Gateway 24" LCD Model LP2407

[momaka]

Re: Gateway 24" LCD Model LP2407

Here is the order for the Logic Board capacitors, the only one I was a bit iffy on was the last one but I think I got it right as well...

List looks good to me. For the last one, you could have gone with a 25V or even a 50V cap so that you can find Panasonic FC/FR/FM or other equivalent low ESR caps. But what you got will still probably work. The LCD logic board typically rarely requires low ESR caps.

_ I will order some IPA, or can I just pick it up at CVS/Wallgreens, etc?

Yes, you can get IPA from CVS or any other pharmacy store. Just try to get one that has 90% or higher alcohol content. I've used regular rubbing alcohol before as well (I think that is somewhere in the 70% mark) and it worked. But the 90% and higher dries faster and dissolves flux better.

_ Which brings me to... Can I steal some of the wife's "Regular Polish Remover" from CVS to clean off the brown glue residue from that other project you are helping me with (Klipsch speaker)?

Yes.
I'm not sure how well it will work, but I think it should. Nail polish remover usually has Acetone in it, as well as a few other organic solvents similar to Acetone. So give it a try.

_ I am not sure what kind of flux I got. It does say a bunch of stuff in Mandarin (I think), and the brand is Longyuan.

It's very likely regular rosin flux. Just in solid form. Good enough for regular everyday soldering.

Ok, I completely removed the LCD Inverter and the little USB board, I plugged in the logic board to the power board (flipped and on the back of my mouse pad) then I plugged in the power board and took all the same measurements as before:

LCD INVERTER CN ON THE POWER BOARD (left to right towards LCD Inverter):
1. 0V
2. 3.28V
3. 0V
4. 5.18V
5. 0V
6. 0V
7. 25.9V
8. 25.9V

LOGIC BOARD CN ON THE POWER BOARD (starting from the red cable)
1. 5.18V
2. 5.18V
3. 5.18V
4. 5.18V (also red)
5. 0V
6. 0V
7. 0V
8. 0V
9. 3.28V
10. 0V

See that 3.28V? That's either the backlight dim/brightness signal or the inverter ON/OFF signal from the LCD logic board. Thus, it looks like LCD logic board may be fine as well (by that, I mean not dead from when you thought you had shorted the power supply or when the sparks came off from that connector on the inverter board).

As a next step, I would say try to fix your solder joints on the inverter board and measure all of the voltages again. If all is good, these voltages should remain more or less the same to what they are now.

The logic board caps are here

Should I start swapping those mofos? Though I could wait for the better iron to see how that one handles the job...

Wait for the (hopefully) better iron. The 30 Watt iron will make you want to cry if you attempt to change caps on the LCD logic board.

Also, do the test I suggested above first. That way, we know if the inverter is shorting the power supply or not.

[USchabon]

Re: Gateway 24" LCD Model LP2407

The logic board caps are here

Should I start swapping those mofos? Though I could wait for the better iron to see how that one handles the job... What do those readings with the logic board plugged in tell you?

[USchabon]

Re: Gateway 24" LCD Model LP2407

Here is the order for the Logic Board capacitors, the only one I was a bit iffy on was the last one but I think I got it right as well...

[USchabon]

Re: Gateway 24" LCD Model LP2407

GENERAL SOLDERING STUFF:
_ I will order some IPA, or can I just pick it up at CVS/Wallgreens, etc?

_ Which brings me to... Can I steal some of the wife's "Regular Polish Remover" from CVS to clean off the brown glue residue from that other project you are helping me with (Klipsch speaker)?

_ I am not sure what kind of flux I got. It does say a bunch of stuff in Mandarin (I think), and the brand is Longyuan. Either way, I am good to go there and will use some IPA to clean it all off from my soldering catastrophes.

_ I have been using a little damp sponge to clean the tip, but I think I need more practice. Re-heating all of the cloudy looking ones should help me get better.


