Dell 2005FPW works for hours, but on hot re-boot fails...

[kingofcoins]

I thought I had fixed this Dell 20005FPW LCD monitor, which originally had the common diode blink and no display. The 1st time in I replaced several s^m young caps on power side though absolutely nothing on board looked bad or overheated. A day or 2 later I did a hot reboot and lcd failed to come on...it just gives a subdued back light pulsing flash every second or so. Next time in I also followed this thread...

https://www.badcaps.net/forum/showth...ghlight=2005fpw

...and did about all mentioned including replacing cap c637, and C635 on the video side. Symptom remains that unit will work fine for say 3, 4, 5 hours or longer, but if you shut down and try a reboot before unit cools for some hours, it will just sit there with a white flash blink and the power on/off button does not function at that time. If I wait and boot the next day, viola it works for hours until you shut down again. It blinks when power is applied not video cable, so I'm sure its PS related.
What do you think is next to do?

[sceva]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

I am having a similar problem with a Dell E176FPf. I replaced some caps, resoldered several connections, but nothing seems to have helped. This monitor will come one, work well for 15 minutes to a couple of hours, then the display will flash on/off about once a second. It shows "Dell" on the screen when it is in the on cycle, not the computer image that was being displayed before the cycle began. The power led also flashes on/off with the display, and the power button has no effect. It will continue to flash until I remove the power cord. Once I reconnected the power cord a few minutes later and this time it just gave a very brief flash, no power led or anything else...

Here are the pics of the board:

[PlainBill]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

I am having a similar problem with a Dell E176FPf. I replaced some caps, resoldered several connections, but nothing seems to have helped. This monitor will come one, work well for 15 minutes to a couple of hours, then the display will flash on/off about once a second. It shows "Dell" on the screen when it is in the on cycle, not the computer image that was being displayed before the cycle began. The power led also flashes on/off with the display, and the power button has no effect. It will continue to flash until I remove the power cord. Once I reconnected the power cord a few minutes later and this time it just gave a very brief flash, no power led or anything else...

Here are the pics of the board:

(Sigh) It doesn't cost anything to open a new thread. For future reference, don't hijack a thread for a different model monitor with a different problem.

Second, troubleshooting by remote control is very much garbage in, garbage out. It would be of a moderate help to indicate which caps were replaced and what the replacements were.

Now for the good stuff. The symptoms suggest the video processor (the Genesis chip at the right side of the board) is being reset. This MAY be due to power supply fluctuations.

I've marked three voltage regulators (I think) with the numbers 1, 2, and 3. What are the part numbers of these three regulators? If you can locate the datasheets for them, you can anticipate my next question by telling me what the output voltages are when the monitor is working, and when it fails.

PlainBill

[kingofcoins]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

So Bill, what of my 2005FPW...yep, I am typing with it...I replaced all the s^m young caps on power supply from 470uf to 1000uf (C201 thru C205),and both C635 and C637 on the video side which were 470uf x 16V. I use panasonic or nichicons low esr's of the same uf or one up, and meet the voltage and often one level up. No I don't have schematic.
Here is the other thread I followed here...try this link:

https://www.badcaps.net/forum/showth...hlight=2005fpw

What do you need to know next on this one that works until you shut down?

Thanks

[PlainBill]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

So Bill, what of my 2005FPW...yep, I am typing with it...I replaced all the s^m young caps on power supply from 470uf to 1000uf (C201 thru C205),and both C635 and C637 on the video side which were 470uf x 16V. I use panasonic or nichicons low esr's of the same uf or one up, and meet the voltage and often one level up. No I don't have schematic.
Here is the other thread I followed here...try this link:

https://www.badcaps.net/forum/showth...hlight=2005fpw

What do you need to know next on this one that works until you shut down?

Thanks

I'm glad to see you used good quality caps as replacements. That's one less possibility.

As far as help for you, well, I'm old and cranky. I will do a lot to help someone get his monitor up and working. But I won't jump to another thread to look at pictures of a monitor that had a different problem.

So, pictures, and indicate the capacitors you replaced. A prime suspect in power supply issues are the small caps around the SMPS controller. To my sorrow, I learned the hard way that they can fail without any visible sign.

PlainBill

[sceva]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Sorry about the hijack. Do you want me to create a new thread and move the post there?

Thanks for the reply, I will check into it and get back.

[PlainBill]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Sorry about the hijack. Do you want me to create a new thread and move the post there?

Thanks for the reply, I will check into it and get back.

It's up to you, but I already misinterpreted kingofcoins' response as coming from you. (Almost made an idiot of myself lashing out at him for a non-response.)

When I am faced with a non-working monitor I do a search by model number.Trying to separate responses to two different monitors with two different problems seriously limits the usefulness of the thread.

PlainBill

[sceva]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

I moved the info to a new post, but can't figure out how to delete my posts in this thread... I will try your suggestions in a couple of days and get back...

[kingofcoins]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Bill...OK, here's the power supply board pics for my 2005FPW. It took over 3 hours up today and two cold boots to get unit to fail on a hot restart. The red area shows the caps I replaced.
Which are the caps near the SMPS controller you mentioned.?

[kingofcoins]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Better full pics...

[PlainBill]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Better full pics...

There are two caps circled in blue. One of them provides stable power for the SMPS controller at startup, the other while it is operating. NOW, this is somewhat of a long shot, but if either of them is bad, the power supply won't come up.

There are two approaches. One is to replace these caps and see if that fixes the problem.

The other is to check if the power supply comes up. If you look at the bottom of the board you will see that the pins for the connector to the logic board has the function of each pin labeled. With the monitor in 'won't restart' condition, check the voltages from the 12V and 5V pins to Gnd. If these are the same in both working and won't work states, the problem is on the logic card, which is a much more difficult matter.

