Dell 1703FPs stuck "in power save mode"

[mathog]

Intercepted a Dell 1703FPs on its way to ewaste. It powers on but says

"Analog Input"
In power save mode
Press any key on keyboard or move mouse

The VGA video input is from a KVM, and I can flip it back and forth between this monitor and my usual one, and the computer is definitely not in power save mode, there is an image, but the display thinks it should be in sleep mode. Was able to switch it to "Digital Input", but don't have a signal like that to feed it. Anyway, the backlights work, it doesn't shut itself off, but it looks like it doesn't see any video.

Opened it up (which was slightly challenging since the stand release button was broken) and found that it looked exactly like the one in the thread labeled "Dell 1703fps backlight problem" elsewhere on this forum. No signs of distress, bulging capacitors, burns, or anything like that. Lots of hard component glue though in various places (the stuff that looks like dried hot glue, but opaque). This model has a power board, a video board, and an inverter board. The last two are covered with surface mount components.

I can check the voltages on the power board, and maybe resolder the VGA socket connectors (possible bad connection there), but not sure what else to try. Suggestions? Fixing the video/logic board for anything complicated is likely out of the question, too many itty bitty surface mount components, and no appropriate tools for working on those.

[pedro]

Re: Dell 1703FPs stuck "in power save mode"

Intercepted a Dell 1703FPs on its way to ewaste. It powers on but says

"Analog Input"
In power save mode
Press any key on keyboard or move mouse

The VGA video input is from a KVM, and I can flip it back and forth between this monitor and my usual one, and the computer is definitely not in power save mode, there is an image, but the display thinks it should be in sleep mode. Was able to switch it to "Digital Input", but don't have a signal like that to feed it. Anyway, the backlights work, it doesn't shut itself off, but it looks like it doesn't see any video.

Suggestions? Fixing the video/logic board for anything complicated is likely out of the question, too many itty bitty surface mount components, and no appropriate tools for working on those.

First up, flick the KVM out of there and let us know what it does differently, if anything.

In the monitor the sync signals are (normally) detected by the processor on the video board. KVM's - especially cheap ones - tend to pass a somewhat reduced amplitude signal through to the screen. Some wear this OK, some don't work with the lower p-p amplitude.

When you said

there is an image, but the display thinks it should be in sleep mode.

did you mean that you can see some image on the subject monitor, or just that you know there is video drive to it?

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

First up, flick the KVM out of there and let us know what it does differently, if anything.

Will try that when I get a chance. I suspect this isn't the issue though, rather that the lack of a response to a directly connected video cable led the original owner to put it out for ewaste pickup.

did you mean that you can see some image on the subject monitor, or just that you know there is video drive to it?

I meant that the internally generated video shows up OK. For instance, the color box that wanders around on no signal at first power on is bright and sharp. Similarly the "power save" message is displayed clearly. But no external video ever makes it onto the screen.

[seanc]

Re: Dell 1703FPs stuck "in power save mode"

It won't hurt to try re-soldering the VGA connector. Do you have anything with DVI output? It would be worthwhile testing (borrow a DVI cable) if you can.

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

It won't hurt to try re-soldering the VGA connector. Do you have anything with DVI output? It would be worthwhile testing (borrow a DVI cable) if you can.

Have a video card with DVI out but no DVI cable. Will try to scrounge one up tomorrow. Googled a bit and discovered that most of the "in power save mode" issues with this model revolve around some sort of EDID corruption issue and the DVI port - the VGA usually works even when the DVI is stuck in its power save mode.

Found one interesting tidbit. Look under "Power Management Modes" on this link:

http://support.dell.com/support/edoc...s/en/specs.htm

It says that the analog input power save mode corresponds to the card having both horizontal and vertical sync inactive, and the video blanked. Probably the monitor only checks one of those to see if it should go to sleep, and that could be the bad connector pin.

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

One step forward one step back.

In testing the VGA connector continuity with a paper clip in the holes I noticed that some of the measurements were taking a long time to settle. So the holes were scrubbed out with the paper clip, on the theory that they just might be dirty.

Plugged it back in and a picture came up immediately. That's the step forward.

One second later the backlight turned off, but the power light remained green. That's the step back. The image remained on the LCD and was visible with a flashlight.

