Please help with a Dell E151FPb LCD Monitor

[lightsunglasses]

I have this monitor that when turned on will flash its green power light but no picture whatsoever. The other thing is that it will sometimes work if I hit it. I have heard that this could be an issue with the circuit board's capacitors.

But I have opened the unit and checked the circuit boards and all of the capacitors seem fine; none bulging or discolored. What can I do?

[budm]

Re: Please help with a Dell E151FPb LCD Monitor

Which board version do you have? Post good pictures using attachment.
The board is known for poor solder joints around the inverter transformers and the transistors.
http://s807.photobucket.com/albums/y...INVERTER%20BD/

[lightsunglasses]

Re: Please help with a Dell E151FPb LCD Monitor

I'm not sure how to find the board version but here is what it looks like.

[Rtech]

Re: Please help with a Dell E151FPb LCD Monitor

You can see 2 pairs of small white capacitors on the right hand side of your photo, in fron of the inverter transformers.ech of these pairs have 2 transistors around them.You will probably find that one pair of those have gone short circuit,and will need changing, and the transformers etc need resoldering.

[lightsunglasses]

Re: Please help with a Dell E151FPb LCD Monitor

The 2 small white capacitors, transistors, and transformers and their solders all look okay; but I'll go ahead and try re-soldering them.

[selldoor]

Re: Please help with a Dell E151FPb LCD Monitor

"Look OK" - have you tested them?

[Lumberjack777]

Re: Please help with a Dell E151FPb LCD Monitor

The 2 small white capacitors, transistors, and transformers and their solders all look okay; but I'll go ahead and try re-soldering them.

This is a fairly common board. It's a Ben-Q variation. The C5707's are often shorted. at least one (circled in red)

They have repair kits on eBay for this board. http://www.ebay.com/sch/i.html?_odkw...c5707&_sacat=0

You want to replace the C5707's circled in red. Check the picofuse and replace if needed (circled green). And once I had the other transistor shorted. (2 - circled in blue)
Just make sure to resolder the inverter transformer legs or it'll take out a transistor again.

~L-J-7~

[lestr]

Re: Please help with a Dell E151FPb LCD Monitor

I have this monitor that when turned on will flash its green power light but no picture whatsoever. The other thing is that it will sometimes work if I hit it. I have heard that this could be an issue with the circuit board's capacitors.

But I have opened the unit and checked the circuit boards and all of the capacitors seem fine; none bulging or discolored. What can I do?

To check the caps you need an ESR meter and a capacitance meter. Capacitors may look like new and still be defective. The ESR may be used with the caps on the board so you should be able to determine fairly quickly which ones need to be replaced about 90% of the time. For those that are questionable, use the capacitance tester to find out if present capacitance is within tolerance of rated cap value. Good luck and good trouble shooting!

[lestr]

Re: Please help with a Dell E151FPb LCD Monitor

The 2 small white capacitors, transistors, and transformers and their solders all look okay; but I'll go ahead and try re-soldering them.

As with capacitors and as selldoor says, you can't go by looks. You have to test components properly or you'll spend a lot of time looking in the wrong places. A very nice procedure has been written by retiredcaps in this forum (find it using t=18301) in the discussion for an E152FPb monitor with the same issue, and similar build, as yours. Apparently since the power led is on, there may be no issues with the power supply and the problem is in the inverter section or the main board. So the first thing to do in this case is to make sure the inverter IC is getting power. Simply put: no power to the IC, no picture. Looking at the photo in your post, I believe this is the 16 point IC directly and 0.7 of the way down from the power receptacle on the board. The IC used on the E152FPb is part no. TL1451ACN but you can check your board to see what part is used and from the datasheet find the VCC and GRD pins to measure voltage between these two points. Typically, it's 12 to 14 vDC. What are you getting?
Also, there is a good video on youtube at
www.youtube.com/watch?v=N_wbk2F_syg
that shows how an ESR meter weeds out bad caps.