Dell E2009WF schematics or service manual

[SebaX75]

Hi,
I'm new in the forum and I'm searching for schematics (or service manual) to repair a monitor LCD, Dell E2009WF.
Probably the problem is in power subbly, it's product code is ILPI-090 Rev. A; Dell E1909W should have the same power supply.
Someone has this schematics or know where I can get it?

Very thanks,
Sebastian

 

[(*steve*)]

There is some worthwhile information in the sticky thread "But before you ask..."

It includes a number of sites which have service manuals etc. Did you try them?

 

[SebaX75]

Yes,
I've altready read the thread before my registration, I've already searched on google and on many forum; the site for service manual in this thread is for TV... this is a LCD monitor and my search capability has found only power supply as replacement part from China (and I don't think they publish the schematics... however the site is written in Chinese), but nothing about schematics or service manual.
If I've not the schematics I'm not able to repair something as a monitor because my experience is very limited... this is my first LCD.

Thanks,
Sebastian

 

[(*steve*)]

OK, I'll presume you've done a thorough search and I won't repeat it.

What sort of fault(s) is it exhibiting?

Can you post a photo (or photos) of the board?

What is your general level of experience with electronics, and what sort of things have you already checked for? And a possibly superfluous question: Do you have a multimeter and do you know how to use it?

 

[SebaX75]

I start from the basics ... I'm in possession of basic knowledge, I have a multimeter, and I think of using them to its full possibilities, in addition to measuring voltage and current, control of short circuits, diodes, transistors and capacitors.
My level of experience is mostly hobby, building devices from schematics (an example is the ESR meter with which I have already fixed 4 power supplies) or repairing device where faults are visible (burned or broken component).

The monitor is fully dead, no response to power on... no led, no lcd and no visible burned or broken components.

Now the power supply situation (tested components have been tested without being removed, not checked SMD component on soldering layer):
- ESR meter (test were done at 200mV, 100kHz) has not found any ko capacitor (signed in green on image);
- during the previous tests two capacitors seemed to be shorted, but this was due to a shorted fast recovery diode (signed in red), replaced but the power still does not work;
- all visible diode now are not shorted (signed in green);
- visible resistor are good (signed in green);
- without load, on the output connector, I've found pin 1 and 2 with +5V (coming from the two parallel diode), pin 3 and 4 are ground, all other pins (5-10) seems to be at 0V;
- mosfet is not shorted, but without load his resistor (0,42ohm, under the mosfet, at right... I don't remember if it's connected to source or drain) has a voltage that seems to be 0V... it's correct?
- if I reconnect the power supply to main board the voltage become unreadable and there are surge;
- if I use a 47ohm resistor as load (it require about 100mA against 5V 1,5A reported on PCB) the voltage drops across 1 and 2V;
- you can hear a faint clicking sound (about 3 or 4 at second) coming from power supply, with load seems at higher volume, but still very weak (on repair FAQ I've found "ticking noise means the regulation loop is broken somewhere", but I'm not able to search for it with my capabilities).

The photo attached in message was taken by a China reseller found during the search of schematics... I've checked component signed, with green for working and red for replaced; http://item.taobao.com/item.htm?id=13904947552&src=fromSubCenter is another point of view with soldering layer too, always from reseller.

Thanks,
Sebastian

 

[Resqueline]

In other words, the PSU works but only with no load, and it only clicks under load.
You'll need to check &/or replace the small electrolytic(s) on the primary side, circled with yellow here.

 

[SebaX75]

Yes, the concept is correct... I've wrote all the information for completeness.
The click is very low without load, but present, and to hear it I must go near PCB... the first time I heard it with an applied load.
The capacitor you circled is a 10uF - 50V... in the next days I'll order it and post for the result.

Only one more question... What is the white material that seems glue on capacitor? Can I remove it without problems or should I replace it?

For now very thanks for the help,
Sebastian

 

[Resqueline]

It's just glue of some sort to stabilise the capacitor vibrationwise. It won't be needed unless perhaps if you plan to keep the monitor in an RV or a boat or something.

