More Craptastic Capacitors

[kf0rt]

Cleaned up and rewired the home theater system yesterday (now that the kids are out, I might get to use it again). All's working fine except the powered subwoofer (JBL SUB-12 from the "Venue" series, 250 watt built-in amp). Who knows when that died. Power light off and it's fused internally. Pulled it apart this morning, and what do I find?

http://www.westton.com/misc/cap1.jpghttp://www.westton.com/misc/cap2.jpg

More 2007 vintage craptacular capacitors missing their magic smoke! And a blown fuse. Hope the fuse protected the power MOSFETs. These are "Elytone" caps; I think that's the same brand I replaced in the power supply of my Samsung LCD TV a year or two back.

[N2CHX]

Looks like the backplane motherboard from a BE Fmi 1405 transmitter. The transmitter has like 64 electrolytic capacitors on the backplane to filter the supply voltage to the RF modules. I had three of these transmitters, one with two RF cabinets for twice the power and twice the fun. Within months of installation, these transmitters would start blowing these caps. Why? Because Broadcast Electronics in their infinite wisdom, used caps rated for 50 volts on a supply rail that ended up carrying 42 volts plus stray RF. That, and replacing them require disassembling the entire backplane. Then there were caps on the modules themselves that started blowing. Then there was the 300 amp supply feeder that wasn't tightened down in the one transmitter... Then there's the frequent failure of hard drives and motherboards in the exciters. I quickly learned to hate those transmitters. In the words of the guy who replaced me -- those three transmitters are a full time job. I spent a lot of time just replacing the 50 volt caps with 100 volt high temp replacements. I'd wait until we were down to about half power and then replace the whole lot. The entire project for one transmitter took about three days. The caps in the RF modules just blew anyway even after they were replaced, even with the higher voltage and temp ratings. Bad, bad design. At least the RF modules were painless to disassemble.

[NQ6U]

Underrated tantalum electrolytics, I'll bet. Even the ARRL Handbooks says to use caps that are rated for twice the expected voltage.

[KG4CGC]

managers and bean counters
Even mythology warned us against them.

[N1LAF]

Looks like the capacitors that were on my dell computer motherboard that were replaced this past summer.

Everyone with a mid-age computer shuld check their motherboards for the capacitors shown in Rob's post, The tops will be rounded for bad caps. If your computer works, and have fattened capacitors, they can be replaced for about $100 by a really good computer shop.

I used this company for my capacitor problems: http://www.gocci.com/index.html

[kf0rt]

Looks like the capacitors that were on my dell computer motherboard that were replaced this past summer.

Everyone with a mid-age computer shuld check their motherboards for the capacitors shown in Rob's post, The tops will be rounded for bad caps. If your computer works, and have fattened capacitors, they can be replaced for about $100 by a really good computer shop.

I used this company for my capacitor problems: http://www.gocci.com/index.html

Never had a mobo problem with caps here that I know of. Seems to be hitting me more in the "consumer electronics" area. Circa 2008-9, I'm thinking. The Samsung TV had this in it's power supply (replaced 4 caps, no problem since). Pull apart a $3000 TV? No problem, and it's probably worth $500 today. Now the JBL subwoofer amp. All "puffed" caps and all of the same vintage.

Hope like hell that my similar vintage Yamaha RX-1800 doesn't suffer this.

Caps are easy and cheap: http://www.mouser.com. I buy extras because otherwise the shipping would cost more than the parts.

A hunnert bucks to pay someone else? Surely you jest. This shit is fun as a DIY project.

[N2CHX]

We call those caps "pusculated".

[n2ize]

I call them by their old fashioned name, "condensers".

[WØTKX]

Lousy foreign Leyden Jars?

Rob, somebody was playing Insane Clown Posse very loud, and that's what popped yer caps. ;)

[AE1PT]

I call them by their old fashioned name, "condensers".

You would... :lol:

[n2ize]

Cleaned up and rewired the home theater system yesterday (now that the kids are out, I might get to use it again). All's working fine except the powered subwoofer (JBL SUB-12 from the "Venue" series, 250 watt built-in amp). Who knows when that died. Power light off and it's fused internally. Pulled it apart this morning, and what do I find?

http://www.westton.com/misc/cap1.jpghttp://www.westton.com/misc/cap2.jpg

More 2007 vintage craptacular capacitors missing their magic smoke! And a blown fuse. Hope the fuse protected the power MOSFETs. These are "Elytone" caps; I think that's the same brand I replaced in the power supply of my Samsung LCD TV a year or two back.