ON TO THE ACTUAL PROJECT:

Yes sir!
You got a healthy-looking power supply producing 5V and 24V.

Arms up, rocky theme song... Waaaaait, no, no, no... that's what I will do if this thing gets fixed

Well, at least now you know better.
Sometimes, making mistakes is the best way to learn

Yup!

These are the other common board designators:
C: capacitor
R: resistor
L: inductor or choke
J: metal jumper (piece of wire)
D: diode
Q: transistor of some sort (BJT, MOSFET, IGBT, etc.)
T: transformer
FB: ferrite bead (a very small inductor, typically)

Glad I'll be able to reference back to all these threads whenever I need to in the future.

But as far as the caps for the logic board - yes, you can go ahead and order those as soon as we verify that the logic board is not shorted. To do that (test the logic board), simply plug in the logic board to the power supply but do NOT plug in the inverter board. Then, measure those voltages on the two connectors of the power board again and post results here. Hopefully, we should still see those 5V and 24V rails again.

Ok, I completely removed the LCD Inverter and the little USB board, I plugged in the logic board to the power board (flipped and on the back of my mouse pad) then I plugged in the power board and took all the same measurements as before:

LCD INVERTER CN ON THE POWER BOARD (left to right towards LCD Inverter):
1. 0V
2. 3.28V
3. 0V
4. 5.18V
5. 0V
6. 0V
7. 25.9V
8. 25.9V

LOGIC BOARD CN ON THE POWER BOARD (starting from the red cable)
1. 5.18V
2. 5.18V
3. 5.18V
4. 5.18V (also red)
5. 0V
6. 0V
7. 0V
8. 0V
9. 3.28V
10. 0V

[momaka]

Re: Gateway 24" LCD Model LP2407

I got this iron with the 5-tip combo on its way: http://www.ebay.com/itm/371655422595

Interesting iron. It uses the same 900M style tips I was talking about, but plugs in directly to the wall (i.e. no base / head unit).

I hope the 900M tips you got with that iron fit tightly on the iron's heater. Otherwise, it could be like those low-quality temperature-controlled stations I was talking about in my previous post. But I guess it is okay for the price. At least you didn't spend $30-40 on a cheap temperature-controlled station that uses those tips. Some of them have waaay too low quality tips and thus have terrible temperature control. In fact, this is primarily why I posted this before:
https://www.badcaps.net/forum/showthread.php?p=559411

About the flux, thank you for pointing that out (and thank you for everything you are pointing out!! you rock man, seriously thankful for everything you are teaching me!!). I will start doing it that way from now on, and I guess I will not use the part that got melted multiple times and instead use little bit from the other side of the little box of flux I got in my first iron's kit.

No problem
You can use the melted side if you scrape enough of the melted stuff off. Alternatively, you can crush that melted stuff and dissolve in a few drops of IPA.

... to what I've been calling the LCD board (the one with the Frankenstein soldering job )

If you are referring to this board:
https://www.badcaps.net/forum/attach...1&d=1466290679
https://www.badcaps.net/forum/attach...4&d=1466217947
... that would be the LCD inverter board. What that board does is it takes low-voltage from the power supply (typically 12-24 Volts) and boosts that to 700-1000 V (but high-frequency AC) needed to light up the CCFLs (cold cathode fluorescent lights).

Here are the readings for the cable going

From left to right (moving up towards the LCD board):
1. 0V
2. 0V
3. 0V
4. 5.43V
5. 0V
6. 0V
7. 23.3V
8. 23.3V

Here are the readings for the cable going to what I've been calling the logic board (the one with all the processors and the I/O inputs)
1. 5.43V
2. 5.43V
3. 5.43V
4. 5.43V
5. 0V
6. 0V
7. 0V
8. 0V
9. 0V
10. 0V

I think I am seeing a pattern here

Yes sir!
You got a healthy-looking power supply producing 5V and 24V.