I have seen an LCD power off and the power light go to amber, but this is the first one to stay green. There are not very many markings on the boards, but I can see on one connector what is supposed to be +5,+14 and ground. No place to test it easily though. The thing is wired together a bit oddly: the power board sends two connectors to the video board (one with 3 wires, the other with a bunch), and the video board has a cable to the panel ( of course) and another cable (with lots of wires) that goes directly to the inverter, so it must route power to it.

No overt signs of capacitor failure or burnt components, at least, that I have seen yet.

My best guess is that the unit was pulled because the back light was turning off, and sat around for a long time with nothing plugged into the VGA connector, so it got dirty, causing the power save mode message.

[PlainBill]

Re: Dell 1703FPs stuck "in power save mode"

One step forward one step back.

In testing the VGA connector continuity with a paper clip in the holes I noticed that some of the measurements were taking a long time to settle. So the holes were scrubbed out with the paper clip, on the theory that they just might be dirty.

Plugged it back in and a picture came up immediately. That's the step forward.

One second later the backlight turned off, but the power light remained green. That's the step back. The image remained on the LCD and was visible with a flashlight.

I have seen an LCD power off and the power light go to amber, but this is the first one to stay green. There are not very many markings on the boards, but I can see on one connector what is supposed to be +5,+14 and ground. No place to test it easily though. The thing is wired together a bit oddly: the power board sends two connectors to the video board (one with 3 wires, the other with a bunch), and the video board has a cable to the panel ( of course) and another cable (with lots of wires) that goes directly to the inverter, so it must route power to it.

No overt signs of capacitor failure or burnt components, at least, that I have seen yet.

My best guess is that the unit was pulled because the back light was turning off, and sat around for a long time with nothing plugged into the VGA connector, so it got dirty, causing the power save mode message.

Good job of diagnosing the initial problem. Now you have the 'two seconds to black' problem. Search on it here, you will find more than you want to know about the problem, and how to troubleshoot it.

PlainBill

[seanc]

Re: Dell 1703FPs stuck "in power save mode"

I find it odd that the backlight stayed on with no VGA signal, but then it goes out.
When my 1703FP had a 2 seconds to black issue, it was a transformer on the backlight inverter, eventually a hole burned through the side of it - made diagnosis a bit easier.

Anyway, my point being, test the transformers for shorts.

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

With no video cable plugged in and the monitor on measured on the jumper where the PS board indicated 14V and 5V. It measured 19V and 5.1V. Both go to the video card, but perhaps the "14V" isn't used there and is just passed on through the next cable to the inverter, where the 19V might be causing problems. Of course the inverter shuts off before I can measure the voltage, so it might be that it's 19V just because there is no power being used by the inverter. Took out all the boards again and inspected carefully with a magnifying glass, still no overt signs of failure.

Will replace the electrolytic caps on the PS and inverter boards and hope for the best. Couldn't read the brands of any of them in situ, have to wait until they come out to see what they are.

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

Anyway, my point being, test the transformers for shorts.

That better not be it since the only thing not surface mounted on the inverter board is the one electrolytic capacitor. Half the leads on each transformer are under black tar like material. That stuff likes very hard to remove without damaging the leads/board underneath it.

This picture is from another thread, but it looks just like mine.

https://www.badcaps.net/forum/showpo...68&postcount=6

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

Top and bottom of the power supply board.

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

Finally had some time to get back to this display. Swapped PS caps C612,C6132,C613, C609, C610,c611 and the lone inverter cap C1. (Kept the ones I removed - they didn't look bad, but were not a quality brand.) Nothing changed, it powers on, puts up an image (the Dell color bar box as no video input), and 1-2 seconds later goes to black leaving the image on (visible by flashlight) and the power light still green.

Just noticed there is a small 22uF 50V Capxon on the PS board, on the input side of the final transformer. (Not sure how it is wired into the circuit.) It looks OK though.

I know that it's traditional to blame this on the inverter, but the 14V line is still reading 19V on the PS. Sure there's no load, but it seems much too high to me, - are the "14V" PS values normally that poorly regulated on a monitor? The 5V measured on the PS is very close.

