DELL 1707FPt Turns on but goes black

[dexter4000]

I just a used dell monitor of ebay for $5 but the action did not say anything about it not working.

I plugged it in and power it up, powers up for like 3 sec and then goes black. A buzz/humm is heard during the fade to black. The power button is sill lit but the screen is black. Im assuming a bad inverter? If i power down and power back up the symptom repeats.

Any idea what may be wrong.

Thanks.

[selldoor]

Re: DELL 1707FPt Turns on but goes black

perhaps the bulbs shattered during delivery? tell the seller it doesnt work and see what the response is.

could be lots of things wrong - read this by retiredcaps, from post19
https://www.badcaps.net/forum/showthread.php?t=10419

If you still want help please post good clear pictures of the whole chassis, and then 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.

Examples of what is needed
https://www.badcaps.net/forum/attachm...1&d=1290283049

https://www.badcaps.net/forum/attachm...7&d=1280167246

It will be useful if you can say what the supposed fault was and a bit about yourself - skills tools etc.

[dexter4000]

Re: DELL 1707FPt Turns on but goes black

I discovered with a flash light shining on the screen that the image is there so the logic board is powered and working fine. Now the problem is with the inverters for the ccfls for sure since the screen is working.
Its just interesting where the humming noise is coming from.

[selldoor]

Re: DELL 1707FPt Turns on but goes black

I think your secondary windings are as in pic.
Power off meter on ohms2000 check S1>S2 S3>S4 and post results.

These transformers hum slightly when working correctly and moreso when faulty - also if the bulbs/wiring is faulty they hum because there is nothing for them to drive.

Have you spare bulbs or another monitor or laptop broken or otherwise you could use as substitute bulbs.

[dexter4000]

Re: DELL 1707FPt Turns on but goes black

I think your secondary windings are as in pic.
Power off meter on ohms2000 check S1>S2 S3>S4 and post results.

These transformers hum slightly when working correctly and moreso when faulty - also if the bulbs/wiring is faulty they hum because there is nothing for them to drive.

Have you spare bulbs or another monitor or laptop broken or otherwise you could use as substitute bulbs.

S1 > S2 - 460.5 ohms
S3 > S4 - 459.8 ohms

I also took apart the lcd and discovered a broken ccfl tube. Probably thats causing the hum on the inverters since cant power the tubes.
Do you know what wattage are those ccfl tubes? I can then test the inverters with some fluorescent lights i have around.

Thanks.

[selldoor]

Re: DELL 1707FPt Turns on but goes black

Ordinary cfls are no good but you can try this by Budm

https://www.badcaps.net/forum/showthread.php?t=19987