Dell E178FPb - white screen

[PlainBill]

This monitor was a Craigslist freebie. The previous owner said it had been purchased with several others, then set aside as a spare. When he tried it after more than a year all he blank screen. Testing it, I get is a green power button and a white screen. After about 30 seconds the power button goes to orange and the screen goes black. The power button seems to function normally. With or without signal makes no difference, except the power button never goes orange.

Opening it up, I verified all connectors seemed to be firmly plugged in, so I tried checking the fuse on the panel electronics board. That is good. I have checked all caps on the power supply and the logic card, all low esr caps are well within specs. The power supply is putting out 5 volts. While checking the LCD electronics, I checked voltages at the test points. Power is present, but I don't have a clue as to the appropriate voltages, nor do I know for certain the logic board is working.

Any suggestions before I drag a scope out? Or sell it on eBay? Note the massive heat sinks in the power supply. Oh, and any clues on who made this?

PlainBill

[EGuevarae]

Re: Dell E178FPb - white screen

This monitor was a Craigslist freebie. The previous owner said it had been purchased with several others, then set aside as a spare. When he tried it after more than a year all he blank screen. Testing it, I get is a green power button and a white screen. After about 30 seconds the power button goes to orange and the screen goes black. The power button seems to function normally. With or without signal makes no difference, except the power button never goes orange.

Opening it up, I verified all connectors seemed to be firmly plugged in, so I tried checking the fuse on the panel electronics board. That is good. I have checked all caps on the power supply and the logic card, all low esr caps are well within specs. The power supply is putting out 5 volts. While checking the LCD electronics, I checked voltages at the test points. Power is present, but I don't have a clue as to the appropriate voltages, nor do I know for certain the logic board is working.

Any suggestions before I drag a scope out? Or sell it on eBay? Note the massive heat sinks in the power supply. Oh, and any clues on who made this?

PlainBill

What screen does it have (panel)? AUO, Chimei, Samsung? Maybe I have a spare one to give you.

[Wizard]

Re: Dell E178FPb - white screen

this is amazing that this failed still brand new.

Check the capacitors on the mainboard? Same with the PSU caps. And I agree with you on pathetic PSU heatsink.

Cheers, Wizard

[lucky13]

Re: Dell E178FPb - white screen

A Note the massive heat sinks in the power supply.
PlainBill

Massive! LOL

Delta makes a lot of these p/s for monitors. This is the most massive I've ever seen!

With or without signal makes no difference, except the power button never goes orange.

PlainBill

If the power button never goes orange w/o a signal, then the main/logic board (one with that Genesis chip) is not working.

You probably have to check those caps & regulator ICs on that board near the power connector. One likely for 3.3v and the other for 2.5V or 1.8V.

[Wizard]

Re: Dell E178FPb - white screen

Going orange without signal is normal, it should stay green or whatever it is in for power light with signal present.

Cheers, Wizard

[PlainBill]

Re: Dell E178FPb - white screen

Panel is made by Chunghwa.

Behavior of power button:

Without signal present: Plug into outlet. Power button goes green. Screen lights up solid white. After about 30 seconds the power button goes orange, screen goes dark. Push power button, power button goes dark. Push power button again, power button goes green, screen goes white. After 30 seconds, power button goes orange, screen goes dark.

With signal present the power button never goes orange, all other actions remain the same. Other than the solid white screen, this is the type of activity I would expect to see on a properly working monitor.

Power supply board has 2 1000uF 10V Nichicon PW(M) caps in parallel for the 5.1 Volt supply, 2 680uF 25V Nichicon HD(M) caps in parallel for the inverter. I did not remove them from the board, but the ESR was less than .05 for each pair. This is in the range where wiggling a probe will change the reading.

There is also a pair of 470uF 25V Capxon GLs in the inverter. I didn't bother testing those.

The logic board is a little more complex. It has 11 capacitors in five groups.

Group 1 was a 330uF 16V Teapo SC with an ESR of .06
Group 2 was a 22uF 25V Luxon SM with an ESR of 1.1
Group 3 was a 330uF 16V Teapo SC in parallel with a 22uF 25V Luxon SM, the pair had an ESR of .06
Group 4 was four 22uF 25V Luxon SM in parallel, the group had an ESR of .40
Group 5 was a 100uF 25V Teapo SC in parallel with two 22uF 25V Luxon SM, the group had an ESR of .30

There appear to be two voltage regulators on the logic board. I have not tried to measure the voltage out of each. I have been unable to find a data sheet for the Gemini chip that gives it's power supply voltages.

PlainBill

[PlainBill]

Re: Dell E178FPb - white screen

What screen does it have (panel)? AUO, Chimei, Samsung? Maybe I have a spare one to give you.