PlainBill

[kingofcoins]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Thanks for sticking with me Bill...the caps you circled are 47uf x 25v 's. The smallest new caps I have on hand are 200uf's. As a quick test replacement trial, I have some computer PSUs and some older Mobos I can salvage from...what would be an acceptable range of values to use...considering I will try for a 'good' brand ? Of course this is temporary, and I maybe buying more parts as well.
In your pic you circled a cap chip in yellow...any significance ?

[PlainBill]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Thanks for sticking with me Bill...the caps you circled are 47uf x 25v 's. The smallest new caps I have on hand are 200uf's. As a quick test replacement trial, I have some computer PSUs and some older Mobos I can salvage from...what would be an acceptable range of values to use...considering I will try for a 'good' brand ? Of course this is temporary, and I maybe buying more parts as well.
In your pic you circled a cap chip in yellow...any significance ?

Since you don't have appropriate caps on hand, perhaps checking if the power supply is at fault (the second option I mentioned above) might be easier. I would guess that something in the 22uF - 100 uF would work. Checking the app note for the SMPS controller might give more information.

That yellow circle was a mistake (yes, not only do I make them, I admit it. Strange, huh?). I had suspected there might be a cap under the glue. When I looked at the bottom of the board I realized it was a ceramic cap. The exercise for the student is to determine how I was able to discern that from the bottom of the board.

PlainBill

[Toasty]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Seems to be a case of not replacing every cap the first time around. Except for the really big one, you most likely should have replaced -all- the others with vent marks. You didn't mention if you tested them for failure or weakness, so it was purely a guess, I suppose?

If you leave it run without power-off or system reboot, does it stay on?

[kingofcoins]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

Bill... I'll try to check if the power supply is at fault.

Quiz answer...You knew the cap type because ceramic caps have a plain (flat chip) symbol thus,... -l l- while electrolytics have a curve (in a can) symbol as -) l-....also because I have a good camera and you have good intuitive skills !

Toasty... Thanks for joining in...the reasons why I didn't replace all the caps first was I didn't have any smalls, and the initial 'fix' worked. I will try a 100uf small temp fix on C103 and C107 next and report as well.

And on your question: "If you leave it run without power-off or system reboot, does it stay on?"....Yes it runs as long as my test uses have been, about 6-7 hours I'd guess, and no it has never failed yet unless I power off or re-boot.

[kingofcoins]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

I salvaged some small caps from a computer PSU to try as temps...yes,yes you folks have got me interested enough in these repairs that I will need to buy an ESR meter.
In the meantime does anyone want to hazard a guess which 2 caps I could try to replace my questionable 1uf x 50v and a 47uf x 25v, the C107 and C103 caps?

My candidates...all are on the bad list, apparently mfg about 2003...

Jun Fu HK 1uf x 50v
G-Luxon SM 2.2uf x 50v
Canicon TC 10uf x 50v
Capxon KM 22uf x 50v
YEC 85*C 47uf x 25v
Canicon TC 47uf x 50v

[kingofcoins]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

UPDATE.....
I chose to use the G-Luxon SM 2.2uf and the Canicon TC 47uf as a trial replacement for those two small caps near the power controller...and viola... it works...so far on a long time yeterday and again today with no hot boot or re-boot failures ! Sucess...>
On this 2005FPW is there any other checks/replacements you think I should make?
So now I'll need to order fresh caps from Digi-key...what sizes would you recommend for my original 1uf x 50v and 47uf x 25 v ? I usually don't stock too many below 220uf for LCD repair works...what sizes do you usually keep below 220 uf ?
Thanks all !
Dan

[PlainBill]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

UPDATE.....
I chose to use the G-Luxon SM 2.2uf and the Canicon TC 47uf as a trial replacement for those two small caps near the power controller...and viola... it works...so far on a long time yeterday and again today with no hot boot or re-boot failures ! Sucess...>
On this 2005FPW is there any other checks/replacements you think I should make?
So now I'll need to order fresh caps from Digi-key...what sizes would you recommend for my original 1uf x 50v and 47uf x 25 v ? I usually don't stock too many below 220uf for LCD repair works...what sizes do you usually keep below 220 uf ?
Thanks all !
Dan

My practice is to order at least 10 of any cap of 100uF or smaller I require, then keep the surplus on hand. They are inexpensive, but can cause unusual problems if they fail.

PlainBill

[995sunglasses]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

I had this same problem with my dell 2005fpw,

I went to radio shack (RS) to buy the capacitors and they gave me the Axial lead ones instead of the radial lead ones which I know doesn't matter but on the 47uF 35v the RS item number they gave me was 272-1015 now I know most of you don't recommend buying from RS but I had to try and fix this thing quick. I noticed on the 47uF/50v one they gave me, the front of that package said 50WVDC maximum and on the capacitor itself gives a temp rating of -40 to 85' C. Is this correct? because on the package of the 1uF 50v capacitor (item number 272-0996) the package says 50v on the back and not 50WVDC like the other one did.

On the 47uF/35v did I buy the right one according to the fix that KINGOFCOINS did?

or my question is, is there a difference between "v" and "wvdc", this is my first time repairing my monitor.

[retiredcaps]

Re: Dell 2005FPW works for hours, but on hot re-boot fails...

I know most of you don't recommend buying from RS

If you live in the USA (which I assume because of the Radio Shack), digikey.com has low cost $2.75 shipping and you get your parts in about 48 hours.

RadioShack does not sell low ESR caps. The fact that you got 85C caps demonstrates this.

Fixing it quick and fixing it correctly are worlds apart.