Touched 3.3uF film cap with soldering iron

Kris · 4970

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Offline Kris

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on: September 28, 2015, 01:23:00 PM
Hi,

As stated in the subject line I accidentally touched 3.3uF film cap with soldering iron while building my Paramounts. It doesn't look bad to me, nothing from inside of the cap is exposed, just outer plastic is slightly melted in the corner, but I'm not sure whether I should replace it or just leave it as is.
Pictures attached.
??

Thanks,
Kris
« Last Edit: September 28, 2015, 04:57:18 PM by Kris »


Offline Zimmer64

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Reply #1 on: September 29, 2015, 08:26:26 AM
Does your DMM offer the possibility to measure capacitors?

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Offline Doc B.

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Reply #2 on: September 29, 2015, 09:29:43 AM
It's hard to say much more than that it looks like it might be OK. Best bet is to measure the DC voltage on the output (toward the headphone jack side of the cap) and see if it is within spec. Do this with no headphones plugged in. You should see the typical few volts at startup that gradually falls to zero as the cap bleeds off, same as the other channel. What you don't want to see is something like 75VDC that drops to maybe several volts but not all the way to 0, which would indicate a shorted cap creating some current leakage thru the 2.49K resistor at the headphone jack.

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Offline Kris

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Reply #3 on: September 29, 2015, 01:30:14 PM
Quote from: Zimmer64 on September 29, 2015, 08:26:26 AM
Does your DMM offer the possibility to measure capacitors?
No it doesn't unfortunately.

Quote from: Doc B. on September 29, 2015, 09:29:43 AM
It's hard to say much more than that it looks like it might be OK. Best bet is to measure the DC voltage on the output (toward the headphone jack side of the cap) and see if it is within spec. Do this with no headphones plugged in. You should see the typical few volts at startup that gradually falls to zero as the cap bleeds off, same as the other channel. What you don't want to see is something like 75VDC that drops to maybe several volts but not all the way to 0, which would indicate a shorted cap creating some current leakage thru the 2.49K resistor at the headphone jack.

Hmmm... Headphone jack in Paramounts? Am I missing something?


Offline tsingle999

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Reply #4 on: September 29, 2015, 02:02:10 PM
I believe this is a clear message from God to upgrade the caps:)

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Offline Natural Sound

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Reply #5 on: September 29, 2015, 02:17:08 PM
Quote from: Kris
Hmmm... Headphone jack in Paramounts? Am I missing something?

Switch headphones for speakers. i.e. don't plug your speakers in. Doc B fields a lot of crack questions, give him a break. ;)

FWIW I've accidentally touched my soldering iron to coupling/parafeed caps like in your photo. In my case there was no harm done.


Offline Doc B.

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Reply #6 on: September 29, 2015, 02:45:44 PM
Ah crap. We spend so much time dealing with Crack support that I just went on autopilot. Check your plate voltage on the channel in question, at the input side of the cap. If it's way low the cap is shorted.

Dan "Doc B." Schmalle
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Offline Kris

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Reply #7 on: September 29, 2015, 02:54:07 PM
Quote from: Doc B. on September 29, 2015, 02:45:44 PM
Check your plate voltage on the channel in question, at the input side of the cap. If it's way low the cap is shorted.

Many thanks Doc.


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