Half rule broken

[Fir3Chi3f]

Howdy everyone!

I've read that when replacing lytics with polys the fraud value should be about halved. https://www.badcaps.net/forum/showthread.php?t=8679

But I recently fixed a monitor before reading such, http://www.overclock.net/monitors-di...l#post12759917. So, what can I expect in the long run? The monitor seems to work fine.

Cheers

[yyonline]

Re: Half rule broken

Well...the capacitors you replaced are on a power supply board. Generally, you want to stick close to the original specs there are far as ESR and ripple. Polymer capacitors have much lower ESR compared to electrolytic capacitors. Those who understand electronic theory better than I do say that changing ESR too drastically can throw things out of tune. The ideal replacement would have been an electrolytic capacitor with similar specs from a more reliable manufacturer.

Reducing capacitance when decreasing ESR only applies to certain areas of a PC motherboard. On a power supply, keeping the capacitance the same was the right call.

I wouldn't worry too much about the reliability of the ones you just replaced. What I might worry about - I see that there are other Capxon on the board you did not replace, as well as what look like Taicon. These brands are unreliable, and I would have replaced all of them while the monitor was apart.

All things considered, good job with the repair

[Fir3Chi3f]

Re: Half rule broken

Thanks yyonline, I have a couple of motherboards and another monitor to fix and I wanted to make sure I understood these things to some extent before continuing.

Mind if I quote you for the tutorial on overclock.net? (I might redo the whole thing with the other broke monitor now knowing a bit more) I don't make a tutorial here because most here seem to understand these things a bit more than those at overclock

[Th3_uN1Qu3]

Re: Half rule broken

The thing about very different ESR is that it can change the power supply's transfer function a lot, enough for the control loop to start oscillating and not maintain proper voltage regulation anymore.

However, if the caps are low enough ESR and high enough capacitance (they always are high enough capacitance, with standard aluminum electros you have to use a lot more capacitance than needed just to get the required ESR), it may not matter if the control loop is oscillating. A monitor is a device that consumes a steady amount of power. When there are no transients, the control loop will behave even if it's not compensated properly. Regardless, if it were an issue you would have seen the effect by now.

[momaka]

Re: Half rule broken

Nice work, Fir3Chi3f! I like the pictures with the stick figure in your thread - very cool .

Like yyonline suggested, though, you should replace the rest of the CapXons as well, along with the Taicon caps.

Besides the capacitor brand name, capacitors also have a series marking (usually a 2 or 3 letter code). Different series have different characteristics (such as ESR/impedance and Ripple Current). For example, you can have two 220uF 25v caps, but one may have a different ESR and Ripple Current rating from the other cap. The brand of the capacitor, along with the series will allow you to chose proper replacements. Capacitors datasheets can usually be found online (if not, ask here ).

Ideally, you want your replacement caps to have the same or higher Ripple Current rating and same or lower ESR/impedance.
In your case, you have CapXon. The most commonly used CapXon series in monitors are usually KF and GL (and sometimes KM). Yours are black, so I would guess either KF or KM series. Based on the datasheets:

- If KF series, replace with any of the following:
Rubycon ZL, Nichicon HD, United Chemicon KZE, Panasonic FM and FR.
These will also likely work, even though they are not up to spec with CapXon KF:
Nichicon HE, United Chemicon KY

- For KM, replace with any of the following:
idealy: Rubycon YXB, Nichicon PW and PM, United Chemicon LXY and LXZ, Panasonic FC
also fine: Rubycon YXG, Nichicon HE, United Chemicon KY, Panasonic FR, Sanyo WX

As for the solid caps you used - they have much better specs than the CapXons. If you did this on a regular computer power supply, this might have been a problem, like Th3_uN1Qu3 described. Monitor power supplies, however, don't seem to mind that much. Part of this is due to the lack of large inductors and steady power draw. With that said, you can leave the solid polymers you originally installed. In fact, I think it's good to have them there since they can take heat abuse much better - and most of these monitor power supplies do get quite hot.

By the way, one more thing - the capacitance is not measured in fraud but in Farads (F) (on those CapXons, though, it may as well say FRAUD ). The μ in front means micro, or 10^-6.

[PCBONEZ]

Re: Half rule broken

When it was first created [HERE BTW] the "1/2 Rule" was improperly applied by many and bad info got spread all over the web.
-
It is based on what is said in a tech document for a VRM controller chip and outside of a VRM it does not apply.
.

If you are not working on a VRM there is nothing at all that actually says it's okay to reduce uF.
.

[PCBONEZ]

Re: Half rule broken

By the way, one more thing - the capacitance is not measured in fraud ....

Except when you buy them on eBay.

[Toasty]

Re: Half rule broken

^^^^^

+2

[Fir3Chi3f]

Re: Half rule broken

Ahh! Info-gasm! I'll need some time to pick through this, but I'm sure I'll have more questions in a bit. Thanks everyone!

Well aren't my cheeks red, typos and spell checker are a funny mix

[momaka]

Re: Half rule broken

Except when you buy them on eBay.

But the shipping is soooo fast! Don't you ever read the feedback?

Well aren't my cheeks red, typos and spell checker are a funny mix

Hey, at least you used spell check .