OUCH !!! That looks more like the kind of crapout I'd expect to find in an old " boatanchor"... I wonder if diode D3* has been damaged as well.

[kf0rt]

OUCH !!! That looks more like the kind of crapout I'd expect to find in an old " boatanchor"... I wonder if diode D3* has been damaged as well.


I hope not. Didn't order any diodes (but have some in ye olde junque boxe that would do). Oh, and there's a .1 uf chip cap somewhere in that molten solder blob.

I think I learned not to use Mouser's "budget shipping" too. Ordered on Sunday, supposed to be delivered NEXT Tuesday? :wtf:

[n2ize]

I hope not. Didn't order any diodes (but have some in ye olde junque boxe that would do). Oh, and there's a .1 uf chip cap somewhere in that molten solder blob.

I think I learned not to use Mouser's "budget shipping" too. Ordered on Sunday, supposed to be delivered NEXT Tuesday? :wtf:
I've ordered parts from Mouser a few times. I used their least expensive shipping choice yet I was surprised how fast the parts came... 5 days at most. The problem was that one of the parts I needed was back ordered. When it finally came, months later, I forgot I ever ordered it. Package finally arrived and I was like "what the heck is this" ?? :lol:

[kf0rt]

I've ordered parts from Mouser a few times. I used their least expensive shipping choice yet I was surprised how fast the parts came... 5 days at most. The problem was that one of the parts I needed was back ordered. When it finally came, months later, I forgot I ever ordered it. Package finally arrived and I was like "what the heck is this" ?? :lol:

I think this is something new. As I recall, their cheapest used to be UPS ground. Cheapest now is a flat rate $4.99 and apparently goes through "UPS Mail Innovations." Placed two orders on Sunday -- the cap order should be here next Tuesday. The other went UPS Ground and is "Out for Delivery" now (I'll have it today). UPS Ground from Ft. Worth to Denver is a slam-dunk 2-day deal usually.

I wish more of these places had a USPS First Class mail option. There's nothing I ordered that wouldn't fit in a small padded envelope and couldn't be shipped via Subsidized Express. :lol:

[N8YX]

If any of you folks need replacement caps in the 220-330uF/65V range, I literally have tens of pounds of brand-new, higher-quality electrolytics. Get what you need for the price of shipping - I'm never going to use all of them.

[kf0rt]

Alls I needed was a 6.8 uf @ 100v and a 4.7 uf @ 50v. None in the junquebox or the lab at work.

Got a package from Mouser today (not the caps). Huge box; may be one for the packaging Hall of Shame.

[n2ize]

Looks like the capacitors that were on my dell computer motherboard that were replaced this past summer.

Everyone with a mid-age computer shuld check their motherboards for the capacitors shown in Rob's post, The tops will be rounded for bad caps. If your computer works, and have fattened capacitors, they can be replaced for about $100 by a really good computer shop.

I used this company for my capacitor problems: http://www.gocci.com/index.html

If the computer is old, I probably wouldn't bother to change the caps. I might try to do it myself or, more likely, I'd decommission the system and get a new computer. Or, just put in a new mainboard.

[kf0rt]

Dammit. Didn't think that'd work. Replaced puffed caps with new parts; still blows fuse. Looks like the real problem may be in the power supply.

[kf0rt]

"Blown finals." This thing has a pair of IRF640 MOSFETs that drive the speaker in push-pull fashion. Both are completely shorted. Pulled 'em out and now I'm getting a power light. $2.66 apiece at Mouser.

[kf0rt]

And... she's ALIVE!

Total parts cost, $7.79 for two transistors, two caps, two fuses and three TO-220 thermal insulators. Maybe 3 hours on the bench including disassembly and reassembly (yeah, been awhile). Bought spares of everything 'cuz I wasn't going to spend $8 shipping on $7.79 worth of parts.

Now, about this #&*%#$^ computer problem...