I think you are underestimating the level of stupidity I was exercising while sleepy and starving (cause I was too excited to do this that I didn't cook anything when I got home, lol...

Don't worry. We all have our bad days.
The most important thing is nothing bad happened to you (could have stuck your hand/fingers somewhere on the power supply where you weren't supposed to and gotten shocked)

I literally had the board resting crooked and sideways at an angle so that the the part of the chassis that has the holes for the I/O inputs could make a better connection between just about any pair of soldering points on the underside of that board, yay for idiots with soldering guns! hahah...

Well, at least now you know better.
Sometimes, making mistakes is the best way to learn

But I will not let this discourage me! I am having way to much fun

Good!

I see a bunch of 852's but no "CN852". Can you please help me figure out which one you are referring to?

Text on the power board on the bottom left of this picture:
https://www.badcaps.net/forum/attach...5&d=1466291910

The board designator/prefix "CN" means Connector. 852 is just a number to distinguish it from another connector. Why the numbering starts from 850-something... I don't know .

These are the other common board designators:
C: capacitor
R: resistor
L: inductor or choke
J: metal jumper (piece of wire)
D: diode
Q: transistor of some sort (BJT, MOSFET, IGBT, etc.)
T: transformer
FB: ferrite bead (a very small inductor, typically)

Maybe we should go ahead and order that cable now so that it gets here when we are done with the rest? And order the caps for the logic board as well?

We can leave the connector for now. In fact, you don't even need to plug in the inverter board at all to see if the monitor is working. You just won't be able to see anything on the screen (well, you might be able to if you point a flash light close to its surface - this is usually done to check for image/signal when the inverter board isn't working).

But as far as the caps for the logic board - yes, you can go ahead and order those as soon as we verify that the logic board is not shorted. To do that (test the logic board), simply plug in the logic board to the power supply but do NOT plug in the inverter board. Then, measure those voltages on the two connectors of the power board again and post results here. Hopefully, we should still see those 5V and 24V rails again.

Finally, I have 3 questions about soldering and PCBs. Taking a look at this photo...
1. These two look too close for comfort. They were like that before. Does it look like I need to re-do any connections that look like that so that they don't touch? If yes, do you have any tips?
2. Would these wet looking remnants of Flux be a concern?
3. Should I worry about my hack job leads touching the PCB?

https://www.badcaps.net/forum/attach...1&d=1466400403

1. No, those are okay, because they are connected to the same trace. On your board, the light green traces (or "tracks" if you like) are actually copper traces underneath that connect the various solder joints. Thus, two solder joints that are connected to the same light green trace are also connected to each other. In contrast, the dark green spots on your board are non-conductive areas - they separate the light green traces from each other.

2. Usually no, if it's rosin-type flux. But I usually remove it anyways (with IPA), just so that the board looks neater and because I use RMA-type flux (which can corrode bare copper traces a little bit over time).

3. NO, if they don't contact other traces that they are not connected to.
That said, you could trim your leads a little bit more. It will make the solder job look better. Also, your joints look somewhat cloudy, as if your iron's tip was dusty/dirty and that dirt got transferred onto the joint. Either way, it's usually a good idea to clean your iron's tip every once in a while. You can do that either with a damp sponge or damp piece of paper towel. When the iron heats up to temperature, wipe the tip over the damp sponge / paper towel, then coat with fresh solder.

After you do all of that, put a little bit of flux again on those cloudy joints and re-heat them with your iron again. Hold the iron for 1-3 seconds on the joints. When you remove the iron, the joint should look a lot cleaner.

[USchabon]

Re: Gateway 24" LCD Model LP2407

It would make sense to think there was something wrong with the logic board because of the logo not fading away quickly, and other weird little things I saw it do before. But totally agree that we need to confirm the power unit is good before doing anything else.

