT FACE=arial,helvetica><FONT  SIZE=2>In a message dated 9/28/01 
10:30:23 AM Eastern Daylight Time, w8ji@akorn.net writes:
<BR>
<BR>
<BR><BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 
5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Just don't fall into the trap that 
one person does, and say that all 
<BR>high-power bleeders or equalizers are "bad" and replace them.
<BR>
<BR>The resistor does not make the capacitor heat up, unless the 
<BR>ventilation is poorly planned around the resistor. The correct cure 
<BR>would be to improve ventilation or move the resistors further 
<BR>away...not to use insufficient resistance as one person always 
<BR>suggests. &nbsp;
<BR>
<BR>It sounds like your Henry is OK in that regard. Just check them 
<BR>and be sure they are within tolerance. The only drawback of a wire 
<BR>wound resistor is any slight nick or scrape (such as bumping the 
<BR>resistor with a screwdriver can open a wire inside the resistor if it is 
<BR>a high resistance resistor (wound with many turns of small wire).
<BR>
<BR>If you do NOT have one or more off-value resistors (or a capacitor in 
<BR>backwards), then you have a bad capacitor. I have receiver batches 
<BR>of capacitors that were incorrectly manufactured. 
<BR>
<BR>By the way, if it made muted "popping" noises now you might need 
<BR>to change the capacitors again because that noise (when it comes 
<BR>from a capacitor) &nbsp;is when the dielectric inside a capacitor punches 
<BR>a hole in the insulating oxide.
<BR> &nbsp;&nbsp;&nbsp;</BLOCKQUOTE>
<BR>I do think the Henry is poorly ventilated, just because of the cabinetry. 
I'm sure it's RF-tight though. Additional fans make up the difference. I'll 
start by testing all the resistors. I guess I failed to mention that there is a 
wirewound 25 ohm, 25W unit with a diode and cap to ground on the B- side of 
things, used as a, dare I say or guess, glitch resistor? It is vitreous enamel, 
or I should say was. Virtually all of it has cracked off at this point. I'll be 
testing that one too.
<BR>
<BR>I was unfortunately aware that the sound was probably the end for the cap 
or caps. The sound is not muted though, it's a resonant clink, much akin to 
tapping the can of the cap with something hard. Regardless, sounds from caps 
are never good!
<BR>
<BR>Thanks again all.
<BR>
<BR>73, Mark
<BR></FONT></HTML>

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