Panel is made by Chunghwa. Testing with a known good panel will tell me where to look. I don't mind replacing all the caps on the boards, but I'm not going to do that until I have confidence it's not the panel.

Bill

[Nama]

Re: Dell E178FPb - white screen

I fixed 2 of those this week. neither had the same problem as yours Bill. I may also have a spare Main board for that model. I had a few with cracked screens. If I find it I will send it no charge. I'll post back If I find it. Jacob

[PlainBill]

Re: Dell E178FPb - white screen

I fixed 2 of those this week. neither had the same problem as yours Bill. I may also have a spare Main board for that model. I had a few with cracked screens. If I find it I will send it no charge. I'll post back If I find it. Jacob

Thanks, I'm looking forward to it.

Bill

[EGuevarae]

Re: Dell E178FPb - white screen

Panel is made by Chunghwa. Testing with a known good panel will tell me where to look. I don't mind replacing all the caps on the boards, but I'm not going to do that until I have confidence it's not the panel.

Bill

No luck. I have 15" and 19" Chung Hwa panels, not 17". Looking at my notes, I had three Hanns-G 171D with that same problem, and the three panesl were dead. I still have one complete panel, another gave the CCFLs for another unit, and one was fixed with a panel from another unit. But the constant there was the gm chip and the white screens. Fuse on panel was right on the three panels I had and yet only white screen. I tested the three VBoards with the good panel and they are OK. My panes were bad. I guess yours is too

[Nama]

Re: Dell E178FPb - white screen

OK bill. I found your board. Would you like the inverter also?. PM or email me your address. I'll send it out asap. Jacob

[PlainBill]

Re: Dell E178FPb - white screen

To clarify details on the panel, I've taken a few more pictures. I've discovered a tripod makes doing that so much easier!!

Working on the LCD panel electronics board doesn't look to bad - provided you enjoy soldering with a tip the size of a sewing needle and using a microscope to view the components.

PlainBill

[Nama]

Re: Dell E178FPb - white screen

Your package is in the mail Bill. I just sent you the whole monitor without the stand. Jacob

[cjmclellen]

Re: Dell E178FPb - white screen

In my experience, the white screen is an indication that the panel is not receiving a signal. And this is usually caused by a blown SMD fuse located on the panels PCB, near the input connection. I've even just blobbed some solder over the bad fuse to make the circuit again. This is not politically correct, but neither am I!!!

[PlainBill]

Re: Dell E178FPb - white screen

In my experience, the white screen is an indication that the panel is not receiving a signal. And this is usually caused by a blown SMD fuse located on the panels PCB, near the input connection. I've even just blobbed some solder over the bad fuse to make the circuit again. This is not politically correct, but neither am I!!!

This is an unusual case. As noted in the first post, I already checked the smd fuse on the panel electronics and it is good.

PlainBill

[cjmclellen]

Re: Dell E178FPb - white screen

Sorry. I was confident that the SMD fuse was the issue here, and merely skimmed through the preceeding entries looking for something saying that it had already been checked.

I guess I need new eyes...
and a rich girlfriend, and a nice motorcycle, and a good job, and.....
OK, I'll stop now.

Good luck to you!

[PlainBill]

Re: Dell E178FPb - white screen

I got confident today and dragged this out again, together with the oscilloscope. Hook everything together, remove the screws holding the panel circuit card in place, and plug it in.

Look at the front of the panel and I've got the typical Dell test pattern floating across the screen. Grab the probe and sure enough I have voltages at most of the test points. Hot Dawg!!! Grab the DMM and a piece of paper and start to record the voltages. First one is 0 volts???? That was 25 volts a minute ago!!! Check the voltages, all 0 volts except one that is +5.

OK, it's an intermittent. Let's see if I can trace this. That's when I discovered the problem. The parts are so tiny I need a microscope!!!!

PlainBill

[EGuevarae]

Re: Dell E178FPb - white screen

OK, it's an intermittent. Let's see if I can trace this. That's when I discovered the problem. The parts are so tiny I need a microscope!!!!

PlainBill

What about the new eyes?

[PlainBill]

Re: Dell E178FPb - white screen

What about the new eyes?

Eye, singular. It works great from about 4 feet on out. Not what is needed for this job.

I asked for the model Steve Austin had. The insurance company said they would come up with the $45,324 if I came up with the $28,000,000. I agreed to accept modifications to the present eye.

PlainBill

[EGuevarae]

Re: Dell E178FPb - white screen

Eye, singular.

Sorry. I forgot. I tend to talk about "eyes" since I got my glasses.

The insurance company said they would come up with the $45,324 if I came up with the $28,000,000.

.... I agreed to accept modifications to the present eye.

It wa$ a very wi$e deci$ion. I think I would have done the $ame $hould I ever be in that $ituation.