I got this iron with the 5-tip combo on its way: http://www.ebay.com/itm/371655422595

About the flux, thank you for pointing that out (and thank you for everything you are pointing out!! you rock man, seriously thankful for everything you are teaching me!!). I will start doing it that way from now on, and I guess I will not use the part that got melted multiple times and instead use little bit from the other side of the little box of flux I got in my first iron's kit.

Here are the readings for the cable going to what I've been calling the LCD board (the one with the Frankenstein soldering job )

From left to right (moving up towards the LCD board):
1. 0V
2. 0V
3. 0V
4. 5.43V
5. 0V
6. 0V
7. 23.3V
8. 23.3V

Here are the readings for the cable going to what I've been calling the logic board (the one with all the processors and the I/O inputs)
1. 5.43V
2. 5.43V
3. 5.43V
4. 5.43V
5. 0V
6. 0V
7. 0V
8. 0V
9. 0V
10. 0V

I think I am seeing a pattern here

Well, I looked at your pictures carefully, and it appears that the power board is raised on metal stand-offs from the metal surface of the chassis. So unless you didn't trim the cap leads to proper lengths, that power board should bot be able to touch the metal chassis of the monitor. If you fear that it does, you could use either electricians tape or clear plastic from food container packaging... or cardboard (but I wouldn't leave these last two as permanent fixes).

I think you are underestimating the level of stupidity I was exercising while sleepy and starving (cause I was too excited to do this that I didn't cook anything when I got home, lol...

I literally had the board resting crooked and sideways at an angle so that the the part of the chassis that has the holes for the I/O inputs could make a better connection between just about any pair of soldering points on the underside of that board, yay for idiots with soldering guns! hahah...

But I will not let this discourage me! I am having way to much fun

I can prevent that from happening again by (as you said) resting it properly on its intended mounting points. There already is some kind of isolation mat under the power unit, so that's that really. Safe.

I can also prevent contact with the chassis and the LCD board by laying down a double layer of electrician's tape where the Frankenstein soldering points are (this is already done and dusted). There is no doubt at all whether there was contact or not, it is 100% certain that it did happen. there is about 1.5mm of clearance and I needed about 2.5mm or more.

I see a bunch of 852's but no "CN852". Can you please help me figure out which one you are referring to?

Maybe we should go ahead and order that cable now so that it gets here when we are done with the rest? And order the caps for the logic board as well? Or are you afraid we might not get that far before declaring it dead for good?

Finally, I have 3 questions about soldering and PCBs. Taking a look at this photo...
1. These two look too close for comfort. They were like that before. Does it look like I need to re-do any connections that look like that so that they don't touch? If yes, do you have any tips?
2. Would these wet looking remnants of Flux be a concern?
3. Should I worry about my hack job leads touching the PCB?

[momaka]

Re: Gateway 24" LCD Model LP2407

Zero, nada, zilch. Screen stays black and doesn't even budge no matter what. Tried DVI from computer and component from cable box.

And LED doesn't change color or indicate that signal has been detected?

If yes, then the next step would be to check the voltages of the regulators on the LCD video/logic board and most likely change the its caps too. (I will walk you through the steps to check those voltage regulators, but that would be after we check the power supply, since that could be an issue now as well.)

Lots of hot spots on this monitor. The LCD board was a different color towards the bottom, and the logic board as well around the chips. See below.

Man, this thing looks like it came out of an oven.

I'm pretty sure that the caps you see in this picture...
https://www.badcaps.net/forum/attach...2&d=1466290679
... have dried up from all of the heat. They are Teapo brand too, which is well known for going bad on hot equipment. But again, we will get to this matter after checking the PSU (power supply unit).

Maybe I should get a 60W. Are adjustable irons a lot more? I guess with a 30W and a 60W I would be solid for anything, but might be nice to be able to dial it in in between..?

Depends what kind of "adjustable" iron you get. There are two types: adjustable power and adjustable temperature.

