Some doubts I have.

[PCManiacpt]

Greetings everyone.

So, like I have said on my introductory post, I have been stalking for information this forum.

I have to repair 2 PC Screens (a LG L1730SF and an HP L1740).

They are quite -old- and we were throwing them away, as the company we used to send them to be repaired were asking quite some money for each, to break down again after some months.

After the math was done, it would be cheaper to buy newer screens (with 3yrs of warranty and all) than to keep sending the screens to be repaired.

So, I got those 2 home to start my quest at repairing.

Enough of the background story...

My questions:

On the HP one, I found 2 bad caps.
On the LG one, I found 1.

Should I replace them all? all the others look ok but since the screens are quite old.. Maybe...

So, I was checking at the store for the caps and got stuck at the fact that badcaps sells like 4 or 5 different brands of caps and even of the same kind of cap, there are different "series". I tried checking the rubycon (470uF, 25V) ones, and both ZLJ and ZLG series work for what I want. So, how should I decide? Or even between the multiple brands?

My thoughs: I was thinking in going for the cheapest. Especially because it'll be the first time i'll recap and if it fails, I don't want to loose everything...

As a sidenote, the bad caps: 2 Su'scon 470uF, 25v (from the HP screen) and 1 Su'scon 1000uF, 16v (from the LG screen).

PCManiac

Sidenote: the pictures are from the HP board as I forgot to take a pic of the LG one before removal.

[budm]

Re: Some doubts I have.

I am not sure if you can get PANASONIC FM or FM series in your country, what you need for switching power supply repair are LOW ESR type with 105c rating.
I would replace them in a set of caps.
There are other suggested caps list on this site, so you can find out what you can get in your country.
The HP L1740 looks like this?
http://s807.photobucket.com/albums/y...HP/HP%20L1740/
By the way, you should post the question in the monitor forum.

[PCManiacpt]

Re: Some doubts I have.

Bummer.. Yeah I should have posted on the monitor section.. Sorry, my bad. x.x

The HP looks like that one indeed.

I was looking at this post: https://www.badcaps.net/forum/showthread.php?t=23652 and got a little dizzy trying to figure out the impedance and other things of the caps (I found out the chart for the su'scon SG series).

For example, the 25v bad caps I have (470uF) are (aprox) 8x16 but those don't appear on the chart.. x.x

The other is 10x20 (1000uF) 16v and that one is there.

--- Edit ---

Reported my post asking to be moved if possible.

[budm]

Re: Some doubts I have.

For ALL the monitor repair I have done, I only use the FM/FR and some time FC series as long as the dimensions match the original depends if you have the room or not.
So what brand of caps can you get in your country?
What ever you are going to get, just make sure the ESR (Impedance) is the same or 25% lower, the Ripple current should be the same or better, same 105c rating, longer life hour the same or better. The size will depend on how much room you have on the board.

http://www.su-scon.com.tw/en/product...r-105C/SG.html

[PCManiacpt]

Re: Some doubts I have.

Thank you for your reply. It'll be usefull indeed.

About brands I can get in my country, I have no real clue. Gotta see if I can find portuguese online stores.
I was aiming at ebay but then I remembered it should be more reliable to buy them off badcaps.com.

Gotta see what can I get at this side of the ocean.

[PCManiacpt]

Re: Some doubts I have.

(oh god.. 6Am..)

I have been searching and, I found some (few) stores but none of them say the brand on the webpage. I have inquired one of them, so I will be waiting.

Other than those, I found out I can buy panasonic at farnell and digikey. should I avoid any of those stores?

Thanks.

[retiredcaps]

Re: Some doubts I have.

I was aiming at ebay but then I remembered it should be more reliable to buy them off badcaps.com.

Ebay is full of fake capacitors. Avoid them. Buy from a reputable big name distributor or the badcaps.com store.

[selldoor]

Re: Some doubts I have.

