HP 2007W LCD Monitor

[Spork Schivago]

Re: HP 2007W LCD Monitor

The test point you wanted me to measure reads around 5.25V, the regulator reads 5.25V on the one side and 5.25V and 13mV, respectively. The fuse reads 5.25v on the side from the ribbon cable and 0v on the other side.

Do you think that maybe I soldered on a fuse that was too low? Should I try jumping it with a wire? I have some resistors but they're 1/8w - 1/2w. I'd think the 1/8w would maybe be too much. What do you think?

Also, I don't know if this is important or not but the bigger regulator on the corner of the logic board is fairly hot. Hot enough where I can't keep my finger on it for only a couple of seconds.

[budm]

Re: HP 2007W LCD Monitor

1Ohm 1/8w will burn open if overloaded, you need 1 Ohm 1/4w for testing in place of the fuse, the new fuse you put in may be too small. It is good that you did not damaged the switched transistor by keep hooking up shorts circuit to it. At this point, the panel is bad for sure, you may have to Ohm out the output side of that 3.3v regulator to see what it shows, the shorted circuits may be at the out put side of this regulator. So Ohm it out.

[Spork Schivago]

Re: HP 2007W LCD Monitor

K, so I did the 1/4w 1ohm resistor and now we're getting something on the screen. It's a jacked up picture of the background on the PC we have it connected too. Is this because the TCON board is shot like we thought or is there any chance of salvaging it at this point in time? I never thought we'd get this far, honestly....
here's a photo of the display

[budm]

Re: HP 2007W LCD Monitor

That is strange looking screen, do you get 3.3vdc from that IC. I still do not understand why you did not see anything on the screen when you bypass the blown fuse with the meter. The T-CON is shot. We need to find out which component shorted out, but we can only do so far.

[Spork Schivago]

Re: HP 2007W LCD Monitor

Okay. I think there's something wrong with the multimeter and that is why I did not get any reading while we by-passed the fuse. The screen is old but if we tap the side, there's a picture of a blown fuse on the screen. I've ripped it apart and all I can find is the fuse for the 400mA port. Despite the picture on the back of the DMM, there appears to be no 20A / 250V fuse. There's a spare fuse in there but it's just that, a spare.

[Spork Schivago]

Re: HP 2007W LCD Monitor

I did get a 3.3vdc from that regulator on the TCON board. I also checked what I thought was a little regulator on the logic board. Is this broken or is it something else? The other little ones on the logic board seem to measure higher voltages. I'm attaching a picture. Sorry for the crappy job on it, I'm not too skilled at making nice pictures. There's also another regulator on the TCON board opposite side. It's the only other regulator on that board. It seems fine. Reading around 3VDC for the input, 1.7VDC for the middle pin and the output.

Also, on the back of that TCON board, there's a ton of test points with labels on them. Stuff like VCOMX78, YVGG1, BR2P1...You think those could help me in testing this board? Maybe there's some definitions on what they all mean. Got any links?

[retiredcaps]

Re: HP 2007W LCD Monitor

Okay. I think there's something wrong with the multimeter and that is why I did not get any reading while we by-passed the fuse.

One or more of your fuses in the multimeter could be blown through accidental use?

I know on my Fluke 75, I can do the following to test the internal fuses. It may or may not work for you.

1) Put your black probe into the COM jack.
2) Red into the V jack.
3) Put your dial onto Ohms.
4) Take your red probe and put it into the mu/ua jack. It should read less than 2 ohms.
5) Take your red probe and put it into the 20A jack. It should read less than 2 ohms.

Report your findings for 4 and 5. If you get 0L for 4 and 5, it could mean your fuse is blown.

Again, this may not work for you.

[budm]

Re: HP 2007W LCD Monitor

That 3-pin device on the logic board is a transistor, you are reading the Base-Emitter junction voltage which is about 0.6~0.7vdc when it is bias on, so that is normal.
The logic board provide 5VDC for the T-CON by that switched transistor as I indicate earlier, that 5Vdc is generated in the main power supply board and is fed to that transistor, the Controller IC sends the signal to turn on the transistor when the monitor detects the video signal from the PC, or it will go to sleep when the video signal is no longer present, same thing for the backlights this is done to save power.
The 1.7~1.8V you get from another regulator on the T-CON board is probably for the big IC for timing/signal processor of the T-CON board, same as the 3.3v regulator.

[retiredcaps]

Re: HP 2007W LCD Monitor

It seems fine. Reading around 3VDC for the input, 1.7VDC for the middle pin and the output.

The part number on the regulator tells you the correct output voltage. For example, on an AL1117-18, the suffix indicates that 1.8V is the correct voltage.

1.7V is not an usual voltage. It is normally 1.8V. Most voltage regulators have a 1% tolerance.

So

1.8 x 0.99 = 1.782V
1.8 x 1.01 = 1.818V

So anything in between is fine.

(1.8 - 1.7)/1.8 = is 5.5% difference which suggests the voltage regulator is failing "low". You may want to remeasure and confirm.

[budm]

Re: HP 2007W LCD Monitor

Make sure to put meter in a finer scale so you can read at least 2 decimal point, I have a feeling he has it set to high range.

[Spork Schivago]

Re: HP 2007W LCD Monitor

Report your findings for 4 and 5. If you get 0L for 4 and 5, it could mean your fuse is blown.

