Dell 1707FPc - 2 Seconds to Black

[smalltownguy]

Picked this up from the body shop at my job at an auto dealership. Very dusty atmosphere; lots of dust had made its way into the PCB.

Monitor powers up for 2 seconds, then goes black. Edit: Image IS viewable with a flashlight.

I opened the case, removed the inverter board, and re-flowed the solder on the inverter transformers, and checked caps. No bulges.

Next I unplugged 3 out of the 4 lamps, testing one lamp at a time. I get the same 2 seconds to black behavior with 3 out of the 4. One of them won't light at all.

I suspect that I have a failed CCFL? Before I crack the LCD open to examine the CCFL in question, is there anything else I should be concerned with?

[alexanna]

Re: Dell 1707FPc - 2 Seconds to Black

Picked this up from the body shop at my job at an auto dealership. Very dusty atmosphere; lots of dust had made its way into the PCB.

Monitor powers up for 2 seconds, then goes black. Edit: Image IS viewable with a flashlight.

I opened the case, removed the inverter board, and re-flowed the solder on the inverter transformers, and checked caps. No bulges.

Next I unplugged 3 out of the 4 lamps, testing one lamp at a time. I get the same 2 seconds to black behavior with 3 out of the 4. One of them won't light at all.

I suspect that I have a failed CCFL? Before I crack the LCD open to examine the CCFL in question, is there anything else I should be concerned with?

Some inverters are dependent on having 2 ccfls hooked up to complete a circuit.
The fact that you have 1 ccfl that does not light may suggest a problem; Try the ccfl that will not light in the other sockets, See if it will light in any of the others.

[Rtech]

Re: Dell 1707FPc - 2 Seconds to Black

Don't get confused, All 4 lamp sockets..ie 2 complete CCFL assemblies,must be plugged in, for the Monitor to work properly,IF IT CAN.So as I imagine you have not got a good test lamp assembly,all you can really do is change both the lamp assemblies over from one pair of sockets to the other pair, and then compare the results.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

This monitor has a sister at the dealership, same model. So I will bring her home and start swapping parts to see where the program migrates. In the mean time, I'll try plugging the suspect CCFL into a different socket and see if it will fire.

[jetadm123]

Re: Dell 1707FPc - 2 Seconds to Black

This monitor has a sister at the dealership, same model. So I will bring her home and start swapping parts to see where the program migrates. In the mean time, I'll try plugging the suspect CCFL into a different socket and see if it will fire.

If you can post (NOT inline, but use "manage attachments") some nice clear photos, of the entire power board top and bottom, it will allow members to see what you're seeing and suggest what to check.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

I brought the sister of this monitor to the test bench tonight.

I unplugged the suspect CCFL from the dead monitor and plugged in a good one from the working monitor.

She fired right up, all 4 sockets illuminating 3 in the dead monitor, and 1 CCFL in the working one.

So, I'm 99% sure that the issue here is a broken/cracked/bad CCFL. Looks like I'll be taking the screen apart on this one to repair it.

I've attached a picture of the top of the inverter board for reference purposes, though I've already tested it in both monitors and it's working just fine in both monitors.

I'll report back once I crack open the screen on this one.

[Ritalin]

Re: Dell 1707FPc - 2 Seconds to Black

Picked this up from the body shop at my job at an auto dealership. Very dusty atmosphere; lots of dust had made its way into the PCB.

Monitor powers up for 2 seconds, then goes black. Edit: Image IS viewable with a flashlight.

I opened the case, removed the inverter board, and re-flowed the solder on the inverter transformers, and checked caps. No bulges.

Next I unplugged 3 out of the 4 lamps, testing one lamp at a time. I get the same 2 seconds to black behavior with 3 out of the 4. One of them won't light at all.

I suspect that I have a failed CCFL? Before I crack the LCD open to examine the CCFL in question, is there anything else I should be concerned with?

Keep in mind just cause they're not bulging doesn't mean they're not bad. I had a few Dell monitors like this where people keep the brightness to 100% and dried up the capacitors. Most common solutions that I've run into is just capacitors and cold soldering, nothing else more complicated than that (knock on wood).