[Fir3Chi3f]

Re: Half rule broken

I was looking at the new broken monitor (because it's already open) and all the caps are CapXon GL. I was doing some googleing and couldn't find much on "CapXon GL" except for other blown cap tutorials/situations. http://pavel.kirkovsky.com/2009/03/s...r-204b-repair/ <- This guy miss-matches caps because he couldn't get the 820uf 25v.

So I don't have to keep coming here to ask what caps I need, Where can I find these data sheets?

Based off of voltage, farads and this chart I need Rubycon ZLK. Is this correct? I will be replacing all the caps this time.

I'll need to reopen the monitor to see what they are, thanks momaka! I actually gave that monitor to my little brother; I'll need to wait until he isn't using it.

And thanks everyone!

ps - this new broken monitor is a 22" Samsung 226BW and it will be going to my little sis when it is finished. She is using a 15" tube screen now.

edit: Yes, yes I did read the feedback and everyone else seemed so happy to give their money to him!

[momaka]

Re: Half rule broken

I was looking at the new broken monitor (because it's already open) and all the caps are CapXon GL. I was doing some googleing and couldn't find much on "CapXon GL" except for other blown cap tutorials/situations.

second link with Google search, boom!


I see your monitor also has the 820uF, 25v CapXon GL caps - check their size (dia. by height in mm). I've had both 25v 820uF and 25v 470uF CapXon GL caps, and both had the same 10mm x 20mm size.
Since the ESR and ripple current rating of a capacitor depends on its can size only (this is within the same series, of course), my 10mm x 20mm CapXons GLs were actually closer in spec to a 680uF 25v CapXon GL.

So keep that in mind when you're replacing yours, in case you have a hard time finding a replacement 820uF cap with those specs in that can size. The Rubycon ZLK you pointed may be a bit of an overkill (in terms of ESR and ripple), but they will more than likely work fine.

She is using a 15" tube screen now.

Ouch. 17" I can tolerate just fine, but 15"...
One reason I don't like using notebooks too much.
That 15" tube will probably work for many more years, though. Good to keep for a backup.

[c_hegge]

Re: Half rule broken

Except when you buy them on eBay.

+3

Except when you buy them from egekecu on eBay. I actually prefer him over here. His shipping is cheaper and they get here in half the time.

[pfrcom]

Re: Half rule broken

+3

Except when you buy them from egekecu on eBay. I actually prefer him over here. His shipping is cheaper and they get here in half the time.

Disagree with you there

Bought some Polymers from Badcaps because of Egekecu's uncompetitive pricing, and resigned myself for a long wait

Very pleasantly surprised when my shipment from Badcaps got to Melbourne in one week

Which was much quicker than my last purchase from Egekecu

[Per Hansson]

Re: Half rule broken

+3

Except when you buy them from egekecu on eBay. I actually prefer him over here. His shipping is cheaper and they get here in half the time.

I don't mean to sound like someones daddy
Or for that matter some promoter for Badcaps.net

However promoting an eBay seller over the excellent services offered by Topcat (Badcaps.net owner)
Or for that mater the services offered by Big Pope (Also a member of this site, selling Samxon caps from Hong Kong)
That just seems like a great disservice for Badcaps.net
The only reason this excellent forum exists with it's many knowledgeable members offering their advice for free is due to Badcaps.net services

[Fir3Chi3f]

Re: Half rule broken

I found another source for that same info sheet:

I've hit something of a wall however, the dimensions on these sheets do not match the dimensions of the caps I have.

Specs on my blown caps:
820uF
25v
10mmX20mm

Closest match on the spreadsheet is 8mmX20mm

Overkill doesn't sound like a bad thing, any reason I shouldn't just replace these with Rubycon 820uF 25v ZLK 10mmX20mm that are available in the badcaps store?

@momaka - I did get the other monitor back, looks like they are KF series. I will replace the rest of the caps and perhaps take those polys out. Thank you.

[PCBONEZ]

Re: Half rule broken

8x20 is very far off. Go by can size for Ripple and ESR - uF and volts don't matter for ESR.

Use the dimensions on the cap you have in hand and the specs from closest the one in the data sheet with the same dimensions.
[ESR and Ripple for whatever series are based on the can size.]
.
In the GL data sheet the 820uF *25v* is 10x25mm with ESR=.043 Ripple=1460.
.
Closest 10x20 is ESR=.052 and Ripple=1280.
.

[momaka]

Re: Half rule broken

Overkill doesn't sound like a bad thing, any reason I shouldn't just replace these with Rubycon 820uF 25v ZLK 10mmX20mm that are available in the badcaps store?

The Ruby ZLK are close in specs to Panasonic FM, and from what I've seen, Panasonic FM has been used quite a bit for monitor repairs around here and it has always worked. So the Ruby ZLK should work fine, too.

I did get the other monitor back, looks like they are KF series. I will replace the rest of the caps and perhaps take those polys out.

You can leave the polys.

[PCBONEZ]

Re: Half rule broken

Capxon KF are NOT polymers.

Small lytics don't always have vents.

[Fir3Chi3f]

Re: Half rule broken

Capxon KF are NOT polymers.

Small lytics don't always have vents.

Sorry pcbonez, I was talking about the polys I used in my first monitor repair before I was a member of this board. The picture below is taken from my tutorial on overclock.net