Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

[Spz0]

Hey there. First post, but have been reading a bunch on this site to try to resolve my query.

I have a 22" Emachines L22YCET (I know, thats the first problem. lol).
Its about 3 years old, and now the backlight is not lighting up. Exact same symptoms as a bad capacitor diagnosis -- screen turns on for 1.2 sec then backlight goes out, but lcd is still active (if I shine my headlight at the screen I can make out the image - even access monitor menu).
I first tried turning down the brightness and contrast to see if I could get a little staying power out of the monitor before it goes black, but thats a nogo.
So I've cracked the case open and taken out the power supply board to inspect for bad capacitors. Problem is, that I am seeing no bulging or leakage that would indicate a bad cap. I do not have a volt meter to run a continuity test either unfortunately. So I was thinking of just replacing all the capacitors on the board.
But before doing so, I thought I would post here to see if anyone had any insight on my particular issue.

Im attaching a pic of the power supply board. I have circled a capacitor that looks suspect -- It doesnt quite look like its bulging, but _something_ looks a bit off Im thinking -- but Im no expert. =\
(full size link below the forum pic.)

Thanks for Looking.


http://img577.*************/img577/2562/img20111027162615.jpg

[mockingbird]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Odd...

It appears as if someone has already re-capped this monitor with UCC. I'm aware that there are many imitators of their vent style, but judging from your pic - and it's not the very best pic - those look like genuine UCCs.

In which case I can't help you. If the guy replaced the originals with lower values - albeit from a good brand - then unless you know WHAT the originals were, your best bet is to find an equal value cap with higher ripple suppression, but be careful around the pi filter to match the ESR. Even your primary filter cap looks like the markings UCC puts on primaries and the starter cap has the etching that I've only seen on UCC small value caps.

Either that, or it's not the caps.

If they're not UCC caps, list all of them.

[PCBONEZ]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Check for cold solder joints.
Especially around the two inverter transformers.
.

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Odd...

It appears as if someone has already re-capped this monitor with UCC. I'm aware that there are many imitators of their vent style, but judging from your pic - and it's not the very best pic - those look like genuine UCCs.

In which case I can't help you. If the guy replaced the originals with lower values - albeit from a good brand - then unless you know WHAT the originals were, your best bet is to find an equal value cap with higher ripple suppression, but be careful around the pi filter to match the ESR. Even your primary filter cap looks like the markings UCC puts on primaries and the starter cap has the etching that I've only seen on UCC small value caps.

Either that, or it's not the caps.

If they're not UCC caps, list all of them.

This monitor came factory direct 3 years ago (New, not reconditioned), so it couldnt have been recapped unfortunately.

@PCBONEZ:
Could you describe what I would be looking for re: cold solder joints? Im not familiar with the terminology m8.

Thanks

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

To list the caps they are as follows:
(two middle right side of the board)
680uF 25Volts (x2)

(Bottom left of the board listing left to right/top to bottom)
1000uF 16Volt
1000uF 25Volt
680uF 25Volt
470uF 25Volt
470uF 16Volt.

[mockingbird]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

A cold joint occures when the solder fatigues from either hot/cold cycling, inadequate solder and age. It means that the solder is not in good contact with the pins of the through hole components (Can happenw ith SMD too). So take your iron and run it over any joints that look suspicious...

We will need more info on the caps. Series and diameter for instance.

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Im not sure what you mean by series (sorry for my noobness =\ ), but I will list diameters and unique printings for each cap.

680uF 25Volts (x2) (1cm Diam) (KZH print) (temp. (M)105oC 7(2) 7G )
1000uF 16Volt (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 5E )
1000uF 25Volt (1.2cm Diam) (KY Print) (temp. (M)105oC 6(7) 9Z )
680uF 25Volt (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 4E )
470uF 25Volt (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 6K )
470uF 16Volt. (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 7D )

Hope this helps, and Thanks in advance for Helping me

An afternote: Does height of the caps come into factor?

[retiredcaps]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

I do not have a volt meter to run a continuity test either unfortunately.

Without a multimeter or voltmeter, your troubleshooting is going to be very limited especially with 2 seconds to black. Causes can be

a) bad caps
b) bad inverter transformer
c) bad ccfl wiring
d) bad ccfls

Since the caps are UCC, they are likely good. You can only check c) and d).