[seanc]

Re: Dell 1703FPs stuck "in power save mode"

Try changing that 22uf Capxon too!

[PlainBill]

Re: Dell 1703FPs stuck "in power save mode"

Finally had some time to get back to this display. Swapped PS caps C612,C6132,C613, C609, C610,c611 and the lone inverter cap C1. (Kept the ones I removed - they didn't look bad, but were not a quality brand.) Nothing changed, it powers on, puts up an image (the Dell color bar box as no video input), and 1-2 seconds later goes to black leaving the image on (visible by flashlight) and the power light still green.

Just noticed there is a small 22uF 50V Capxon on the PS board, on the input side of the final transformer. (Not sure how it is wired into the circuit.) It looks OK though.

I know that it's traditional to blame this on the inverter, but the 14V line is still reading 19V on the PS. Sure there's no load, but it seems much too high to me, - are the "14V" PS values normally that poorly regulated on a monitor? The 5V measured on the PS is very close.

The 14 volt supply running at 19 volts would appear to indicate a problem. Here is a quick description of the design of they typical SMPS. The SMPS controller feeds a series of pulses into the transformer. The width of the pulses determine the amount of energy transferred from primary to secondary. The transformer has multiple secondaries. One is used to generate the 5V supply, another to generate the 14V supply. The 5V output feeds an optoisolator, the output of the optoisolator feeds the control input of the SMPS controller. In very simple terms, if the output voltage is too low, the pulses get wider, if it is too high the pulses get narrower. The result is very good regulation of the 5Volt supply.

The actual voltage of the 14 volt supply depends on two things - the load on the 14 volt supply and the load on the 5 volt supply. If the 14 volt supply reads 19 volts with the inverter off, that's interesting, but not a cause for alarm. If it reads 19 volts in the few seconds the inverter is operating, that IS a sign of a problem.

PlainBill

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

The 14 volt supply running at 19 volts would appear to indicate a problem. Here is a quick description of the design of they typical SMPS. The SMPS controller feeds a series of pulses into the transformer. The width of the pulses determine the amount of energy transferred from primary to secondary. The transformer has multiple secondaries. One is used to generate the 5V supply, another to generate the 14V supply. The 5V output feeds an optoisolator, the output of the optoisolator feeds the control input of the SMPS controller. In very simple terms, if the output voltage is too low, the pulses get wider, if it is too high the pulses get narrower. The result is very good regulation of the 5Volt supply.

Which is what is observed - the 5V is very well regulated.

The actual voltage of the 14 volt supply depends on two things - the load on the 14 volt supply and the load on the 5 volt supply. If the 14 volt supply reads 19 volts with the inverter off, that's interesting, but not a cause for alarm. If it reads 19 volts in the few seconds the inverter is operating, that IS a sign of a problem.
PlainBill

It was hard to measure the voltage in the 1-2 seconds when it was on. My recollection was that it was around 17V, but the DMM might not have settled yet.

The inverter could be OK if the lamps are bad, but I don't have a way to test those. Hmm, wait, yes I do, there is a 17" Tyris I was going to recap the video board, and those inverters and lamps work. The CCFL lamp plugs aren't the same though. Will rig something up, play mix and match, and report back. Yet another place where the mythical CCFL test circuit would have been employed!

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

The inverter could be OK if the lamps are bad, but I don't have a way to test those. Hmm, wait, yes I do, there is a 17" Tyris I was going to recap the video board, and those inverters and lamps work. The CCFL lamp plugs aren't the same though. Will rig something up, play mix and match, and report back. Yet another place where the mythical CCFL test circuit would have been employed!

Here are the test results, CN1,CN2 (on the bottom of the Dell inverter, plug side of the monitor), CN4, CN5 (the other side of the inverter, top of the monitor) are the connectors on the Dell inverter, and Dell/Tyris indicate which lamp is plugged in:

 CN1  CN2   CN4   CN5   Tyris Panel Dell Panel
 Tyris Tyris  Tyris  Tyris  Lit       Dark
 Tyris Tyris  Tyris  Dell   Lit       Dark
 Tyris Tyris  Dell   Tyris  Lit       Lit
 Tyris Dell  Tyris  Tyris  Lit       Lit
 Dell  Dell  Tyris  Tyris  Lit       Lit
 Dell  Dell  Dell   Tyris  Lit       Lit

So it turns out the lamp with the blue wire which was plugged into CN5 is bad. If that one lamp is substituted with one from the Tyris the Dell lights and stays on! Not shown, was driving the Dell lamps with the Tyris inverter, which had similar results - plug in the blue wired lamp which was originally plugged into CN5 on the Dell and it shut off the inverter on the Tyris.

