Specifications for Caps for a Samsung Monitor

[Jonny Accelerant]

I have acquired a dead Samsung 266CM monitor and found a YouTube video that describes how bad caps cause the problem and that they can be replaced. So last night I found a company on eBay that has a pre-made kit of about 8 capacitors that are specifically for this model monitor, for about $10.00, so I ordered one. It should arrive on Monday, about 3 days from now.

However, I have other pieces of hardware that may also be bad due to bad caps and so I would like to learn more than just what I need to repair this Samsung monitor.

During the YouTube video, the guy mentions that he purchased caps that were "approved for power supply use" or something similar, and that he purchased them from Mouser.com, but when I went there, the search parameters were very crude.

So with all that as "background", my question is how many different ways are there to specify capacitors? I'm aware of farads (capacitance) and voltage rating, and I see the spec "radial" although I'm not real certain what that means, but where did this idea that some capacitors are better suited for power supplies come from? Also, given the extremely wide variety of manufacturers, how does someone make a decision on what brand to purchase. Is there a short list of the "best" manufacturers?

What I'm doing is getting ready to open up some of this other hardware and buy caps to repair it, that may not have pre-made kits available. For example, if I pull a blown 820 uf cap that's rated at 25 volts, of all the hundreds of choices, what cap do I purchase from (for example) mouser.com? Are there pitfalls to avoid? Special purpose caps that are never suitable for anything other than something very specific? Are there high quality caps that are always better than everything else, that might cost more but have off-setting positives that make the additional cost worthwhile?

Thanks in advance for any help.

[selldoor]

Re: Specifications for Caps for a Samsung Monitor

You may have already have hit one of the pitfalls. Apart from a few sellers on ebay known to us we recommend you do NOT buy off ebay. There are many fake capacitors being sold on ebay and even the sellers may not even realise it.
They buy a bulk parcel and split them into smaller numbers or make up into kits.

There are many many posts on here regarding which caps to buy sometimes it is not possible to follow the guidance depending on where you live.

Idea is you pull a cap and find the make and series then voltage and uf.
Armed with that you try and find a datasheet and find the Ripple current and
ESR. Then you go looking for a cap that has those same or better parameters.
This may often be outside the scope of beginners so for those who ask, for most purposes we suggest Panasonic FR FM and FC in that order OR nichicon
or rubycon equivalents. Another consideration is Physical size - no good buying the "best" cap if it wont fit, so sometimes you have to get some of each.

Next we recommend Digikey or Mouser if in the US or Badcaps.net if he has the size you want. ( Mainly for PC motherboards)

You say the search parameters are crude? maybe the wrong word? They are very exact and simple to use when you have practice

In the initial search you just type in Voltage and uf eg 820uf 25v
then select panasonic then FR FC FM in the series then pick the physical size you need.

[Jonny Accelerant]

Re: Specifications for Caps for a Samsung Monitor

Thanks Selldoor for the detailed response. FYI I pay close attention and reread detailed threads multiple times, so if you post a lot of information it won't be going to waste.

Here's a picture of the actual power board.



According to the YouTube video I mentioned, the author's new caps were slightly taller than the original but he still had clearance. When I look at the clearance, I can see there is some but not much. Maybe 4 mm, maybe less.

Also from the video the large, "CD266" cap does not usually go bad and does not need automatic replacement.

Here is the vendor that I purchased the kit from:

http://www.ebay.com/itm/230554161030

Even if the kit is adequate, I'd like to learn about how to choose caps for the next time, or is it so involved that it's easier to simply as for help on a case-by-case basis?

Thanks for your help.

[Jonny Accelerant]

Re: Specifications for Caps for a Samsung Monitor

Also I think I read somewhere that the black marks on top of the capacitor indicates leaking. Too me it looks like ink, say from a felt tip pen. I imagined it was done in the factor, to mark that the capacitors were inspected.

If the black is not ink, and indicates leaking how reliable of an indicator is that? How often is a cap bad and there is no evidence of leaking or bulging? Can I assume that the caps that are not leaking or bulging are still good, and will remain so. They are the bad "CapXon" brand that I've read so much about. Should all the CapXon brand caps be replaces as a matter of SOP? If I don't get a replacement cap in the kit for a CapXon capacitor, should I order one special and replace it, just in case?

What about the non-"cannister" caps? The blue ones. I assume the "can" style caps are the "radial" that I've read about. What's the word for the "flat" style caps? Do they go bad? Leak, bulge, etc... or are they generally good?