Adjustable power is more or less the same thing as your 30 Watt iron, except just with a knob to adjust... well, power . But that isn't as helpful as it may sound. What really matters is the tip temperature and how much heat the tip can "store" before becoming too cold to melt solder. Thus, you don't really need an adjustable power iron. A regular iron with a good tip will do just as well, as long as you select the right power rating for your needs. Moreover, you can typically get two regular irons for the price of one adjustable power iron. And with two irons, you can remove SMD/SMT components much easier than with a single iron.

As for adjustable temperature irons (also known as a temperature-controlled irons or "soldering stations"): if properly built, these irons are the best to have, because then it doesn't matter how big the solder joint or the iron's tip is - the iron will pump more power into the tip, as needed, to keep the tip's temperature steady so that it never goes too cold to melt solder. *HOWEVER*, this category of irons varies quite a bit in quality. The low quality soldering stations can underperform quite badly - sometimes being less effective even than your inexpensive 30 Watt iron.
Usually, these low quality irons are the ones that use Hakko 900M style "clone" tips.

IMO, if you don't do a lot of soldering, then having one or two decent "regular" fixed power irons should suffice. But if you are serious and plan to solder a lot, I would recommend you spend a little more and get a soldering station that uses the T12/T15 or other similar cartridge-type tips with built-in heating element. Something like Aoyue 2900 or CSI 2900 is about as cheap as you get those (the CSI 2900 still goes for $60). I have the latter and there's nothing I can't solder with that.

Anyways, sorry to derail you thread with all of that info. But hopefully it gives you a good idea of what your iron(s) can be used for and/or how well they'd perform when stacked against other options.

I also used the flux on all soldering points. I would melt the flux with the iron, then dip the lea into it as it cooled coating the tip with a little drop of flux. I thought it was to clean the soldering point to allow the metals to fuse, but I did notice that both the flux and the actual molten metal helped a lot with heat transfer.

Well the thing about flux is that it is only "good" for a second or so after being heated (that's when it becomes activated and cleans/burns away impurities in the solder). So melting it with your iron and then applying it on the solder joint isn't very effective. It will also destroy your tip faster if you apply it directly on the tip too much.
Maybe try breaking some piece of flux and putting them on the joints, then heat with the iron. That should work much better.

Right, Ebay. Found this one for $12. I like that it is adjustable (though the numbers in the dial are probably the least accurate thing ever), and I really like that the distance from the handle to the tip is much shorter than the one I have now. Nice plus that it comes with more wire and 5 changeable tips. Order placed!

Don't see a link here. Could you show us which one?

Well at some point I think I may have fried the power........... when I plug it in now I hear a very low buzzing sound for about a second and absolutely nothing happens...........

[b]I THINK WE NEED TO LOOK AT THE POWER UNIT, test it somehow

Alrighty, time to pull out your multimeter again

Test #1: check for power supply stand-by voltage(s).

1) Disconnect cables between power supply board and LCD logic/video board as well as inverter board (that would be the broken one, so make sure to temporarily isolate the pins with tape for this test)

2) With the power supply safely resting on its stands in the LCD monitor chassis (preferable) or on a *non-conductive* (i.e. non-metal) surface, plug in the power supply to the wall.
**NOTE** some metal parts of the power supply are at *LINE* potential and thus pose a risk of electrocution. Avoid touching any components on the power supply - particularly the aluminum heatsink around the big high-voltage capacitor and surrounding components. Only the monitor chassis is generally safe to touch.

3) Set your multimeter to *DC* voltage measurement (20V scale should suffice here), and place the black (-) probe on either the monitor chassis or on one of the metal screws that hold down the power supply.

4) With the red (+) multimeter probe, test the voltage you get on each pin of the two cables that go to the LCD logic/video board and inverter board (CN852?).

It appears that this monitor has only two voltage rails - likely 5V and 12-24V (on that note, if you get a single "1" digit on the left side of the multimeter screen, that means the voltage on the pin has exceeded the range of the test scale, so set multimeter to next higher scale). So that's what we should get here if everything is working. Nonetheless, post all of the voltage you get and on which connector. Like this:

CNxxx:
pin 1 - xx volts
pin 2 - xx volts
...
and so on.

