Second opinion on replacement caps

[secular]

I have a LG l204WTX which doesnt turn on, and has been sitting around for 3 years or so now. Back in the day it would sometimes turn on and function normally just by unplugging/plugging in the power cable. it would continue to work as long as it didnt turn off or go into sleep mode.

Anyways, its completely dead now (and has been for 3 years), with only a rapid flashing blue/yellow light. I probed around and the 5V rail going to the controller board read at 5vs. The 15v rail however was at 18V. Could be a problem, could just be because the LCD (backlight and data) and VGA/DVI was disconnected and that was the unloaded voltage.

What I did notice were some bulging caps. The caps are SAMXON GF(M)'s.
The two that are bulging (and are on the 5v rail) are 16v 1000uf (V8A markings, red arrow),
the two short ones (on the 15v rail) 680uF 25v (V8A markings, blue arrow),
and the tall one between the two bulging is 25v 1000uf (V9A markings, yellow arrow) (also connected to the 15v rail)
I think this is the correct datasheet (found from another post on here)

I dont see anything about the ESR of the caps, but the ripple is 1.2A and the inductance is 60mOhm.

Searching digikey I found these and I'm hoping that someone can give me a second opinion on these caps. I think they should work. The height restriction is 23mm at most, the current caps are ~16mm.
Nichicon HW, data sheet here
680uf, 25v, 30mOhm, Ripple current 2A
1000uf, 16V, 30mOhm, Ripple current 2A
1000uF, 25v, 19mOhm, Ripple current 2.5A

I'm concerned about the ESR rating of these caps, or rather, the lack of the rating.

Why does both the Nichicon and the SAMXON have no ESR rating?

thanks for the help!

[retiredcaps]

Re: Second opinion on replacement caps

I'm concerned about the ESR rating of these caps, or rather, the lack of the rating.

The impedance parameter in the datasheet is ESR.

[secular]

Re: Second opinion on replacement caps

Thanks for clearing that up. Any thoughts on the replacement caps? Im concerned about the difference between the 'esr' or inductance rating. The caps I found have half the ESR rating. The SAMXON are designed to be "low impedance caps", therefore I would think that the design of the circuit would be independent of the cap ESR. So maybe lower ESR caps wouldnt affect the circuit?
I'm having trouble finding caps with similar ESR rating that fit within the height restrictions, and are with the same manufacturer. I suppose having different manufacturer caps in the same circuit wouldnt be a big deal.

[secular]

Re: Second opinion on replacement caps

I'm thinking the PW series might be better. The impedance is closer to whats in there now.
Nichicon PW Datasheet

680uf, 25v, 52mOhm, 1.22A, 10/20mm
1000uf, 25v, 38mOhm, 1.66A, 12.5/22mm
1000uf, 16v, 52mOhm, 1.22A, 10/20mm

VS

680uF 25v, 60mOhm, 1.21mA, 10/16mm
1000uf, 25v, 46mOhm, 1.4mA, 10/20mm
1000uf,16v, 60mOhm, 1.21mA, 10/16mm

[PeteS in CA]

Re: Second opinion on replacement caps

Thanks for clearing that up. Any thoughts on the replacement caps? Im concerned about the difference between the 'esr' or inductance rating. The caps I found have half the ESR rating. The SAMXON are designed to be "low impedance caps", therefore I would think that the design of the circuit would be independent of the cap ESR. So maybe lower ESR caps wouldnt affect the circuit?
I'm having trouble finding caps with similar ESR rating that fit within the height restrictions, and are with the same manufacturer. I suppose having different manufacturer caps in the same circuit wouldnt be a big deal.

I'm thinking the PW series might be better. The impedance is closer to whats in there now.
Nichicon PW Datasheet

680uf, 25v, 52mOhm, 1.22A, 10/20mm
1000uf, 25v, 38mOhm, 1.66A, 12.5/22mm
1000uf, 16v, 52mOhm, 1.22A, 10/20mm

VS

680uF 25v, 60mOhm, 1.21mA, 10/16mm
1000uf, 25v, 46mOhm, 1.4mA, 10/20mm
1000uf,16v, 60mOhm, 1.21mA, 10/16mm

In reverse order, I was going to suggest considering Nichicon's PW series (or UCC/NCC LXZ series; or Panasonic's FC series). As you pointed out in the second post I quoted, the characteristics are more similar. All three vendors' series should be reasonably available and not too expensive.

Impedance is the vector sum or the capacitive reactance (X(C)), the inductive reactance (X(L), aka ESL), and the Equivalent Series Resistance (= ESR). X(C) and X(L) are like adding a positive and a negative number, partly cancelling each other, but the X(C) of relatively large value electrolytic caps is so tiny that it is not relevant.

Back in the 70s and into the 80s, with 20KHz-30KHz switch frequencies, ESR was the far more significant part of impedance, so cap manufacturers gave that value in their datasheets. from the 80s onward, switch frequencies greater than 50KHz became common, and ESL became more relevant. So cap manufacturers started specifying impedance rather than ESR.

