Iiyama Prolite E481S goes dark after 1 second, blue power LED steady on

[Neon]

Hi!
I have an Iiyama ProLite E481S (Model name PLE481S-S1S) flat screen connected to my laptop using a VGA cable. The screen has been working fine for 3 years. Now it fails.

Everytime I switch the flat screen on, it goes dark after a second. The power LED, however, stays on (constantly blue, not flashing) all the time.

This posting contains 12 MB of photos to give you as much (zoomable) information as possible. Please wait for them to load and resize automatically (somehow they start loading in fullsize to be resized after a few seconds) to make your reading easier.

The flat screen was tested using two different laptops to rule out problems originating from the laptop.

The screen comes back to life for one second when I
* change its resolution in Windows
* push its "Input" button (it looks for a connection on the DVI port, doesn't find any and then switches back to the VGA connection from my laptop)

I have read some message boards where people had similar problems and I have thus exchanged some parts. I have already successfully fixed 4 BenQ flat screens where the culprits were the capacitors, but I can't get this Iiyama E481S to work again.

To change the capacitors, I followed this how-to:

http://bololo77.bo.funpic.de/e481/

Additional ideas came from these threads: (though some of the other posters had --flashing-- power LEDs, not a steady one as I do)
http://www.badcaps.net/forum/showthread.php?p=49391
http://forum.eserviceinfo.com/viewtopic.php?t=23775

But as you can see from the pictures below, the L101 and C905 joints look fine on my screen.

This is what the flat screen mainboard looked like before I started changing components:











I changed the following components:
- two capacitors: C914, C915 (is now Panasonic EEUFM1C102)
- four transistors: Q209, Q210, Q211, Q212 (was D1691, is now C5707)

Note that the two capacitors did not look damaged. I changed them anyway, just to be sure.
A brownish color can be seen where the old transistors were soldered on the main board. That color had already been there when I opened the screen
for the first time, so it must have accumulated in the 3 years of operation.

The new transistors were smaller than the old ones so I added some metal heat sinks to each transistor for improved heat dissipation. The heat sinks are fixed to the transistors by heat-resistant glue drops in each corner and there is a fine layer of thermal heat sink paste between the heat sinks and the transistors.

Their soldered joints look not nearly as neat as the capacitor's joints. I measured them and there is a working contact from the transistor pins to the PCB, though.

This is what the mainboard looks like now:







You can download a ZIP file containing all of these pictures (43MB, high-res pics) without my red markups from

http://rapidshare.com/files/43191187...vember2010.zip

Since the screen's faulty behavior did not change, some other (not yet identified) part is probably damaged. Could anybody help? Did I do something wrong, or do you have any new ideas how to get the screen running again? If you need other photos or details, please let me know.
Thanks in advance!
Andreas

[PlainBill]

Lots of luck getting any help. If you had included the pictures as attachments many of us would have been willing to help. No way am I going to wait 5 minutes for the thread to load.

PlainBill

[Neon]

Thanks for your answer. I have spent the last 30 minutes searching for the "Edit" button in this board, because I read the "Posting images" FAQ --after-- opening my thread and realized my mistake.

Since I cannot edit my post (can't find the Edit button), I am stuck. Could anybody please tell me where the button is/should be, or could a mod delete the pictures from my original post so that I can post a reply with the images as attachments?

Edit: OK, it seems editing is NOT allowed for the first post of a thread (as I can edit this post without any problems). So I think the best solution would be to have the whole thread deleted by a mod so I can post a new one.

[momaka]

Hi Neon, and welcome to the forums.

Unfortunately, you won't be able to edit your posts after 30 minutes of submission time, but you can try deleting the pictures from your ImageShack account and upload them here instead. Just as a heads-up though, the limit is 2000x2000 pixels, 1.8 MB per picture (jpg). Alternatively, you can PM a moderator.

As far as monitor goes, if you have a multimeter, check the resistance between the outputs of one of the inverter transformers and compare it to the other. The two resistances should match within 5%.

That's about as useful as I can get, however, since I'm no expert with monitors. PlainBill here knows a lot more than I do, but he helps a lot of other people as well, so his time is quite valuable and this is likely why he couldn't help you.

[Neon]

Thanks for this good idea, momaka!

I've now tried to delete the pictures from imageshack, but on that site deleting is only possible if I had made an account and uploaded them using the account.

Could a mod please simply delete the IMG links from my original post? This way it is not too much work for you, and we can continue to use this thread.

I will post the photos of "before", meaning before I started changing parts on the mainboard, in this reply. The photos of "after" will be in the following reply.

And regarding your proposal of measuring the inverter transformer resistances: where is that? The pink and light blue connectors to the left on the "both boards before" photo?

[Neon]

Attached: Photos after I changed the two capacitors and the four transistors.

[momaka]

Sorry for the late reply, haven't logged in a few days.

Originally Posted by Neon

And regarding your proposal of measuring the inverter transformer resistances: where is that? The pink and light blue connectors to the left on the "both boards before" photo?

I attached a picture with the two inverter transformers circled in cyan. With the monitor off and unplugged, use your multimeter to measure the resistance between pins 8 and 9 of each inverter transformer (again circled in cyan at the top of the picture). See what resistances you get and report back. Should be very roughly around 1000 ohms for both.