So, I assembled the whole thing and rested all the components on the metal chassis... The problem is that the underside of the power board may have touched the chassis (99% sure it did)...

Well, I looked at your pictures carefully, and it appears that the power board is raised on metal stand-offs from the metal surface of the chassis. So unless you didn't trim the cap leads to proper lengths, that power board should bot be able to touch the metal chassis of the monitor. If you fear that it does, you could use either electricians tape or clear plastic from food container packaging... or cardboard (but I wouldn't leave these last two as permanent fixes).

I didn't think about this and the these being the worst soldering jobs they definitely 100% touched the chassis.

Have a look and see if it does so we can remove any doubts about that.

Ok, sounds good. How do I test that?

I'm going to use the picture of the PSU board (bottom side) in post #29 as a reference:
https://www.badcaps.net/forum/attach...9&d=1272309869

You see those thin traces running between connector CN852 and the other connector that plugs in to the LCD logic/video board? - Those are backlight turn-ON signal and backlight dimming signals going from the logic board to the invert board. They only pass-through the power supply board but aren't really affected by it. See if the broken pins on that connector that sparked actually touched those pins that connect to the thin traces. If yes, that could potentially be trouble.

I do have some non corrosive glue on its way, picked out by Budm. Sounds like it will be perfect for the job. I am game for ordering the cable though, but I guess first we should find out if the whole thing is garbage now that the thing won't turn on.

https://www.amazon.com/GC-Electronic.../dp/B004SPJN6K

That will work indeed.
Yes, we can look for a cable after everything else is determined to be in okay/working condition. For now, just patching that cable up for a test or two is all that is needed.

Also, I just had this idea: you can wrap tape around the metal parts of each female pin before plugging it into the broken plastic. That should keep things from shorting even better.

[USchabon]

Re: Gateway 24" LCD Model LP2407

All caps look OK, the only one that could be slightly bulged is marked with a red arrow, but it may be pseudo confirmation bias... take a look. I do have extras for all of them since I ordered enough for 2 monitors.

Also adding a detailed photo of the cable with the leads that are loose now... Only one of them has no plastic housing, the other three can be placed back in the remains of the plastic.

I suppose I could rig the whole thing with a lot of glue applied after I make the connections to make sure they don't touch each other, but it will be tricky.

[USchabon]

Re: Gateway 24" LCD Model LP2407

Could you tell more specifically what you mean by "no image"? Black screen, gray screen, white screen? Does the screen turn OFF after a few seconds? What about if you connect it to a signal source - same thing?

Zero, nada, zilch. Screen stays black and doesn't even budge no matter what. Tried DVI from computer and component from cable box.

No, you can't really fry the board like that. The only damage you can do is lift or rip traces off. That usually happens more often if the iron is too weak (i.e. not hot enough) than too hot. So it looks like your 30 Watt iron is just not strong enough for the inverter board or any other multi-layer.

I guess I should have guided you a little better and recommended only the 60 Watt iron.

I don't think it is the iron, though it maaaaay have helped a bit since you say I can't fry the board then it would have made it easier to remove that pin and also sped things up. Maybe I should get a 60W. Are adjustable irons a lot more? I guess with a 30W and a 60W I would be solid for anything, but might be nice to be able to dial it in in between..?

That said, have you tried using the provided rosin flux with your iron kit? If not, definitely give it a try. From the pictures of that kit, it looks like the flux comes as a solid. That means you need to chip small pieces each time you need to use any and dissolve the pieces in a few drops of IPA (Isopropyl Alcohol). Then, with the dissolved flux, you apply it on all of the joints you are struggling with and heat them up with you iron again. The flux should improve the heat transfer from the iron to the joint greatly. But make sure you iron has been plugged in for at least 5 minutes prior to that.