 

[SebaX75]

Hi,
I've replaced the capacitor, but the power supply work in the same manner.
I paid attention to the ticking, with or without load the frequency seems the same, while with load the volume is higher.
I measured the voltages at various points to find the differences between no-load and load (47ohm resistor):
- the voltage across the source mosfet resistor (0,43ohm) there is always 0V;
- on the other power resistor (510ohm) the voltage is 0.14 / 0.15 V without load, while with load 0.30 / 0.40 V;
- the voltage across the zener diode is always 27.28V;
- on the capacitor replaced the voltage varies between 12 and 13V (with or without load);
- on fast recovery diodes in parallel you have 5V without load or 1.6 / 1.7V with load;
- on replaced fast recovery diode there are 28.55V and occasionally goes to 32.55 V, with the load voltage is not readable (varies from 2 at 35V).

If you need more information to identify the problem as well ask me and I will try to recover.

Very thanks,
Sebastian

 

[(*steve*)]

I think we need a schematic.

Can you post an image of the reverse side of the board?

 

[Resqueline]

What Steve says. It's quite cumbersome to look at those supplier photos. Anyway, the basic operation of these supplies is as follows:
R841, 842, & 843 provides the initial startup current source - charging C855 - whereafter D852 maintains the charge from a transformer winding (during normal operation(.
C855 is the power supply for the controller IC, providing gate current pulses to the switching transistor. If it's too weak the intantaneous voltage won't hold up under load.
The controller IC also monitors the instantaneous voltage across the MOSFET source resistor. If it gets too high the IC will go into protective mode (ticking).
This usually happens on overload or a short somewhere, but if the resistor has acquired a too high resistance it could happen too early.
I'll have to ask you what part #'s the original diode and capacitor had, and what you replaced them with (important: cap' brand, series, temp. rating), just to be sure.
To find problematic faults like this you really need to have an isolation transformer and an oscilloscope. A DMM won't tell you everything you need to know.

 

[SebaX75]

@(*steve*): yes, I can post the photo at higher resolution, 6MP, but probably not before than Saturday (for some days I'm not at home). Do you want only one photo or do you want I join 2 or 4 photos? Tell me what you prefer... probably I must publish it to another place due to size limit of forum. On the other side are present smd components: two IC with 8 pins and one with 14 or 16 pins, many resistor and probably capacitor and diode.

@Resqueline: you refer to a specific schematic with the nomenclature... Is it another power supply manufactured by ILPI?
The resistor you refer and that may have changed it's value, is the low value resistor on source of mosfet?
For the brand of replaced components I must return at home, but I remember other informations:
- fast recovery diode was a SF50-04, replaced with Multicomp SF56 from Farnell;
- capacitor was a 10uF 50V 105°C, replaced with another new of same values (ESR of replaced component was better than this one)... for the next order to Farnell I've added RUBYCON 50ML10MEFC5X7.
The isolation transformer is for safety rules?
I've not an oscilloscope, I can try to ask to some friends, but it's very difficult that I can find one... what bandwidth is required to examine this problem?

For now thanks, I'll post photo as soon as possible,
Sebastian

 

[(*steve*)]

The requirement for the photo is that we can clearly see the components, and on the opposite side, can clearly see all the tracks.

We need to be able to overlay one on top of the other, so both need to be similar in size and taken from directly above the board.

Don't use a flash, place the board somewhere with good ambient lighting.

The isolation transformer is so you don't kill yourself -- or at least so it's a bit harder to kill yourself. Seriously!

Almost any oscilloscope will be fine. Even 10 MHz bandwidth would be fine.

 

[Resqueline]

The part labels I referred to were from the board depicted in your links, supposedly being identical to the board you have. Yes, I meant the sub-Ohm Source resistor.

I would not use the ML series, they're just too tiny to withstand the rigors of a SMPSU. Looking at the spec's, it's only 5*7mm and can only stand 45mA ripple.
Use a physically bigger low-ESR type.

