Samsung LE23T52B capacitors AC or DC?

ottosump

ottosump

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Hello group, my daughters TV stopped working, looked around for a repair kit for the PSU but kind find anything so I've decided to order the bits myself. Got most of the parts however, I'm struggling on a couple of capacitors. Can I place a higher voltage capacitor in place of another, ie replace a 50v 47uf with a 63v 47uf. Also some of the capacitors from the company I am ordering from specify that they are DC, does this make any difference, as long as the polarity is correct they should be OK, shouldn't they?
Kind regards Otto



PS If you click the link below and then click on view document you'll see the reference to the right of the schematic

Samsung LE23T52B PCB BN96-02580A

http://www.4shared.com/document/2JuX0ynl/Invertor_Samsung_BN96-02580A.html

Read more: //www.diynot.com/forums/audio-visual/hot-cold-tv-pcb.292359/#ixzz1Z9BNUp2e
 
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You are fine using a higher voltage capacitor and chances are it will be better although as they are normally larger you need to make sure they can still physically fit in the space.
Virtually all of these types of capacitors are dc. Bipolar (ac) are a specific type. Just make sure the ones you get have a 105C temperature rating
 
As you clearly have no idea what you are doing; you could well kill yourself in this attempt to repair.

Do you understand that the failure, might be due to a failed resistor, which means that the 400V DC stored in the capacitor that you are about to remove, might be fully charged? When you get zapped by DC, you stick to the source..AC throws you off.

This is why the internet is dangerous. You look up, but have no idea to the dangers....and don't know if a capacitor is ac or dc. Muppet!

This person should be banned, before he is killed..."I'm gonna fit capacitors, but are they the uninvented AC capacitors, or DC capacitors"...he needs locking up before he kills himself!

LEAVE IT ALONE - YOU WILL DIE! PLEASE do not attempt a repair. There should be an admin warning to people like this.

I can only presume that you are mentally deranged, asking if capacitors are AC or DC? Thus proving your inability to repair said TV. You will most probably die, if you attempt a repair. As you know nothing.

Due to the previous quote from you; what is wrong with the TV? I'll fix it for you foc, As long as you promise NOT to touch it, as you have been told twice, that you know nothing, and WILL die if you do?
 
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PMSL

ottosump, you have been here a while so I am sure you know about mickmoody.
He does make a valid point about the 400v capacitor. You will want to leave the tv unplugged for a few hours just to make sure the capacitor has discharged before working on the psu.

Just to clarify a couple of incorrect points mickmoody made. You won't be changing any 400v capacitors. AC capacitors do exist.
 
Consider the basic design for a switch mode power supply. It turns AC to DC stores it in a capacitor then turns it back into AC at high frequency then it transforms it down and returns it to DC. Finally it takes a sample of the DC voltage and adjusts the mark/space ratio in the AC to DC bit to correct the voltage.

It's this last bit that's the problem. It is basic going around in a circle and a fault anywhere in the loop will cause the whole unit to fail. So unlike the old days when one could test with a volt meter until you found the point where the power stops and so locate the fault, fault finding is rather complex.

So if you look at most repair facilities they will not even attempt to repair a switched mode power supply. Even when an electrolyte capacitor has clearly blown likely it will have taken some other component with it.

So if your knowledge is so limited you are unaware of if you are looking at AC or DC and don't know the explosive results in connecting a DC capacitor the wrong way around then this is clearly not the sort of work you should be attempting.
 
Thanks for all the solid advice guys, x2 of the capacitors I removed had swelled & 1 was leaking electrolyte. After replacement the TV started fine, I did follow your advice and made sure that the capacitors were discharged before removal, I did get a little jolt off one cap when I tested it on my tongue, but the blister will be gone within a week.
Thanks again, Otto
 
gblades said:
PMSL

ottosump, you have been here a while so I am sure you know about mickmoody.
He does make a valid point about the 400v capacitor. You will want to leave the tv unplugged for a few hours just to make sure the capacitor has discharged before working on the psu.

Just to clarify a couple of incorrect points mickmoody made. You won't be changing any 400v capacitors. AC capacitors do exist.
Click to expand...

Explain?

Quote..http://en.wikipedia.org/wiki/Capacitor
 
Mickymoody said:
AC throws you off.
Click to expand...
That's a bit of an old wives tale. I can assure you that 250vAC will kill you just as surely as 250vDC and you won't necessarily be able to let go of it if you inadvertently took a tight grip or simply fell against it.

However, the 400v capacitor charge isn't especially dangerous. You'll most likely touch it with only one or two fingers so it won't go through your body - the shock will be localised - and, assuming that you don't instantly pull away*, you'll discharge it very rapidly so the shock will be brief.

*In fact the greatest danger is to your elbow. I've lost count of the number of times I've had a "belt" and smacked my elbow back against something hard behind me!

As regards replacing capacitors, the link I gave to "television capacitors" is for a company that claims to have sold thousands of capacitor kits to DIY enthusiasts, so I think you are overplaying the danger. Provided the equipment is fully disconnected and left to discharge for an hour, the main danger is of cutting yourself on sharp metal edges, or burning yourself with the soldering iron.
 
The 325VDC or so those caps are charged with is.. quite painful. Other than that, the worst you'll likely get is some small burns. And it's easy enough to short the cap out before you touch it. Just short the pins with a scrap screwdriver.
 
Monkeh said:
The 325VDC or so those caps are charged with is.. quite painful. Other than that, the worst you'll likely get is some small burns. And it's easy enough to short the cap out before you touch it. Just short the pins with a scrap screwdriver.
Click to expand...

I discharge them with a 10 Ohm resistor*. If you use a screwdriver blade, the dV/dt will exceed the capacitor current pulse rating and punch-through of the insulator is possible, resulting in early failure.

In other words, if the capacitor is probably OK and you plan to keep it, don't use the screwdriver trick.

* I ought to say "used to", since I retired from that game over 10 years ago!
 
You shouldn't be anywhere near a cap you don't plan to replace. ;)

Valid point, though.
 
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