[mariushm]

Re: Specifications for Caps for a Samsung Monitor

The ink is marker pen from the person that visually checked that another person on the "assembly line" inserted the capacitors the right way. It makes it easy for them to do "quality control".

If the tops or bottom seem a bit swollen, replace. The arge capacitors are not that sensitive so they can usually be left there, unless they have visual signs of failure.

Capacitors can go bad in time due to heat. You can test them with an ESR meter. Proper ESR meters (or LCR meters with ESR measurement) are expensive, at about $100+ , but there's some cheap esr meter on eBay at around $10-20 (which don't actually measure esr, but something close enough to give you an indication if the capacitor is outside its listed specs)

What about the non-"cannister" caps? The blue ones. I assume the "can" style caps are the "radial" that I've read about. What's the word for the "flat" style caps? Do they go bad? Leak, bulge, etc... or are they generally good?


Radial refers to the fact that there's two leads/wires coming out of them. Can is cannister, tube.. whatever. Some say can style to capacitors that have some terminals instead of leads, usually those are capacitors for high voltage and larger capacitances.
There are electrolytic capacitors that don't have long thin leads but a "bottom" that makes it easy to solder the capacitor to boards without inserting leads through the boards. Maybe that's what you understood by "flat" style.

Electrolytics bulge or go bad due to substance inside degrading, producing gas etc etc.. there's some capacitors that look like electrolytic capacitors but are polymer capacitors, these don't use electrolyte so they don't swell. There's also other types.. tantalum, ceramic capacitors.. these have their pros and cons.



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Read what it says on the capacitors.

There's a brand name (Capxon, Samxon, Samwha etc) and a series code (usually a 2 or 3 letter code), the temperature rating (usually 105c) and the capacitance and voltage rating.

You need to replace capacitors using new capacitors with the same capacitance and the same or higher voltage rating.

You need to be careful to fit the new capacitors in the place of old ones, diameter and height wise.
Besides the capacitance and voltage rating, there's two other specs that make the capacitors suitable for power supplies, monitors etc.. these are ripple measured in mA and ESR measured in ohm or mOhm (milliohm).

Your new capacitors need to have equal or better ripple value and equal or a bit lower ESR value.

These specs are listed in the datasheet of the capacitors, and you can find a lot of datasheets online ... for example I have a ton of them saved here: ftp://helpedia.com/pub/temp/datasheets/capacitors/

Datasheets have the ripple value, and instead of ESR they have one or two columns titled Impedance, and the one saying "Impedance at 100 kHz" is the one that's very very close in value to the actual ESR of a capacitor.

For example, let's say you have there A Capxon GL series, 820uF 25v capacitor.
You go and look in the Capxon GL datasheet and you find there :

Size: 10x25
Ripple : 1460 mA
Impedance : 0.043 ohm (43 mOhm)

So now you can go on Digikey.com , Newark.com , Mouser.com , and search for a suitable capacitor.
On digikey, here's what shows up for 820uF 25v : http://www.digikey.com/product-searc...0&pageSize=500

You skip the ones that have Impedance value below the old capacitor's value (give or take 10% or so) and you skip the ones that have ripple value less than about 1400 mA.

From that page, these would work :

http://www.digikey.com/product-detai...1553-ND/756069
http://www.digikey.com/product-detai...1556-ND/589297
http://www.digikey.com/product-detai...1799-ND/756315

and there's others good.

But again, this is just for a fictitious capacitor, yours may not be the same series. Check your board and determine what's best.

Forget about eBay when there's genuine stores with cheap shipping costs.

[mmartell]

Re: Specifications for Caps for a Samsung Monitor

Radial refers to two leads coming out the same end of the component. Axial is one lead coming out each end. I have yet to see an axial cap in any tv I've worked on.

Since heat kills capacitors and power supplies generate heat (as do tv's as a whole) replacing with 105c caps instead of equivalent 85c caps is a no brainer.

[Jonny Accelerant]

Re: Specifications for Caps for a Samsung Monitor

Radial refers to two leads coming out the same end of the component. Axial is one lead coming out each end. I have yet to see an axial cap in any tv I've worked on.

Since heat kills capacitors and power supplies generate heat (as do tv's as a whole) replacing with 105c caps instead of equivalent 85c caps is a no brainer.