This really emphasizes the need for a good way to test the lamps - a bad lamp does make a good inverter appear to be blown. These tests only show that the other 3 lamps in the Dell are "good enough" that the inverters will accept them, but for all I know a couple of them are days away from going over the edge. Or for that matter, all that might be wrong with this bad one is a broken wire in the connector. I measured a good one and the bad one for resistance through the end connector with a DMM, but they were both open, so nothing gained by that exercise. A circuit which would let one test firing voltage and current at sustained voltage on a single CCFL would be a big help here.

[PlainBill]

Re: Dell 1703FPs stuck "in power save mode"

Here are the test results, CN1,CN2 (on the bottom of the Dell inverter, plug side of the monitor), CN4, CN5 (the other side of the inverter, top of the monitor) are the connectors on the Dell inverter, and Dell/Tyris indicate which lamp is plugged in:

 CN1  CN2   CN4   CN5   Tyris Panel Dell Panel
 Tyris Tyris  Tyris  Tyris  Lit       Dark
 Tyris Tyris  Tyris  Dell   Lit       Dark
 Tyris Tyris  Dell   Tyris  Lit       Lit
 Tyris Dell  Tyris  Tyris  Lit       Lit
 Dell  Dell  Tyris  Tyris  Lit       Lit
 Dell  Dell  Dell   Tyris  Lit       Lit

So it turns out the lamp with the blue wire which was plugged into CN5 is bad. If that one lamp is substituted with one from the Tyris the Dell lights and stays on! Not shown, was driving the Dell lamps with the Tyris inverter, which had similar results - plug in the blue wired lamp which was originally plugged into CN5 on the Dell and it shut off the inverter on the Tyris.

This really emphasizes the need for a good way to test the lamps - a bad lamp does make a good inverter appear to be blown. These tests only show that the other 3 lamps in the Dell are "good enough" that the inverters will accept them, but for all I know a couple of them are days away from going over the edge. Or for that matter, all that might be wrong with this bad one is a broken wire in the connector. I measured a good one and the bad one for resistance through the end connector with a DMM, but they were both open, so nothing gained by that exercise. A circuit which would let one test firing voltage and current at sustained voltage on a single CCFL would be a big help here.

Good job of troubleshooting. Now you can check if the 'CN5 CCFL' is bad, or it's merely a bad solder joint or broken wire.

I can sketch circuits which will allow monitoring current and voltage for any inverter / CCFL setup. There are practical problems, however. For one, there are a wide variety of connectors involved, as well as a wide variety of tubes and inverters.

PlainBill

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

I am going to open this panel to check the connectivity on the wires of the bad CCFL, and if that isn't it, install a scavenged CCFL from another 17" Dell. Unfortunately, that other Dell has the wrong type of inverter connector, but those wires can be swapped.

The big question: how does one go about opening one of these panels in order to gain access to the CCFLs? Have been googling, but only found pictures so far of folks opening laptops. The back of this panel is metal and of course the front is glass. I do not recall seeing any screws, but there might be some tiny ones I didn't notice the last time I looked at it.

[retiredcaps]

Re: Dell 1703FPs stuck "in power save mode"

See this youtube video (YMMV)

http://www.youtube.com/watch?v=ZvQdY...eature=related

If you hate techo or whatever that is playing, turn off your speakers. (My favourite line in the movie "UP" is when Mr Fredricksen says to Russell "Now, we're gonna walk to the falls quickly and quietly with no rap music or flashdancing." ROFL)

The big question: how does one go about opening one of these panels in order to gain access to the CCFLs?

[mathog]

Re: Dell 1703FPs stuck "in power save mode"

See this youtube video (YMMV)

http://www.youtube.com/watch?v=ZvQdY...eature=related

Either the girl or the camera is on speed. Anyway, thanks for the link, that helped.