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I want to replace two capacitors in my LCD TV. The TV starting buzzing on dark colors, etc.

Now it started cracking and buzzing really aggressively so I opened it and found two bulging caps. I have disconnected the two internal speakers for now, which has killed the noise, but I need to replace the caps ASAP.

My question is this: When it comes to replacing caps, you can go to a higher voltage rated cap but have to stick to the same farad rating?

The bad caps are both 6.3 V, 4700 µF and i was thinking of replacing them with 16 V, 4700 µF but getting the better quality 105 °C rated one as the others ones are 85 °C rated.

Just wanted to double check before I damage my TV.

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    \$\begingroup\$ Are the replacement caps a low-ESR type? \$\endgroup\$ – ThreePhaseEel Mar 12 '17 at 17:39
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That's correct. The voltage rating is just an upper limit, which must never be exceeded in a functional circuit. Replacing a capacitor with something that has a higher voltage rating is always safe.

The only problem there is that a capacitor rated for a higher voltage is often physically larger, everything else being equal. Make sure they actually fit in the same space.

Sometimes it is also safe to use capacitors with a larger capacitance (Farads). This is not something you should experiment with unless you know the function of the capacitors in your circuit.

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The bad caps are both 6.3 V, 4700 µF and i was thinking of replacing them with 16 V, 4700 µF

Yes, you can pick a higher voltage without problems.

but getting the better quality 105 °C rated one as the others ones are 85 °C rated.

Again, yes, 105°C will last longer.

HOWEVER:

These caps are most likely at the output of a switching power supply (please check). In this case, you will have to use low-ESR (or low-Z) models rated for this use.

Consider Panasonic FC-FM-FR, Rubycon ZL, for example, but do not use "general purpose" caps in a low-Z position.

Also, please make sure the capacitors fit in the holes. Don't connect them with wires or stuff like that, as the extra inductance could increase HF ripple from your switching supply.

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    \$\begingroup\$ Please post a photo of your board (so we can try to guess the caps' role) and see if you can find a manufacturer brand and series on them. You're in the UK, right? \$\endgroup\$ – peufeu Mar 12 '17 at 12:53
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    \$\begingroup\$ @JamesMorton - "unless there is a better place to source decent components online?" Yes, there are. Rather than taking your chances on eBay, you're better off if you go to an online distributor. There are a fair number of them, and the ones that spring to mind are Digikey, Mouser, Newport, Allied Electronics and Arrow, but there are others as well. The problem with eBay is that you really have no idea of the reputation and reliability of the seller. For caps you're probably OK, but it's easy to get burned by the lowest price. Caveat emptor rules. \$\endgroup\$ – WhatRoughBeast Mar 12 '17 at 13:06
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    \$\begingroup\$ If you don't really know what you are doing, can you just always use low-Z caps to be safe? Are low-Z caps higher quality? I'm about to do a bunch of repairs on some old motherboards... \$\endgroup\$ – Daniel Sep 10 '18 at 13:14
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    \$\begingroup\$ @Daniel, some regulators become unstable if the output caps have too low ESR, so if you know the part#, look at the regulator or DC-DC datasheet. However, large capacitor values (like here, >1000µF) help with stability, so ESR is mostly a problem with low capacitor values, like 10-100µF. You should be safe. \$\endgroup\$ – peufeu Sep 10 '18 at 14:45
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    \$\begingroup\$ @peufeu So all the things I should be checking when replacing a motherboard capacitor: µF - should be equal to, V - at least equal to or higher, temperature rating - at least equal to or higher, physical size - about the same, ESR - about the same, brand - Panasonic, Rubycon, or? \$\endgroup\$ – Daniel Sep 10 '18 at 16:10

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