Thank you for the highly detailed responses. I'll be re-reading this stuff regularly. In particular thanks for the explanation (above) on why some caps are better-suited for power supplies than others. I didn't know caps were susceptible to heat, however I DO know that poor quality (computer) power supplies fail often. Now I'm wondering if some of these dead PSU's I have can be repaired by replacing the capacitors.

From my research I've got the idea that there is widespread failures in computer monitors due to bad caps. Is it also well-known in the industry that bad caps cause computer power supply failures?

[lexwalker]

Re: Specifications for Caps for a Samsung Monitor

Thanks Selldoor for the detailed response. FYI I pay close attention and reread detailed threads multiple times, so if you post a lot of information it won't be going to waste.

Here's a picture of the actual power board.

That's a very familiar board. Check the attached images...


Mostly Rubycon ZLH, Panasonic FR, Panasonic FM and Nichicon PW (whatever I have in hand at that time)...

According to the YouTube video I mentioned, the author's new caps were slightly taller than the original but he still had clearance. When I look at the clearance, I can see there is some but not much. Maybe 4 mm, maybe less.

When choosing capacitors, check the diameter, height and lead pitch as well. For LCD monitor power supplies, usually the height should not be more than 20mm (some very low profile power supply boards are restricted to 16mm maximum height) and the lead pitch is mostly 5mm. As for the diameter, depends on the available space on the board. Most of the time its best to choose those with 10mm diameter for larger capacitors...

Also from the video the large, "CD266" cap does not usually go bad and does not need automatic replacement.

"CD266" is not the brand but the series/model. The capacitor brand (in your picture) is J.H, short for Jianghai (official website here). Yes, they do not usually go bad. But if they do go bad, you cannot tell directly as often they may not show any usual signs. A capacitance meter and/or ESR meter would be required to check them...

Here is the vendor that I purchased the kit from:

http://www.ebay.com/itm/230554161030

Even if the kit is adequate, I'd like to learn about how to choose caps for the next time, or is it so involved that it's easier to simply as for help on a case-by-case basis?

Thanks for your help.

And the seller does not even show the series/model of capacitors being sold. Often we keep a stock of low ESR capacitors of commonly used values for LCD monitors. Quite often we stick to certain brand and series (for their ESR and ripple current specifications) to cover most of the replacements required...

[Jonny Accelerant]

Done!!

I'd like to thank everyone that helped in this thread. I just finished putting it back together and am very pleased to have this nice monitor. Note that at the beginning of the thread, this monitor was destined by be electronic scrap.



Note the actual color is a brilliant white. Not sure why the phone/camera wanted to make it pink-tinged. The resolution on this monitor is spectacular! Well, at least to me. I know there will be "monitor snobs" that will look down their nose at my garage floor special, but I think it's GREAT. And for less than $11.00 and about 3 hours of my time.

I'm so motivated now that I'm going to go right into another project, an ACER AL1916W that came from a client's office. It's been in the closet, dead, for about a year. I've already opened it up and it has at least two bad caps. I'm going to start another thread for this monitor, and then I'll post a link to it from here. Thanks again to all.

[Jonny Accelerant]

Re: Specifications for Caps for a Samsung Monitor

I've started another thread, asking for help in choosing caps for an Acer LCD monitor. Any help there would be appreciated. Thanks again to all who posted. I've re-read this thread at least 4 times, and have learned something new each time, for which I am appreciative.

https://www.badcaps.net/forum/showth...567#post478567

[Jonny Accelerant]

Re: Specifications for Caps for a Samsung Monitor

From my research I've got the idea that there is widespread failures in computer monitors due to bad caps. Is it also well-known in the industry that bad caps cause computer power supply failures?

I have about 20 mostly bad power supplies for desktop computers collecting dust. I've successfully replaced the caps in one monitor, and have the 2nd monitor project underway. I have about 4 more monitors that can be done. Once those are done, is it worth my time to disassemble and starting hunting for bad caps on these PSU's? Do caps cause failures in PSU's like they do in monitors?

[selldoor]

Re: Specifications for Caps for a Samsung Monitor

Haha your hooked on this now eh? PSUs also have bad caps basically thay are just the same as a monitor psu, just more power. I have been lucky and fixed one or two that just had bad caps but if its anything else I think they are difficult to work on as everything is packed in tight. Some guys on here do amazing repairs and upgrades on them and are really helpful and will talk you through it. Its good you have a few as apart from caps (its usually the same ones that go) you might be able to scavenge parts from some of them. Read through some of the threads in the Power supply design...... forum