Dell E176FPb 17" LCD No Power!

[mrlooi]

I have a Dell E176FPb 17" lcd manufactured by BenQ. It will not power on i.e. there is no light on the power button. I have taken the panel apart and examined the power inverter board and found that it does not use the common p channel Mosfet C5707 eventhough the circuit board has blank spaces for them?. There are no bulging capacitors, found the 2A 250V pico fuse burned and one of the Bridge Rectifiers faulty. Replaced the fuse, bridge rectifier and 0.22uf 275V capacitors but still could not get it working. Anyone have any experience with this LCD panel or problem? Appreciate if anyone also has the schematics for this model of inverter board.

[mrlooi]

Re: Dell E176FPb 17" LCD No Power!

On checking further I found a TL1451 IC in place of the 4 missing 2C5707 mosfet transistors in the inverter circuit...could this be the problem?

[olivercan]

Re: Dell E176FPb 17" LCD No Power!

please send some picture to see the power supply.

[arneson]

Re: Dell E176FPb 17" LCD No Power!

Cut the light circuit away from its power and see if the machine comes on with video and no back lighting.
You described what sounds like a lightning surge victim.
I see a lot of it in SW Florida.

[mrlooi]

Re: Dell E176FPb 17" LCD No Power!

According to my friend, what happened was one day was he tried turning it on and it wouldn't work, the light on the power button wouldn't on at all and it just seemed to die like that. Wasn't because of lightning or surge because he said that he use a surge protector and never on his computer in a thunderstorm.

Further asking around came out with the suggestion that the SMPS could be a problem but comparison with a similar Benq inverter board using a multimeter didn't show a transformer problem...Could it be... there is a defective NCP1200 power IC, however at the moment can't seem to find this IC in the shops around my neighbourhood...can the IC3842 or SG6841D be a suitable replacement?

Finally, another friend indicated that the TL1451 is an inverter IC and will not cause no power symptom unless in rare cases, it is totally shorted. Will put up pictures of the inverter board asap...

[mrlooi]

Re: Dell E176FPb 17" LCD No Power!

please send some picture to see the power supply.

Attached pls. find the pixs of the top and bottom part of the Dell E176FPb inverter board. I also included for comparison a pix of the Benq FP716G+ (which have similar schematics) most of the parts are still intact except for 2 pcs of C5707 and 1 0.22uf 160v capacitor which I have removed earlier.

As mentioned, the 4 C5707 and the 2 P-Channel Mosfet IRFU9024 transistors are missing from the Dell board! Can I confirm that this board doesn't need these transistors to work...or my nagging suspicion the an unscrupulous repairer could have removed them...as I remember my friend brought the LCD to a shop for assessment and quotation on repairs before passing the LCD to me.

[arneson]

Re: Dell E176FPb 17" LCD No Power!

Whats up with Q602 on the bottom of board?
Appears to exploded.

[mrlooi]

Re: Dell E176FPb 17" LCD No Power!

Whats up with Q602 on the bottom of board?
Appears to exploded.

Actually...the Dell board is the white one..while the brown board is Benq...if you are talking about Q601 (I don't see any Q602), I forgot to inform that I removed it for checking purpose.

Pls. focus attention on the first 2 pictures attached, which is from the Dell power board, while the 3rd pix from Benq (Brown color) is only for comparison purposes...

[arneson]

Re: Dell E176FPb 17" LCD No Power!

No I meant transistor Q602.
Unless I'm seeing it wrong, there is only one third of it left intact.
It's sitting right next to 603 at lower left corner.

[mrlooi]

Re: Dell E176FPb 17" LCD No Power!

No I meant transistor Q602.
Unless I'm seeing it wrong, there is only one third of it left intact.
It's sitting right next to 603 at lower left corner.

Thanks for your alert.
Nearly missed it...since it is so small.
Any idea on the code for this SMD transistor Q602, which is located on the bottom of the circuit board (green color) or a similar one normally used for Dell 17 inch Lcds by Benq?

[mrlooi]

Re: Dell E176FPb 17" LCD No Power!

I have identified Q602 with marking W06 and Q603 with marking W04. Further checks indicated that SMD transistor W06 is PMBS3906, a PNP 40V 100ma general purpose PNP transistor manufactured by Phillips. The same is for W04, which is actually PMBS3904.

My problem is where to buy such SMD transistors as its not available here. Just wondering whether I can substitute W06 with 2SA812 and W04 with BC307 transistors. Any suggestions out there?...

[arneson]

Re: Dell E176FPb 17" LCD No Power!

A matching general purpose may bring you back to life if you carefully check any Zeners in that area.
Looks more and more like a surge victim.

[mrlooi]

Re: Dell E176FPb 17" LCD No Power!

A matching general purpose may bring you back to life if you carefully check any Zeners in that area.
Looks more and more like a surge victim.

Thanks for the suggestion...will just do that asap...in the meantime I have identified equivalent transistors for SMD W06 = 2N3906 & W04 = 2N3904...

[eddcs]

Re: Dell E176FPb 17" LCD No Power!

I got this lcd with the IC701 at the bottom of the board damage , it seems melted or something . so anyone here know where can I buy this IC701 chip and how much ? What else could damage if this chip is damage ?

Thanks for answering my question in advance

[mbates14]

Re: Dell E176FPb 17" LCD No Power!

Thanks for the suggestion...will just do that asap...in the meantime I have identified equivalent transistors for SMD W06 = 2N3906 & W04 = 2N3904...

since those 2 transistors are damaged, your power transistor Q601 likely is too. What you need to do, is test each and every single SMD transistor/diode, and your power transistor in that circuit for shorts.

Also, you need to check your secondary output diodes as well... they can short and blow the SNOT out of the driver primary.

Also, R624 looks like she smoked, all the more reason to check EVERYTHING.

[Bobdee]

Re: Dell E176FPb 17" LCD No Power!

I got this lcd with the IC701 at the bottom of the board damage , it seems melted or something . so anyone here know where can I buy this IC701 chip and how much ? What else could damage if this chip is damage ?

Thanks for answering my question in advance

You need to find datasheet for IC701 first, by the markings on the surface of it
If they are no longer vissible then I suggest you ask MRLOOI to have a look at his while he has his monitor appart, he could give you the numbers and letters off his

[pandekripa]

Re: Dell E176FPb 17" LCD No Power!

Dell 17 inch E176fpb has your power PCB and the IC u asked is 1200AP40
and if u know any thing regarding zd602 and zd 601 please share

pandey

[soul12.0]

Re: Dell E176FPb 17" LCD No Power!

im having the same symptoms with my monitor as well. Q603 and Q604 are fried. but there isn't anything else that appears to be fried on the board. any ideas?

[M16Hacker]

Re: Dell E176FPb 17" LCD No Power!

Do you know the Amps and Voltage rating of F601 fuse?

[stj]

Re: Dell E176FPb 17" LCD No Power!

is it not marked?