More details at post #19 and #20.

https://www.badcaps.net/forum/showthread.php?t=10419

PS. I prefer that you not post inline.

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

I'll edit my initial post.
edit::: Dont have ability to edit initial post -- sry for the inline..

Looks like I'll be getting a multimeter.


I'll post back with any findings. Thanks for the post link m8, I'll give it a read over tomorrow.

[retiredcaps]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Looks like I'll be getting a multimeter.

See if you can borrow one for a few days.

[mockingbird]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

You can try to replace the caps, but like I suspected, those caps in there are from a known good brand...

Good job with the listing, but some of the info is superfluous... This is what I need:
680uF 25Volts (x2) (1cm Diam) (KZH print)

and yes, height would also be helpful...

Could you also edit your picture in paint and reference which caps go where so I can see which ones are part of the pi filter. BTW, caps are usually measured in MM, but if you don't have a ruler with MM that's OK.

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

You can try to replace the caps, but like I suspected, those caps in there are from a known good brand...

Good job with the listing, but some of the info is superfluous... This is what I need:
680uF 25Volts (x2) (1cm Diam) (KZH print)

and yes, height would also be helpful...

Could you also edit your picture in paint and reference which caps go where so I can see which ones are part of the pi filter. BTW, caps are usually measured in MM, but if you don't have a ruler with MM that's OK.

Sure thing. I'll get the height measurements tomorrow (getting late here and having trouble finding my ruler. lol).

Heres a better pic of the board, all painted up.

Theres 2 more in the upper left corner I added as well, although they are not suspect. I can't see the numbers on the large cap -- could barely read the uF on it - because its pasted to the board.

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Looking over that thread Retiredcaps posted -- I _do_ have a fuse on this board.

Im just going to have to test the fuse, caps and transistors with a multimeter before I go any further.

Unfortunately I do not know anyone with one, and I've been meaning to buy one for the past 2 years, so looks like tomorrows the day.

[retiredcaps]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Unfortunately I do not know anyone with one, and I've been meaning to buy one for the past 2 years, so looks like tomorrows the day.

You can still test for bad ccfl wiring and bad ccfls without a multimeter. Having said that, a multimeter is very useful for general stuff. Due to the recent cold snap, I had to test a few cars for weak batteries and possibly bad alternators.

What is your budget and where do you live? I can give suggestions.

PS. We Canadians do KNOW that 1cm = 10mm.

[retiredcaps]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

I _do_ have a fuse on this board.

Im just going to have to test the fuse, caps and transistors with a multimeter before I go any further.

If the fuse is on the power board by the AC plug, it is good. No need to test it. If there are multiple fuses on the inverter board, then you will need a multimeter.

A multimeter won't be able to test caps in any meaningful way.

[PCBONEZ]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Im not sure what you mean by series (sorry for my noobness =\ ), but I will list diameters and unique printings for each cap.

680uF 25Volts (x2) (1cm Diam) (KZH print) (temp. (M)105oC 7(2) 7G )
1000uF 16Volt (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 5E )
1000uF 25Volt (1.2cm Diam) (KY Print) (temp. (M)105oC 6(7) 9Z )
680uF 25Volt (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 4E )
470uF 25Volt (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 6K )
470uF 16Volt. (1cm Diam) (KY Print) (temp. (M)105oC 7(T) 7D )

Hope this helps, and Thanks in advance for Helping me

An afternote: Does height of the caps come into factor?

This might sound like I'm ragging on you.
My intent is to teach...

Caps have more specs than just uF and volts.
The most important are ESR and Ripple current.
A series/uF/volts combination can come in 2, 3 or more physical sizes.
- Lets take that 1000uF 16v KY series and 'pretend' a little about sizes.
There might be KY 1000uF 16v in 8x20mm and 8x24mm and 10x12mm and 10x16mm.
Each of those will have a different ESR and Ripple current rating.
- So, in that [imaginary] example, in order to look up the other specs we would need to know both diameter and length to find the correct cap in the data sheet.
-
That said: MOST of the time there are only one or two caps and if two they are different diameter.
In that [more usual] case the diameter is enough to find the other specs.

