I have an LG LCD tv (47LC7DF-UK) the picture only comes up after numerous times turning the set on and off. I hear buzzing coming from the SAMWHA capacitors (450WV 150uF) and wonder if these are snap-in capacitors. The name is confusing and I think that I can replace them by pulling them out and pushing new ones in. However I looked at the back and see the soldered parts and wonder if I am just delusional. Does anyone have any input? Thank you!
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Re: Snap in Capacitors
caps are almost always soldered. samwha's are bad anyway, so solder in new ones. DO NOT PULL!
pics would come in handy (see the "manage attachments" section in the new post page.sigpic
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Re: Snap in Capacitors
Snap in caps feet are bent like a claw so they can be pushed down and snapped into the holes on the PCB. This allows them to stay on the board so you can flip it over to solder.
The same thing is accomplished by bending the legs sideways on regular leaded caps.
Solder makes the permanent connection there is no way you could just snap in a line voltage cap the effects of arcing if it didn't make perfect contact would be disastrous.Elements of the past and the future combining to make something not quite as good as either.Comment
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Re: Snap in Capacitors
oh, my bad there.sigpic
(Insert witty quote here)Comment
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Re: Snap in Capacitors
Here is a picture of the capacitors. Are SAMWHA capacitors okay to buy and put back in or should I buy something different? Anywhere good to get them or just go on Ebay? Also, can anyone send a link of how it is best to solder. I soldered back when I was a Boy Scout but that was quite a while to go. Thanks again!Attached FilesComment
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Re: Snap in Capacitors
FAQ on recap (excellent pictures and explanation) right here at
https://www.badcaps.net/forum/showthread.php?t=485
I like this solder video at
http://www.youtube.com/watch?v=I_NU2ruzyc4
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Re: Snap in Capacitors
Thank you very much. One more question, I think. I should discharge the energy from the capacitor since it hasn't exploded or bulged yet, so what do I do. Allow the uninstalled board to sit out of the tv for an hour or use something to discharge the energy? Thank you.Comment
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Re: Snap in Capacitors
It is best to wait about an hour for the uninstalled board to discharge, then measure the voltage on the 450V capacitors (and any capacitors over 35V) to confirm it is safe to handle.
For replacements for the Samwha LP Series, I recommend Nippon Chemi-Con KMH (or the more compact KMM) Series.My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.Comment
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Re: Snap in Capacitors
Thank you for the replacement capacitor ideas. I've been thinking, "is this problem the capacitors?" I hear the buzzing/whirring from what I think is the large capacitors, but could it be something else from what my first post explained? I also have other smaller capacitors that look to be blowing their tops, but the actual noises are coming from the two larger capacitors that I sent a picture of? Very confusing for a newbie? Thank you.Attached FilesComment
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Re: Snap in Capacitors
the 1st picture shows 450v 150uf x2, outputting 300uf. I believe parallel caps have a longer lifespan compared to a single cap. I see nothing wrong.
the second picture shows at least 3 bloated caps. This is the problem when they bloat; they lose capacitance and gets high resistance. Then they make the semiconductors take in more current than usual.Comment
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Re: Snap in Capacitors
The caps in the second picture are most likely to be your problem. replace them first.I love putting bad caps and flat batteries in fire and watching them explode!!
No wonder it doesn't work! You installed the jumper wires backwards
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Re: Snap in Capacitors
Agreed but the noises are coming from the two big capacitors.Comment
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Re: Snap in Capacitors
Replace the smaller capacitors first, if the tops of the big capacitors feel flat, leave them alone for now.
In this photo:https://www.badcaps.net/forum/attach...chmentid=16217 it looks like there is one in the top left hand corner which is actually open.
You could test the big caps with an ESR/capacitance meter.Last edited by seanc; 06-13-2010, 08:10 AM.Comment
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Re: Snap in Capacitors
Is there a better way to discharge these, I don't feel like waiting an hour and still dealing with a live capacitor.Comment
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Re: Snap in Capacitors
For a start, measure them with a DVM to see if they're holding any voltage.Comment
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Re: Snap in Capacitors
Discharging is simple. First measure, then, if theres significant voltage on it, use a power resistor like 10kOhm 10W (with old multimeter test leads connected to it) to discharge safely, then re-check for voltage.
For your actual problem, replace all of the smaller capacitors, Samwha is known to be trash, and on your pics several of them are faulty, and these that are not yet burst open, will fail soon.
I would use United Chemicon KY or LXY, Nichicon PW, Rubycon YXF or ZL, Panasonic FC,FK or FM series as replacement.
If you want to do a good job and the device is worth it, replace the larger Samwha capacitors too, with 105° long-life parts from Panasonic, Rubycon, Nichicon, Chemicon, BC Components or Epcos.
Digi-Key or Farnell is a good source for replacement parts, Ebay or local electronics stores are NOT.Comment
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Re: Snap in Capacitors
Thank you all! I think I got it now, I just need to practice a bit before actually doing it.Comment
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Re: Snap in Capacitors
In the top left corner of the first photo, a(nother) vented cap is visible (not sure if it's in the second photo as well). If that's buzzing, could it be close enough to those snap-ins to make it seem like they're making sounds?Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - ShenanigansComment
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Re: Snap in Capacitors
The placement is pretty different, but maybe the vented caps are causing the sound to come from the larger caps because they have to work harder maybe. I bought plenty of each and will most likely replace all with rubycon caps in order get rid of the samwha caps. Thank you.Comment
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Re: Snap in Capacitors
FYI-
About an hour ago, I was running my Samsung lcd tv with the back off to see what was hissing before the picture went out. I heard the hissing start and leaned closer to the power board to pinpoint the source. One of those 450v 150uF caps jumped and then exploded into flames! Scared the crap out of me, to say the least. Earlier, I had changed out the 2200uf caps like everyone else and that didn't fix my problem so I had to do something more drastic and this definitely showed me which caps are bad! Now I know what the inside of a capacitor looks like, lol. Good luck with your replacement!
P.S. My big caps had looked bulging but I read that those don't usually go bad. Live and learn. I also wondered about the snap-in aspect of the caps I ordered so I'm glad you asked.Last edited by lauriloo; 06-21-2010, 08:21 PM.Comment
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