Iiyama 2607WS suddenly dead

[formatthias]

Hi guys,

yesterday my screen suddenly turned off. Tried to bring it up again, no chance. Power LED stayed off. Today I disassembled the screen and measured some voltages without load.
Fuse is ok, AC line is ok. No burned parts, no cold solder joints. But I can only measure 0.5V at the output to the controller board.
Any suggestions which part could be broken?

[UniT3d]

Re: Iiyama 2607WS suddenly dead

Hmmm .....

Could you kindly remove those inline pics and put them as attachments?

This particular page loads really really slooww ...

[selldoor]

Re: Iiyama 2607WS suddenly dead

I second that
pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

[tom66]

Re: Iiyama 2607WS suddenly dead

There are some fuses which can be checked, as well as some diodes (diodes should not read short.)

[formatthias]

Re: Iiyama 2607WS suddenly dead

Sry, I cannot edit the first post.

[jetadm123]

Re: Iiyama 2607WS suddenly dead

On the upper left of your first photo, next to the white connector, there are two 5A fuses. Check them for continuity.

[formatthias]

Re: Iiyama 2607WS suddenly dead

Both are ok.

[tom66]

Re: Iiyama 2607WS suddenly dead

OK, do you see the diodes on the heatsinks, near the fuses?
Check if any have shorts between the pins -- check pins 1-2, 2-3, and 1-3.

[ratdude747]

Re: Iiyama 2607WS suddenly dead

Sry, I cannot edit the first post.

...But he reported the issue and I converted the offisite inlines to onsite inlines (since you already attached them to another thread, all it took was a change of image address).

Thank You for actually reporting the issue... you'd be surprised how many people don't and just say "I can't, wah!" and don't let anybody who can help know.

As for the broken device, I second the comment on the fuses. Fuses are always a good place to start.

[budm]

Re: Iiyama 2607WS suddenly dead

What DC voltage do you get on that large brown cap measuring right at the two legs?

[formatthias]

Re: Iiyama 2607WS suddenly dead

Thanks. Ok, now I measured the diodes on the heatsinks. The upper two have continuity in both directions.

[formatthias]

Re: Iiyama 2607WS suddenly dead

The large brown cap holds 320V DC.

[jetadm123]

Re: Iiyama 2607WS suddenly dead

At this point, I suggest measuring the voltage of each pin at the white connector. If you continue to see 0V, then I'd conentrate on Q100. It appears to be a PWM controller and switching mosfet all in one package.

[formatthias]

Re: Iiyama 2607WS suddenly dead

I think the two diodes are broken. Types are MBR2045CT and MBR20100CT. The mosfet is a K3673. Do you think the diodes died with the mosfet?

[jetadm123]

Re: Iiyama 2607WS suddenly dead

Oops! Missed your earlier post about the diodes. If they are suspect, you'll have to pull them off the board and measure them again out of circuit. Very rare that they both fail. Is the K3673 also showing shorted?

[formatthias]

Re: Iiyama 2607WS suddenly dead

How can I measure a mosfet exactly? Tomorrow I will solder out the two diodes and test them again. Here it is 21:33PM. Thank you so far.

I measure 0.5V on the connector. Tells me something is wrong with the AC-DC conversion in the upper left corner.

[jetadm123]

Re: Iiyama 2607WS suddenly dead

You can test the mosfet using the same method as tom66 suggested in post #8

[budm]

Re: Iiyama 2607WS suddenly dead

OK, let see if you actuall has shorted circuits at the Cathode of the secondary side power supply rectifier Diodes. Also try heating up the startup cap to see if it will startup if there is no shortes found on the secondary side.

[formatthias]

Re: Iiyama 2607WS suddenly dead

How can I heat up the cap? Here is a picture of the measured diodes. It is not a regulator. It is a MBR20100CT.
Mosfet seems to be ok.

[budm]

Re: Iiyama 2607WS suddenly dead

Are you actually getting the 12v. The one that show 0V that's a regulator which takes the output of the diode that you show 0.5v, that is what it looks like from the traces.
Correction1, I look at the traces again, there is another winding feed that Diode not the regulator, you are right. There are three secondarywindings on this transformer. If you are getting 12v, then the primary side drive circuits muat be working otherwise there will be no any out puts.
What are the resistnace reading between the Ground and all 3 center pins of the 3 diodes?