~

This:
680uF 25Volts (x2) (1cm Diam) (KZH print) (temp. (M)105oC 7(2) 7G )
-
Is better written something like this.
[2] 680uF 25v 10mm KZH
-or-
[2] 680uF 25v 10x16mm KZH

Doesn't have to be in that order but the rest doesn't matter or we already know by the series name.
It's easier to follow without all the extras.

Just FYI:
(M) is the uF Tolerance code for +/-20%
105oC is [obviously] the max temp rating.
We know both of those because that applies to all KZH series caps.
- In fact those apply to most caps you'll see except for the occasional 85oC cap - which should be replaced with a 105oC if it's bad.

7(2) 7G is just the factory and date codes.
The first 7 is the year [either 2007 or 1997]
(2) is the factory they were made in. (I don't have a decoder for that.)
The second 7 is the month and the G is the day.
Months: 1,2,3,4,5,6,7,8,9,O,N,D
Days: 1-26 = A-Z (upper case) Days 27-31 = a-e (lower case)
(Had to look that up. I don't care enough about the specific day to remember.).

Sometimes they move it around just to keep it simple..(Right!)

7(2)
7G

77
G(2)

The ( ) is always the factory code.
The year is always upper left.
Month and day are always in that order.

~
Most of your caps are from mid/late 2007 but there is one from mid 2006.
Production boards usually have caps made within a few months of each other.
I'm thinking the assumption that this board has been re-capped is correct.
~

Cold solder joints occur when the metal doesn't get hot enough for the solder to plate-out and bond - or when something causes a fissure in the joint.
[Common problem on large joints when they use automatic soldering machines. The bigger leads and so forth don't always get hot enough.]
They can look like cracks, grainy dull joints, like the solder beaded on the lead or pad instead of flowed [the edge of the joint should 'feather out' and not be rolled under itself like a water drop on a waxed car.]. Sometimes it will look like a circular crack all the way around the lead. [Because it is.]
- You should be able to find a zillion pics of them on-line.
.

[retiredcaps]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

An afternote: Does height of the caps come into factor?

You bet. See the middle picture at

https://www.badcaps.net/forum/showpo...8&postcount=58

PS. That is how we (meaning I) want pictures attached.

[PCBONEZ]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

G = 7
You win the jack pot.
Your cap is dated 7-7-7.

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

If the fuse is on the power board by the AC plug, it is good. No need to test it. If there are multiple fuses on the inverter board, then you will need a multimeter.

A multimeter won't be able to test caps in any meaningful way.

Yes there _is_ just that one fuse. Thanks for the info on that.

You can still test for bad ccfl wiring and bad ccfls without a multimeter. Having said that, a multimeter is very useful for general stuff. Due to the recent cold snap, I had to test a few cars for weak batteries and possibly bad alternators.

What is your budget and where do you live? I can give suggestions.

PS. We Canadians do KNOW that 1cm = 10mm.

I have visually checked over the CCFL's and they look prestine. I read over on how to test the wiring, but I dont have a spare CCFL wire to test with. I _do_ have an extra 15" monitor lying around - could I disassemble that and see if the CCFL is compatible to test?

lol I"ll keep the measurements to MM in the future. I am also Canadian, but live in Oregon with my Wife.
I have looked at some multimeters online in a "nearby" google search -- can pick up a digital for about $20-$25. Right around my budget, so thats handy.

G = 7
You win the jack pot.
Your cap is dated 7-7-7.

LoL Nice! Let's just hope the solution is a simple one eh? lol
And thank you for the information PCBonez, and everyone else thusfar. Its not harping in the slightest -- I appreciate you trying to teach me some basics here , so I can understand a little better the ins and outs.
I am a systems analyst, and have taken a few electronics classes in the past (albeit 10-13 years ago in late high school/college), but they were all very basic knowledge classes and I have not used any of that knowledge, and thus forgotten most of it. So again, I appreciate all the information so far!! Its extremely helpful!!

[Spz0]

Re: Emachines L22YCET Bad Cap symptoms, but no sign of bulging caps.

Well, I havent had time to go grab a multimeter yet, but I did test the CCFL wiring as posted in Retiredcaps post.
I have 4 CCFLs, and #1 will not light up when it is connected only to the power supply board. All other 3 wires will produce "2 sec to black" conditions (the lights are faint), but the first one will not produce even a flicker on the screen. I have tested in extreme low light conditions just to be sure.