JBL BP1200.1 blown capacitors, why?

95StangTech · 29th June 2010, 08:36 PM

I picked up a bp1200.1 for $20 at a flea market took it home hooked it a battery and as I suspected the power wire started getting hot pretty quick. I opened it up and found 5 blown capacitors, c500, 501,502,508 and 538. What would cause this and should I look elsewhere for problems?

kc7wdg · 30th June 2010, 07:01 AM

I have seen capacitors on computer motherboards and other various consumer electronics do that bubble top trick. It is generally do to cheap Chinese knock off caps. I'd be willing to bet if you replace them with good quality ones it will work just fine assuming it was not powered on for a long time with those bad caps.

kc7wdg · 30th June 2010, 07:49 AM

Quote:

Originally Posted by kc7wdg

I have seen capacitors on computer motherboards and other various consumer electronics do that bubble top trick. It is generally do to cheap Chinese knock off caps. I'd be willing to bet if you replace them with good quality ones it will work just fine assuming it was not powered on for a long time with those bad caps.

Due to cheap Chinese... rather. Also I do not envy you taking apart all that hardware to get the board up to replace them.

Khron · 30th June 2010, 09:08 AM

Samwha... Yep, quite well-known crap-cap brand

They seem to puke out their innards in Samsung LCD-TV's quite frequently. For further details on this, and good-cap and crap-cap lists and testimonies, you might wanna take a peek at the BadCaps forum. Quite an eye-opener, that

theAnonymous1 · 30th June 2010, 12:24 PM

I doubt it has anything to do with the brand or quality of the caps.

It looks like some extreme venting took place. Probably the result of a catastrophic failure in the power supply and/or amp section.

Khron · 30th June 2010, 12:47 PM

Aren't computer PSU's and mainboards "harsh enough" environments for caps? I doubt it's just a coincidence that caps from reputable brands hold up for ages, while crap ones bulge and vent even just sitting on a shelf

Of course, a(nother) malfunction isn't out of the question either. But then the question is, did the malfunction blow the caps, or did the caps cause the malfunction?

95StangTech · 30th June 2010, 07:54 PM

Khron - Exactly, which occurred first, that is my wonderings as well. What conditions would cause a cap to vent like that? I really can't tell if they are related to the power side or the audio side either, so I'm having trouble guessing what happened. Please any suggestions, anyone I would love to put this thing into use!

Khron · 30th June 2010, 08:36 PM

One thing you could try would be to check out some of the big suppliers in your area (if any; like Farnell, Digikey, Arrow, RS etc), and see how much it would cost you to do a full re-cap. If only those few caps popped, it shouldn't be too much.

Since it's a switching PSU / amp, you'll want to look at low-ESR caps; the most reputed brands would be Rubycon, Panasonic/Matsushita, United Chemi-Con, Nichicon and Elna. You can check each manufacturer's website for diagrams with their models/features.

Disclaimer: I'm only suggesting this as *A* way to go about this, not "the best"

PS: HERE you can see an example of Samwha "craftsmanship"

You'll have to register to see the photos though...

30th June 2010, 12:24 PM	#5
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	I doubt it has anything to do with the brand or quality of the caps. It looks like some extreme venting took place. Probably the result of a catastrophic failure in the power supply and/or amp section. __________________ "If you don't like funerals don't kick sand in Ninja's face." - Ninja

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30th June 2010, 07:01 AM	#2
kc7wdg diyAudio Member Join Date: Jun 2010	I have seen capacitors on computer motherboards and other various consumer electronics do that bubble top trick. It is generally do to cheap Chinese knock off caps. I'd be willing to bet if you replace them with good quality ones it will work just fine assuming it was not powered on for a long time with those bad caps.

30th June 2010, 09:08 AM	#4
Khron diyAudio Member Join Date: Jul 2005 Location: Finland	Samwha... Yep, quite well-known crap-cap brand They seem to puke out their innards in Samsung LCD-TV's quite frequently. For further details on this, and good-cap and crap-cap lists and testimonies, you might wanna take a peek at the BadCaps forum. Quite an eye-opener, that

30th June 2010, 12:47 PM	#6
Khron diyAudio Member Join Date: Jul 2005 Location: Finland	Aren't computer PSU's and mainboards "harsh enough" environments for caps? I doubt it's just a coincidence that caps from reputable brands hold up for ages, while crap ones bulge and vent even just sitting on a shelf Of course, a(nother) malfunction isn't out of the question either. But then the question is, did the malfunction blow the caps, or did the caps cause the malfunction?

30th June 2010, 07:54 PM	#7
95StangTech diyAudio Member Join Date: Jun 2010	Khron - Exactly, which occurred first, that is my wonderings as well. What conditions would cause a cap to vent like that? I really can't tell if they are related to the power side or the audio side either, so I'm having trouble guessing what happened. Please any suggestions, anyone I would love to put this thing into use!

30th June 2010, 08:36 PM	#8
Khron diyAudio Member Join Date: Jul 2005 Location: Finland	One thing you could try would be to check out some of the big suppliers in your area (if any; like Farnell, Digikey, Arrow, RS etc), and see how much it would cost you to do a full re-cap. If only those few caps popped, it shouldn't be too much. Since it's a switching PSU / amp, you'll want to look at low-ESR caps; the most reputed brands would be Rubycon, Panasonic/Matsushita, United Chemi-Con, Nichicon and Elna. You can check each manufacturer's website for diagrams with their models/features. Disclaimer: I'm only suggesting this as A way to go about this, not "the best" PS: HERE you can see an example of Samwha "craftsmanship" You'll have to register to see the photos though...

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