ESL is related to the mechanical construction and installation of the caps - the lead length, the length of the foils inside (for a given value/voltage a taller part has shorter foils and slightly lower impedance than the same value/voltage part).

ESR has to do with the resistances of the leads, the foils, and especially the electrolyte. The electrolyte is not the dielectric. Different low impedance series can easily use the same leads and foils, but what differs from series to series is the conductivity of the electrolyte.

A lot of people here use "ESR" in discussion, because it's easier to type and/or eplain than "impedance". Then there's OCD technoid lifeforms like me, , who type "impedance", .

[secular]

Re: Second opinion on replacement caps

Thank you for explaining that. I ordered the PW series. I'll report back if it fixed the monitor.

[secular]

Re: Second opinion on replacement caps

Replacing those two bulging caps fixed it. Thanks for the help!

[G-Laser]

Re: Second opinion on replacement caps

So, I have a few caps that I need to replace on a motherboard. These are OST's..




The RLG spec doesn't mention the impedance. Using math power (a gene I wasn't gifted with), is there a way to calculate this?
My plan is to replace these caps with higher quality ones as well as stepping up the voltage rating just to give myself a bit more headroom(IE: 6.3v to 10v). It seems that knowing the impedance would be important but I'm not sure if I should just take a guess and pull the trigger.
BTW: Caps I need to replace are.
RLX
470uf 16v 105c

RLG
1000uf, 10v, 105c
100uf, 16v, 105c

RLP
1000uf, 6.3v, 105c

[secular]

Re: Second opinion on replacement caps

choosing a capacitor with a higher voltage rating probably wont make a difference. A reputable manufacturer would make a larger difference (and you said you were doing that). If you look for a capacitor with a higher voltage rating, be careful about the dimensions. You could run into a space issue.

As for the impedance rating of the RLG, I cant give you a definitive answer. If you cant find a spec, I would use a cap with similar impedance to one of the other series. I'm guessing here, but the other two series (RLX, RLP) specifically state that they are low impedance. The RLG was probably used to save money as the ESR in that part of the circuit isnt critical.

I'm sure someone else can provide more useful information.

Side note to the OP.
I metered the caps I took out of the circuit board. I thought it was interesting to see just how much capacitance was lost. both caps were suppose to be 1000uf, but read as ~330uf and ~110uf.

[PeteS in CA]

Re: Second opinion on replacement caps

G-L, the Ost RLG series is a general purpose 105C series. I'd suggest using Nichicon PW, Panasonic FC, or UCC LXZ series parts. As secular said, you shouldn't gain anything by buying higher voltage parts, and you may complicate your task needlessly.

[G-Laser]

Re: Second opinion on replacement caps

G-L, the Ost RLG series is a general purpose 105C series. I'd suggest using Nichicon PW, Panasonic FC, or UCC LXZ series parts. As secular said, you shouldn't gain anything by buying higher voltage parts, and you may complicate your task needlessly.

Thanks!
I took your advice and looked up those caps.
For the 1000uf/10v/105c, it seems like both the Pan FC and UCC LXZ have a higher ripple than the Nichicon PW and a lower impedance. All are over the 520 ripple of the OST.
For the 100uf/16v/105c, it's pretty much a wash.

Now, I've read in other posts that a higher ripple is better. Please correct my if I'm wrong.
Also, I was to understand that upping the voltage would give the caps a bit more headroom. Since I've confirmed that the caps would fit, are there any other reasons why I shouldn't do that? What are other complications?
Any info would help clear up any confusion I might have (AKA: Need to learn more).

[Jonny Accelerant]

Re: Second opinion on replacement caps

Any info would help clear up any confusion I might have (AKA: Need to learn more).

What they told me is that newbs don't really need to worry about ripple, and also from what I've read the Pan FC are older and the Pan FM are a good, multipurpose, "one size fits all" capacitor. The Pan FR series are the newest and presumably the best but I could not find a distributor in the US, as they are "too new". Also, in general I gather that ripple is bad and the less you have the better off you are, but I think the primary quality of the cap you need to think about is how long it lasts and everything else is secondary to that. Someone should correct me if I'm wrong.

[G-Laser]

Re: Second opinion on replacement caps

What they told me is that newbs don't really need to worry about ripple, and also from what I've read the Pan FC are older and the Pan FM are a good, multipurpose, "one size fits all" capacitor. The Pan FR series are the newest and presumably the best but I could not find a distributor in the US, as they are "too new". Also, in general I gather that ripple is bad and the less you have the better off you are, but I think the primary quality of the cap you need to think about is how long it lasts and everything else is secondary to that. Someone should correct me if I'm wrong.