I had my iron plugged in the whole time to keep it as hot as it would go. The handle was too hot to hold at the very end. I also used the flux on all soldering points. I would melt the flux with the iron, then dip the lea into it as it cooled coating the tip with a little drop of flux. I thought it was to clean the soldering point to allow the metals to fuse, but I did notice that both the flux and the actual molten metal helped a lot with heat transfer.

If you continue to struggle with that 30 Watt iron, there are auctions on eBay just for a 60 Watt iron and no accessories. I think those could be found as cheap as $3-5 (or you can try the irons from Home Depot I suggested previously). Having the right soldering iron for the job is really important. I've seen people who have never soldered before solder like a Pro when given the proper equipment. Same people struggled quite a bit before that with a cheap iron. Actually, I sort of started like that too.

Right, Ebay. Found this one for $12. I like that it is adjustable (though the numbers in the dial are probably the least accurate thing ever), and I really like that the distance from the handle to the tip is much shorter than the one I have now. Nice plus that it comes with more wire and 5 changeable tips. Order placed!

If it was the power board, you wouldn't get power.
Just to rule out the inverter board... when you plug in a signal into the monitor, do the screen backlights come ON ans stay ON? What about the power LED on the monitor? Does it turn ON / change color to indicate that the monitor is receiving a signal?

Well at some point I think I may have fried the power........... when I plug it in now I hear a very low buzzing sound for about a second and absolutely nothing happens...........

I THINK WE NEED TO LOOK AT THE POWER UNIT, test it somehow, cause I probably fried the whole f-in thing when I tried plugging in that cracked cable and it sparked really bad.

I also have not seen pictures of the LCD logic/video board yet. Could you post a few? Some monitors have badcaps on those as well. The worst thing about it is that the caps there are usually small and almost never show signs of being bad. But if the logic/video board has hot parts or has been running hot, those caps can get toasted and eventually cause all sorts of issues too.

We usually don't ask people to change them simply because most of the time those caps are not always critical and the logic/video board has really thick copper traces - makes it really hard for novices to change the caps on it. I would NOT attempt it at all with anything less than a 50 Watt iron.

Lots of hot spots on this monitor. The LCD board was a different color towards the bottom, and the logic board as well around the chips. See below.

Oi! Is your new cap not bulged yet?
Typically when you install caps in backwards, it takes only a few seconds for them to go bad when you apply power.

Nope. No bulging noticeable at all.

, when you were testing the monitor, did you have the monitor assembled back properly? ... or at least part way so that the boards are not resting on the metal chassis of the monitor?

I know it may seem like a stupid question (and sorry if it is, as I don't quite know your skill/knowledge level), but I ask because I've seen people try to test motherboards on bare metal surfaces... and the results weren't so pretty. :\

If that's not what happened here, then the crackle could be from a component burning out (hence, why you only head it once).
*BUT*
Does the monitor still exhibit the same symptoms now?

Yup. This is the problem now...

So, I assembled the whole thing and rested all the components on the metal chassis... The problem is that the underside of the power board may have touched the chassis (99% sure it did)... I was just too freaggin' tired and hadn't eaten...

Also, the LCD board had tiny little soldering points on the back of the PCB, which wouldn't have touched the bare chassis when fully mounted. I didn't think about this and the these being the worst soldering jobs they definitely 100% touched the chassis.

Wow, that is some pretty horrible plastic burn. The monitor must have been running extremely hot inside. More reason now to post picture of the LCD logic/video board, as the caps on it could well be done.

Ok, 3rd photo added.

The power board usually has good protection against short-circuit, so you probably did not fry it. I don't see any fuses either, so everything should be okay.

As for the inverter board where that broken cable plugs into... depends which pins got shorted. Inverter boards typically have 4 inputs: power, ground, backlight ON (BL_ON or ON), and backlight brightness (DIM). Sometimes the power may be separated into two rails: one for the inverter controller (usually 5-12V) and another for the backlights only (12-24V).