[Neon]

Thanks for the explanation.

I measured the resistance between pin 8 and 9 of TP1: 0 (zero) ohms. Same for TP2.

Just to make sure my DMM is working, I checked a resistor of known resistance (510 ohms) from my collection, and the DMM works fine.

What does that mean?

BTW I managed to ask imageshack.us for the removal of the oversized pics. This thread should be much easier to read now.

[PlainBill]

Originally Posted by Neon

Thanks for the explanation.

I measured the resistance between pin 8 and 9 of TP1: 0 (zero) ohms. Same for TP2.

Just to make sure my DMM is working, I checked a resistor of known resistance (510 ohms) from my collection, and the DMM works fine.

What does that mean?

That means that the DMM is working and you know how to use it. This transformer uses a slightly different design than most we see.

On TP1, measure the resistance between pin 8 and pins 1 through 7. I expect that you will find that one of them (possibly pin 7) will give a reading of around 1K. Then measure the resistance between the same two pins on TP2.

If you find that ALL pins on TP1 show a resistance of more than 2K to pin 8, then move on to TP2 and repeat.

PlainBill

[Neon]

Heres what I measured:

On TP1:

8-1: Overload
8-2: Overload
8-3: Overload
8-4: Overload
8-5: Overload
8-6: Overload
8-7: 196 ohms


On TP2:

8-1: 3.94 kilo ohms
8-2: 1.245 kilo ohms
8-3: 1.245 kilo ohms
8-4: 1.243 kilo ohms
8-5: 1.242 kilo ohms
8-6: 3.90 kilo ohms
8-7: 198 ohms

[PlainBill]

Originally Posted by Neon

Heres what I measured:

On TP1:

8-1: Overload
8-2: Overload
8-3: Overload
8-4: Overload
8-5: Overload
8-6: Overload
8-7: 196 ohms


On TP2:

8-1: 3.94 kilo ohms
8-2: 1.245 kilo ohms
8-3: 1.245 kilo ohms
8-4: 1.243 kilo ohms
8-5: 1.242 kilo ohms
8-6: 3.90 kilo ohms
8-7: 198 ohms

How very interesting. I could come up with all sorts of gobbledygook, but I don't have a clue what is going on here. Maybe that's because it's 6:00 AM.

Based on my experience, I would have expected a secondary resistance of about 1K ohms. 8-7 is the same on both transformers, but the lower than expected resistance implies wire that is more than twice the diameter usually used. Why?

After reviewing the pictures, pins 8-7 is the secondary, and they seem to match within .5%, which is very good. The readings on pins 1-6 imply some sort of difference in the drive circuitry. For what it's worth, this is the Royer oscillator design used on Benq (HP, Dell) monitors.

PlainBill

[Neon]

Both inverters are marked

80LL19T-1-DN 1
DARFON 423

I can't locate a datasheet of any "80LL19T" on the internet.

What I've found is this PDF containing the info in the attached picture #2, and a person from Poland who managed to get a replacement (though his board looks a little worse than mine)

I attached two more pictures of the area around the transformers.

[PlainBill]

Originally Posted by Neon

Both inverters are marked

80LL19T-1-DN 1
DARFON 423

I can't locate a datasheet of any "80LL19T" on the internet.

What I've found is this PDF containing the info in the attached picture #2, and a person from Poland who managed to get a replacement (though his board looks a little worse than mine)

I attached two more pictures of the area around the transformers.

Technically those are inverter TRANSFORMERS, not inverters. I am of the opinion that they are fine. I would check diodes D201, D202, D203, D204 for shorts.

PlainBill

[alexanna]

The solder joint on L201 looks like it could use some touch up.
Al.

[Neon]

Using the DMMs continuity checker on the four diodes in circuit I did not get any continuity. Should I run further checks on them out of circuit? Thanks for your help.

[retiredcaps]

Originally Posted by Neon

Using the DMMs continuity checker on the four diodes in circuit I did not get any continuity. Should I run further checks on them out of circuit?

To test diodes (post #14 section 7.3), see

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

edit: continuity is not an accurate way to test the diode functionality. The continuity threshold varies from multimeter to multimeter. I have seen specs as high as 1.5k ohm for "continuity" and as low as 20 ohms.

[Neon]

It's back to life! The slightly cracked solder joint on L201 was the problem, I resoldered it (pic attached) and now the screen works fine again!

Thanks a lot alexanna for finding it and pointing it out to me! And thanks to all other helpers, too!

[alexanna]

Glad you got it going.
I actually did some cheating; I was really board with all the wife’s school teacher sisters here.
I searched the net and there was some discussions about poor solder joints on the PS/inverter, so
I looked at your pictures a little closer and L201 looked funny.
In the future on pictures, a good overall shot straight down would be best.
Al.

[Neon]

I don't mind you cheating :-)
Thanks for the photo advice. Though I hope the screen will live on for a long time...

[enghijjawi]

Hi!
i have same problem of Iiyama E481S model and I have read all the articles to find solution of the same problem of my monitor.

I like to check the screen based on the schematic and follow the read voltages and compare them to see the defect.
Looked very much on the schematic of LCD screen E481S, including the planned site of http://www.elektrotanya.com and unfortunately I did not find anything.

I hope he has the experience to help me

Thanks alot for all