In addition to the safety issue it's also absolutely necessary to use an isolation transformer in order to be able to measure on the primary side without a bang.

 

[SebaX75]

Yes, image and my power supply are the same... I thought you had found the scheme because the notation on image was very small.
Ok for the capacitor, I'll search for another one bigger, ESR rarely is specified.
However, for now no oscilloscope found, but I've found a 350VA electronic line conditioner... it's equivalent to isolation transformer? From schematics seems that primary and secondary are separated, the only wire in common between input and output should be the earth. There is a method to test it?
Now the information on component... I've phoned at home to have the components brand:
- original capacitor is Su'Scon, new capacitor is KSC;
- on the diode there is no brand, only SF50-04 and F88, but I do not know how to go back to the manufacturer.

Thanks,
Sebastian

 

[Resqueline]

Ah, ok, no, the pic's had a mouse-over magnifier. If I had found the schematics I would've posted a link to them.
Unfortunately not all, and not even all big suppliers carry low-ESR types, and data on them are often not volunteered..
It sounds like the line conditioner could include isolation. Just ohm phase-in to phase-out to be sure.
It's the PSU under test that's supposed to be connected isolated btw. (not the 'scope as some people do, yet survive to tell the tale)..
The Su'Scon brand has a suspect reputation, like most China & Taiwan cap' manuf's has. Japanese made cap's are usually good quality.
KSC is KingSun Electronic and is Chinese.
Most cap' brands have very different cap' lines (1, 2, or 3 letters), not always easy to spot on the cap'. Would need to know.
Do you remember how much the ESR you measured on them was btw.?

 

[SebaX75]

I start from the component... KSC probably don't have other data write on the body (and before your message I don't know that there are other info on the body); Su'Scon has 0833(M) on it's body, I've wrote down this data, but not reported in previous message because I did not know what it means... Saturday I'll examine better the components.
Thanks for the information on electronic line contitioner; Saturday I'll check that between primary and secondary that there is no continuity (I can post the schematics, it's printed on the unit).
About the ESR, my meter is selfbuilded and it does not measure the exact resistance value, but it provides a value on the goodness of the capacitor; PCB and schematics (which are slightly different because D4 is not present in PCB) are visible at http://kakopa.com/ESR_meter/. For calibration I use the best new capacitor that I have and set R19 to read 1.990 mA on the multimeter, then I check the capacitor to be tested ... So'Scon value is 1.950 mA, new KSC is 1.850 mA (the lower values, identify worst capacitors).

Thanks,
Sebastian

 

[SebaX75]

Hi,
for first thing I've checked my IREM Ministatic TR35 line conditioners that combine into one unit:
- spike suppressor;
- two RF filters;
- isolating transformer;
- electronic voltage regulator.
Schematic is in attachment, however I've checked manually it and no continuity between primary and secodnary.

I've not found any oscilloscope, I started looking to buy one, but for now it is still early, I'm reading the documentation and advice on the functions.

I've uploaded the photo of power supply on PhotoBucket (maximum height available 1536):
http://i1144.photobucket.com/albums/o483/SebaX75/Electronics/ILPI-090_Front_01.jpg
http://i1144.photobucket.com/albums/o483/SebaX75/Electronics/ILPI-090_Back_01.jpg
If the picture is not quite readable, tell me, and if there is a service that allows images larger I reupload them.

Thanks,
Sebastian

 

[SebaX75]

Hi,
in this days without reply I've searched for an oscilloscope and I've bought one used on ebay... if it work correctly in this weekend I can try to obtain more information from the power supply.
What information do you need and what measure or signal check I must do?

Thanks,
Sebastian

 

[Resqueline]

Measure the voltage curveforms across C855 and R859, using the negative terminal of D850 (rectifier bridge) as ground.
Both the unloaded and loaded conditions are interesting, but you may be challenged in recording the "ticking" waveforms if your 'scope is not a "storage" type.
Be very careful (even though using the isolation transformer) as there are high voltages and potential for shorts.