LOL. Well, if you're implying that veterans do need to worry about it, I would suspect newbs should worry more. I always worry more about what I don't understand but I suspect you're saying that unless you're creating complex circuits, something newbs aren't doing, they shouldn't worry about it. I'm just concerned since I'm repairing someone else's complex circuit.
As far as ripple, I have a very high level understanding of this and not very complete. I was just going by what I read in another thread on this forum.

[Jonny Accelerant]

Re: Second opinion on replacement caps

As far as ripple, I have a very high level understanding of this and not very complete. I was just going by what I read in another thread on this forum.

The point is that ordering replacement caps does not require a "high-level" understanding of ripple, and how that relates to purchasing replacement caps. It's not a factor for consideration. I would think cap diameter in particular, as well as voltage rating, max temperature etc... would be more a important concern.

And I wasn't implying anything about vets; I'm saying that they have said to me that a newb learning how to do basic cap replacement doesn't need to worry about ripple. All circuits are "someone else's complex circuits" when doing cap replacement, and of all the threads that I have read, not once has anyone been advised to choose one capacitor over another due to specific qualities regarding ripple. Almost always the decision is based on how high the voltage is going to get, for how long and how hot the capacitor is going to get. I've never read a thread where any other spec has been sacrificed in order to maximize the performance benefits of one particular capacitor due to it's special characteristics regarding ripple. I have a very low understanding of ripple, but I know enough to know that one you've limited the scope of possibilities to top-quality components, "ripple" as a standalone specification is not important.

[c_hegge]

Re: Second opinion on replacement caps

What they told me is that newbs don't really need to worry about ripple, and also from what I've read the Pan FC are older and the Pan FM are a good, multipurpose, "one size fits all" capacitor. The Pan FR series are the newest and presumably the best but I could not find a distributor in the US, as they are "too new". Also, in general I gather that ripple is bad and the less you have the better off you are, but I think the primary quality of the cap you need to think about is how long it lasts and everything else is secondary to that. Someone should correct me if I'm wrong.

The point is that ordering replacement caps does not require a "high-level" understanding of ripple, and how that relates to purchasing replacement caps. It's not a factor for consideration. I would think cap diameter in particular, as well as voltage rating, max temperature etc... would be more a important concern.

Wrong. First of all, ripple should be a concern. You should always make sure your replacement caps match or exceed the ratings of the originals. You don't need to be an expert on it, but to say you don't even need to consider it is not accurate. It is important to at least bear the ratings in mind when choosing replacement parts.

Second, there is no such thing as a one series fits all cap. Panny FM and FR do have decent ripple and ESR specs on paper, but sometimes, they can be too low ESR. Changing the ESR considerably can, in some power supplies, upset the feedback circuit.

If the original caps had similar specs to Panny FC (like CapXon GL), then the best replacement if a Panny FC

[Jonny Accelerant]

Re: Second opinion on replacement caps

Wrong.

Well I'm glad we've got that all cleared up then.

[G-Laser]

Re: Second opinion on replacement caps

Well I'm glad we've got that all cleared up then.

Hehe. It stings but in the end, we're smarter so it's a win.


Learning sometimes hurts

[Almighty1]

Re: Second opinion on replacement caps

The Pan FR series are the newest and presumably the best but I could not find a distributor in the US, as they are "too new".

Im also a newb, just slightly a slightly older newb. LOL. In any case, I recently ordered Panasonic FR series from Digikey.com or rather my first capacitor order ever and I'm sure Mouser.com probably sells it too.

[Agent24]

Re: Second opinion on replacement caps

Wrong. First of all, ripple should be a concern. You should always make sure your replacement caps match or exceed the ratings of the originals.

Second, there is no such thing as a one series fits all cap. Panny FM and FR do have decent ripple and ESR specs on paper, but sometimes, they can be too low ESR. Changing the ESR considerably can, in some power supplies, upset the feedback circuit.

Yes. If you know the specifications of the original capacitors, you should make sure your replacements make sense.


As the exception, I think the one series fits all concept only applies when the capacitors you're replacing were made by HongKongFlyApartCo or such and no datasheet is available, in which case you have no real choice but to use a middle-of-the-road Low ESR or General Purpose series (this will depend on the circuit in question) from one of the decent brands.

[G-Laser]

Re: Second opinion on replacement caps

OK, so here is what I found. I'm breaking it up into what I currently need to replace (Have) and what I want to replace it with (Replace). I have stuck to replacement caps as close to the original spec as possible. All bad caps are OST.
Please give me your two cents.

Have: RLX 470uf 16v 105c ( )
Replace: Nichicon HN (https://cdn.badcaps-static.com/pdfs/...cf99a3fb27.pdf)

Have: RLG 1000uf, 10v, 105c (http://www.ost.com.tw/pdf/EC/RLG.pdf)
Replace: Panasonic FC ()


Have: RLG 100uf, 16v, 105c (See spec above)
Replace: Nichicon PW()

Have: RLP 1000uf, 6.3v, 105c ()
Replace: Nichicon HV (https://cdn.badcaps-static.com/pdfs/...f9d746a355.pdf)

Thanks,