electronics, repairs, service manuals and datasheets discussion community for the repairs professionals and technicians
FAQSearchMembersGroupsRegisterProfilePM'sLogin/Out
Dell Ultrasharp Flat Panel, almost no image/brightness

 
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs
View previous topic :: View next topic  
Author Message
Kurtz
Guest





PostPosted: Fri Nov 19, 2004 8:08 pm    Post subject: Dell Ultrasharp Flat Panel, almost no image/brightness Reply with quote

I have a dell flat panel monitor lcd that has no brightness to the image. If i look at the monitor under a bright light i can faintly see the image.

Its not because the brightness is down, even in test mode you can barely see the "red/yellow/green/blue" message.

The model is 1504fp.

Ive opened it up but i cant go much further then that. Any ideas?

Thanks
Back to top
Guest






PostPosted: Sun Dec 04, 2005 2:34 am    Post subject: Reply with quote

Hi

I think you will find that the fault is with the inverter circiut that feeds the
cold cathod tubes (back lighting).

There are two high voltage transformers on the inverter board and if one
should go faulty, the board shuts down.

I'm in the midle of trying to source parts for one of these myself.

So cannot help any futher at the moment.

Best of luck
Ken
Back to top
JamesQB



Joined: 23 Aug 2005
Posts: 26

PostPosted: Sun Dec 04, 2005 3:10 am    Post subject: Reply with quote

Hi,

As previously said, you will have a problem on the inverter board, responsible for stepping up 12VDC or so to several hundred to run the CCFL tubes.

I have had many different faults cause these boards to either stop working completely, or one side to have a fault which causes all sections to shut down.

First check the surface-mount fuse for O/C if present. Check that none of the HV transformers have burnt windings. Check the switching MOSFETs near the transformers for S/C. Check the ballast capacitors near the HV transformers (each is across a primary winding and often 100nF).

Nearly always the fuse. I have found suppliers for some of the parts needed on these boards, so if anyone is having trouble, just say what you're searching for and I'll see if I can help.
Back to top
View user's profile Send private message
Guest






PostPosted: Wed Dec 07, 2005 10:45 pm    Post subject: Reply with quote

JamesQB wrote:
Hi,

As previously said, you will have a problem on the inverter board, responsible for stepping up 12VDC or so to several hundred to run the CCFL tubes.

I have had many different faults cause these boards to either stop working completely, or one side to have a fault which causes all sections to shut down.

First check the surface-mount fuse for O/C if present. Check that none of the HV transformers have burnt windings. Check the switching MOSFETs near the transformers for S/C. Check the ballast capacitors near the HV transformers (each is across a primary winding and often 100nF).

Nearly always the fuse. I have found suppliers for some of the parts needed on these boards, so if anyone is having trouble, just say what you're searching for and I'll see if I can help.


Hi James

Would you know where I could source the high voltage transformers from in the UK, for these boards.
I have a transformer that has burnt out windings and need to replace it.

Thanks for any help you may be able to give

PS Can supply board numbers if reqiured.

Regards Ken
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Electronic equipment repair and service manual search discussion Forum Index -> Equipment Repairs All times are GMT
Page 1 of 1

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Електроника София - Service Manuals Free Download - Prikachi - Service Diagrams

Free TV Schematics Download - HARDW.net - Pinout Master - Jabse Search - Jabse.InK  - Pulsator

Connector Pinout Forum - Новини - SnimkiOt.com - безплатен DNS - Whois разузнаване - Poblizo.com : пътешествия