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

Keep in mind just cause they're not bulging doesn't mean they're not bad. I had a few Dell monitors like this where people keep the brightness to 100% and dried up the capacitors. Most common solutions that I've run into is just capacitors and cold soldering, nothing else more complicated than that (knock on wood).

Oh, I'm not opposed to swapping caps if I have to. It's just that in this case the issue seems be a failed CCFL. The monitor wasn't too tough to decase, so if I need to go back in later to replace a few caps that stray out of value, I'm not worried. But no need to fix things that aren't broke for now

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

I took apart the LCD tonight, and look what I found:



Well, that confirms that. Looks like it's off to ccfl warehouse I go.

[retiredcaps]

Re: Dell 1707FPc - 2 Seconds to Black

Good job on finding the problem.

For future reference, please post pictures here using the manage attachments button and please do not post inline. Thanks.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

Understood. Because this picture showed detail that was tough to see unless it was viewed in a larger format, I chose to hotlink it. But to preserve the image for the thread in case photobucket ever goes down....

Image attached.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

Replacement lamp assembly arrived today. CCFL warehouse was quick to ship, and did a good job packaging the item.

Putting the replacement CCFL assembly in wasn't too tough. Hardest part about the whole job was that my display wasn't very user friendly to open. I've opened displays before that had an aluminum 'channel' that you could slide out once you removed one screw at the end of the lamp assembly. Not so with this one - I had to take apart the whole display. Unfortunately there's just no where to go with an LCD glass once it's off to keep dust off of it. I tried to keep as much dust away as possible, but one or two flakes still got in. There's also a slight cloud of moisture trapped in the panel now, but I have a feeling that'll burn off after a few hours. Otherwise she looks good!

Hooray! One repaired monitor.

Total cost: $29.95 in parts, and about 3 hours of labor (including internet research, and diagnosis.)

[retiredcaps]

Re: Dell 1707FPc - 2 Seconds to Black

Understood

Good job on the repair.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

Sorry about that -- post fixed

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

This one landed on my bench again this week. Looks like the caps have finally dried up enough to cause problems. User tells me that he can use the monitor for a while, then it will go dim and he can sometimes get it back on by cycling the power a few times, but usually once the problem begins, it cannot be stopped without leaving the monitor off for several hours.

Sounds like bad caps to me.

Since Christmas is right around the corner and I have an ESR meter on my list, I'll wait a few days to begin troubleshooting this one again. It'll be a good project to test my new meter on. Let's hope that Santa thinks I've been good this year.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

Got my ESR meter for christmas, and all the caps on the inverter board check out OK on this model.

I also brought home a matching monitor from work and began swapping in CCFL's to the good monitor to see if one of them causes problems.

I believe I've narrowed the issue down to one problematic CCFL. With this particular bulb, it fires up with a red tint (presumably not fully lit) and slowly, over the course of about 15 seconds, turns the screen from a red tint to a white tint, signifying that the bulb is fully lit. It also flickers.

I tried hooking the monitor up to a signal to see if I could get the bulb to flicker enough to go out, which is what the original symptom was described as, but I could not repeat the problem. I ran out of time.

I will do some more testing tonight to see if I can reproduce the problem.

[retiredcaps]

Re: Dell 1707FPc - 2 Seconds to Black

it fires up with a red tint

A red or pink tint indicates the bulb is near the final stages of death.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

A red or pink tint indicates the bulb is near the final stages of death.

Thanks for that - it's what I suspect too.

Who knows where the least expensive place is to get just a bare bulb? I'm not opposed to spending $25 on a CCFL assembly for this monitor again if I have to, but if I can get just a bulb in my hands for under $10, I'll go that route.

[retiredcaps]

Re: Dell 1707FPc - 2 Seconds to Black

Who knows where the least expensive place is to get just a bare bulb?

Try ccflwarehouse.com, ccfldirect.com, and/or ebay. Check out the clearance/surplus section in the first two.

[smalltownguy]

Re: Dell 1707FPc - 2 Seconds to Black

The full harnessed assembly for my monitor is on sale for $19.99, so I chose to go that route. I'll report back when I get the parts.