I get almost 1K for the uA - mA port and 0L for the 20A. I ripped the whole meter apart earlier looking for the 20A fuse and I cannot find anything. Only a fuse for the 400mA port which reads 500mA for the fuse. Maybe it was an efuse or whatever those are called?

She reads 1.81VDC on the middle pin.

That 3-pin device on the logic board is a transistor, you are reading the Base-Emitter junction voltage which is about 0.6~0.7vdc when it is bias on, so that is normal...

I'm starting to understand I believe. I know this has taken up a lot of your guyses time. I've learned so much though since I first started. I've never really understood how the digital electronics stuff worked. I can solder the stuff on and off, but understanding it, that's a whole nother story!

Make sure to put meter in a finer scale so you can read at least 2 decimal point, I have a feeling he has it set to high range.

Okay, I've had it on auto-ranging. The finer scale definitely gives me more accurate readings. Thanks

[budm]

Re: HP 2007W LCD Monitor

You can learn more about transistors here:
http://en.wikipedia.org/wiki/Transistor

Regulator:
http://en.wikipedia.org/wiki/Linear_regulator

CCFL backlights inverter:
http://en.wikipedia.org/wiki/CCFL_inverter

[retiredcaps]

Re: HP 2007W LCD Monitor

I get almost 1K for the uA - mA port and 0L for the 20A. I ripped the whole meter apart earlier looking for the 20A fuse and I cannot find anything.

1K for the uA/mA sounds correct which means your 500ma fuse is okay. Sometimes, there is a 1K resistor in the jack for protection.

On the front of your multimeter, it clearly shows that the 20A is fused. The fuse could be on the other side of the multimeter pcb. However, I don't want you possibly wrecking your multimeter looking for it.

I'll see if I can find your multimeter manual online.

[Spork Schivago]

Re: HP 2007W LCD Monitor

I tested a bunch of points on the back of the board. There's a few labeled something like FR2P1 and then below it FR2N1. There's maybe 12 points like that. I figure the P means positive, the N means negative. All of them tested around 1VDC. I'll do some poking around tomorrow on this but it looks like there isn't much more that can be done. Thanks for all the help and who knows, maybe I'll find something? Night everyone

[selldoor]

Re: HP 2007W LCD Monitor

1K for the uA/mA sounds correct which means your 500ma fuse is okay. Sometimes, there is a 1K resistor in the jack for protection.

On the front of your multimeter, it clearly shows that the 20A is fused. The fuse could be on the other side of the multimeter pcb. However, I don't want you possibly wrecking your multimeter looking for it.

I'll see if I can find your multimeter manual online.

I cant find it but did find this for their current model - fuses might be in the same place? Id have thought they should be reasonably accessible.

[retiredcaps]

Re: HP 2007W LCD Monitor

I cant find it but did find this for their current model - fuses might be in the same place?

I couldn't find the manual either and generally I have been able to find other Craftsman models.

Yes, the fuses could be on the "underside".

[Spork Schivago]

Re: HP 2007W LCD Monitor

Hey guys! Sorry I haven't gotten back to you guys until now. I was in the ER. I was replacing the valve cover gasket on my Jeep. I borrowed some tools from my father, after using them, my hands and part of my arm turned all red and felt like some one poured gas all over it and set it on fire. The docs said it was a chemical burn. It sucks and my hands are all wrapped up now.

Anyway, I ripped apart my multimeter and took out the PCB. You guys were right, there was a fuse in there and it's blown! It looks like a ceramic fuse but instead of being white, it's a darkish gray. I have a white ceramic 250v 10A fuse that I was thinking of using until I can get a 20A one. Worst case is it'll blow if I go over that limit, right?

And even better news! For the longest time, my multimeter screen would go out. Like I could read all the numbers some of the time but other times it was cutting out. I ripped apart the screen part and cleaned everything. There were glass connectors. It was cool. Works like a charm now!

I also found what I believe to be a schematic of my power and logic board that gives voltages and all that jazz. It's for an acer screen though but everything seems to match up. Still looking for one for the TCON board though.

[retiredcaps]

Re: HP 2007W LCD Monitor

The docs said it was a chemical burn.

Jeez, that is scary. Hopefully they will heal soon.

It looks like a ceramic fuse but instead of being white, it's a darkish gray. I have a white ceramic 250v 10A fuse that I was thinking of using until I can get a 20A one. Worst case is it'll blow if I go over that limit, right?

It was probably white until it blew.

Yes a 10A will blow faster than a 20A fuse if you measure more than 10A.

For the longest time, my multimeter screen would go out. Like I could read all the numbers some of the time but other times it was cutting out. I ripped apart the screen part and cleaned everything. There were glass connectors.

Some older Fluke multimeters also had a similar problem with fading digits.

[Spork Schivago]

Re: HP 2007W LCD Monitor

I always wanted a Fluke. They're real nice. I keep looking in Craigslist for a used one but so far nothing. Could you recommend a good model number for one?

[retiredcaps]

Re: HP 2007W LCD Monitor

I always wanted a Fluke.

If you are patient, you will eventually get a good deal on an used Fluke. I have 3 of them and purchased them all used.

Could you recommend a good model number for one?

What is your budget? Do you mind buying used?