Hi
Use Badcaps store if they have them or you can use RS electronic components, Mouser, Digikey or Farnell. Postage and min order charge might be your main problem unless you can find one with an agency in Portugal.
When you say only a few caps are bad is that on a visual check?.
If so then you need to consider changing all the caps except the big one or at least all the medium size caps plus the start up cap or else you may be doing it over again in a short time when the other caps start to fail.

[mariushm]

Re: Some doubts I have.

Maniac, if you really can't find something cheap in your country, I may be able to help you out.

I have Panasonic FM 470uF 25v in the 10mm diameter variety and I may have the 8mm version as well in my personal stock. The 10mm ones should fit in the space you have on the board, but if you really want 8mm I can double check.
I also have some quality 1000uF 16v capacitors, again Panasonic FM 10x20 mm ..

If you're interested, I'm in Romania so they would reach you within a week and it would only cost you the price I paid for them (about 0.65 euro for 1 470uF, 0.5 euro for 1000uF) , plus about 1.5 euro for stamps and envelopes.

If you don't trust me or you don't have paypal or whatever, check what the online store on this site has to offer, but the shipping would probably be a bit more since they're sent from US.

PS. Capacitors may be going bad even if they're not swelling up. It would be recommended to replace the other capacitors around the swollen ones as well.

[PCManiacpt]

Re: Some doubts I have.

Thank you for your input guys.

retiredcaps: I do know that. but I have bought some other components from one or 2 stores and I would consider them (the same 1 or 2 stores) to buy the caps. even if only to try the quality out.

selldoor: yes, was a visual inspection. And thanks for the tp, will have it in consideration.

mariushm: I will check the prices of the referenced websites by selldoor and afterwards I shall PM you. No, I don't have trust issues over the internet. Especially if it's over some couple of euros.

[PCManiacpt]

Re: Some doubts I have.

Sorry for double posting again, as the time limit for the edition doesn't let me edit the post.

I was reading about the subject, to increase my knowledge and from what I have seen, there are capacitors low ESR and caps low Impedance. low Impedance ones are advised for AC circuits and ESR for DC circuits, am I right?

[George Ortiz]

Re: Some doubts I have.

First check which model of HP L1740 you have. I have seen them with 4 different oem
power supplies. The one I am most familiar with is the Phillips power supply. The one I own starts with 715G. On these two models even after replacing the caps the problem turned out to be one or two ccfls was burnt out. The other 1740 power supply is made by BenQ. That one I am not familiar with troubleshooting. There is another power (not sure of the mfg) supply that replacing the bad caps repaired the monitor. Look at my 1st post for the Phillips power supply pictures.

[mariushm]

Re: Some doubts I have.

ESR varies according to the frequencies used in the circuit.

If a capacitor is used with a switching regulator running at 54kHz, its ESR will be different compared with it running along a switching regulator used at 72kHz or 200kHz
That's one of the reasons you don't see an ESR column in datasheets.

It's a bit simplified, but for replacing capacitors in monitors and power supplies, the Impedance column (with measurement at 100kHz) can be considered equivalent to the ESR value of the capacitor.

[PCManiacpt]

Re: Some doubts I have.

Ah, thanks mariushm.

George Ortiz, unfortunately I don't have any sticker nor plastic casing, as I had to strip it down to the bare metal since I didn't wanted to be stuck at the security guards asking me questions about it. Even though My boss knows i took it home, this is supposed to be for learning and training. Making it work is a plus.

I can show you a picture of the pcb though.

[selldoor]

Re: Some doubts I have.

Unless I have missed it you dont seem to have said what is wrong with the
monitors.( Apart from the faulty caps) May be useful to set each up - with a pc source- and tell us what happens from plug in to the final fault stage.
What is the power led doing - any sounds- anything from the panel - does it flash on briefly and so on.

[George Ortiz]

Re: Some doubts I have.

From your picture this is definitely the fourth model of power supply that I've worked on.
Your picture shows exactly the same problem the two 1740s had. I replaced the 470uf25v (2) per board and voila the monitors worked. I had a third one fail at the same two
capacitors, but replacing the caps here did not fix the problem on this one. Since I already had two other spare 1740s, I elected not to troubleshoot further. I used Panasonic caps for the two repairs.

Added note:
Here's the spec on the Panasonic caps:
470uf 25V (3 each) P12388-ND Panasonic EEU-FM1E47 @ $.50 ea *

[PCManiacpt]

Re: Some doubts I have.

Unless I have missed it you dont seem to have said what is wrong with the
monitors.( Apart from the faulty caps) May be useful to set each up - with a pc source- and tell us what happens from plug in to the final fault stage.
What is the power led doing - any sounds- anything from the panel - does it flash on briefly and so on.

You are entirely correct. I quite forgot to check that out before removing the visibly bad caps off. *doh*!

Back to when I got called to check what was wrong with the computers (the user allways says "the computer doesn't work!"..), both of them didn't turn on at all and I didn't notice any noise. Not even back to when I tested them at the informatics department. But I can't recall if the LED would turn on or not.

Well, I'll make sure to take a note next time it happens. And well, if these don't work after the recap, I'll have something more to say about them. at least am sure I'll enjoy the re-soldering and the skills I can attain from failing or succeeding to do so.

[PCManiacpt]

Re: Some doubts I have.

For ALL the monitor repair I have done, I only use the FM/FR and some time FC series as long as the dimensions match the original depends if you have the room or not.
So what brand of caps can you get in your country?
What ever you are going to get, just make sure the ESR (Impedance) is the same or 25% lower, the Ripple current should be the same or better, same 105c rating, longer life hour the same or better. The size will depend on how much room you have on the board.

So I decided to get all the caps exchanged on the 2 monitors (appart from the biggest cap like selldoor said. Based on this quote, I made came up with this:



Clickable links:

EEUFM1E471
EEUFM1E471L
EEUFM1H471
EEUFM1E681
EEUFM1C102
EEUFM1E102

on the image, the First one is in red because, that's what would match this panasonic's table ( ), but the impedance was way off so I though if I could replace with a similar yet smaller one (the EEUFM1E471L)

All the rest, was direct "mix-and-match".

So, how bad?
PCManiac

[mariushm]

Re: Some doubts I have.

Either one in the first two links will work fine.

For the 1000uF, stick to the 16v one, the 25v one may not fit on the board as it's 12.5mm. But if you think it does fit, feel free to get it, it won't hurt going for higher voltage rating.

But pay attention to the shipping costs, for my country Digikey used to charge 20$ for orders smaller than 200$ (saying used because it's a few months since I ordered last, it might still be the case).
And, you might also pay customs taxes and VAT if they're shipped to you from US, but it depends on how your country's laws are.

I'm using Farnell and RS-Online mostly nowadays, because Farnell has a flat fee of 20 RON (~4.5 euro) for any package for my country - but for other countries they have minimum order sizes and other annoyances. RS-Online has a Romanian distributor they work with and they charge only a courier fee of about 5 euro 1-2 Kg packages.

Farnell and RS-Online prices are a bit bigger than Digikey's but if you order a lot of parts, with Digikey you may get hit at customs with the 1-3% import tax and VAT (which in my case is 24%).

It's still a tad cheaper to get from Digikey in volume, but sometimes it's worth more for me to have the UPS guy at the door with the package 2 days after the order (yeah, they're really that quick, 2-3 days for stuff to arrive from Farnell's UK warehouse), instead of waiting 2 weeks to get stuff from US.

[PCManiacpt]

Re: Some doubts I have.

The links were just reference for what I had found out. I am yet to compare the prices. Just wanted to be sure I made reasonable choices.

On the LG screen I have here to fix too, It has that 1000uF 25v cap. Hence why it's there. The HP screen uses indeed the 1000uF 16v cap.

Edit: And thanks for your reply