Either way, just see which pins got shorted. If it is power to ground, then probably nothing got fried. But if it's power to one of the logic inputs (i.e. BL_ON or DIM), that could be a problem.

Ok, sounds good. How do I test that?

You can probably just get the plastic for that broken connector on Digikey or Mouser instead of looking for a whole cable - should be easier. But you would need to measure its size (length, width, height) and pin pitch (i.e. spacing between the pins) before looking for a replacement.

IMO, if you can fix that connector, that may be the easiest thing to do. Probably just glue it back together, if possible. The glue will need to be non-corrosive, though.
If you have hot glue (a.k.a. hot-melt glue), you can give that a try. It's not the best glue in the world (especially in a monitor that runs hot), but it is safe for electronics. Should at least allow you to test the monitor for now.

I thought the same. It will be very tricky but as long as it is safe long term that's all that matters. I do have some non corrosive glue on its way, picked out by Budm. Sounds like it will be perfect for the job. I am game for ordering the cable though, but I guess first we should find out if the whole thing is garbage now that the thing won't turn on.

https://www.amazon.com/GC-Electronic.../dp/B004SPJN6K

[momaka]

Re: Gateway 24" LCD Model LP2407

Well I am pretty sure I am the worst solderer EVER...

.... Mhhh... No. You will have to work a lot harder if you want that title . Believe it or not, I have seen worse.

I swapped all the caps I mentioned and I am still getting the same, the buttons light up but I have no image.

Could you tell more specifically what you mean by "no image"? Black screen, gray screen, white screen? Does the screen turn OFF after a few seconds? What about if you connect it to a signal source - same thing?

Is there a way to test whether I even got a connection on my two first (and WORST) solders?

Set multimeter to continuity (beep mode)... typically, this is also diode test.
Put one probe on a trace on the board where the capacitor lead connects and another on the capacitor lead's solder joint. If you get a beep, you got a connection.

I couldn't get the pin to slide out and I made the horrible mistake of cutting it thinking it would be easier to pull out the little bit left in the hole.

If you have cutter pliers, you can still pull it out. Looks like you have the clearance on the side of that. So simply grab the pin with the cutters and use the board as a leverage to pull the pin out. Of course, while doing that, also heat the pin with your soldering iron on the other side of the board.

After a seemingly successful replacement of all power unit caps (way easier for some reason)

The power board has only a single layer of traces, so this typically makes them easier to work on.

I went back to try to pull the pin and it just wouldn't come out. I might have fried the board trying to heat it up but no matter what I tried I just couldn't

No, you can't really fry the board like that. The only damage you can do is lift or rip traces off. That usually happens more often if the iron is too weak (i.e. not hot enough) than too hot. So it looks like your 30 Watt iron is just not strong enough for the inverter board or any other multi-layer.

I guess I should have guided you a little better and recommended only the 60 Watt iron.

That said, have you tried using the provided rosin flux with your iron kit? If not, definitely give it a try. From the pictures of that kit, it looks like the flux comes as a solid. That means you need to chip small pieces each time you need to use any and dissolve the pieces in a few drops of IPA (Isopropyl Alcohol). Then, with the dissolved flux, you apply it on all of the joints you are struggling with and heat them up with you iron again. The flux should improve the heat transfer from the iron to the joint greatly. But make sure you iron has been plugged in for at least 5 minutes prior to that.

If you continue to struggle with that 30 Watt iron, there are auctions on eBay just for a 60 Watt iron and no accessories. I think those could be found as cheap as $3-5 (or you can try the irons from Home Depot I suggested previously). Having the right soldering iron for the job is really important. I've seen people who have never soldered before solder like a Pro when given the proper equipment. Same people struggled quite a bit before that with a cheap iron. Actually, I sort of started like that too.

How can I test with a multimeter if it is the power unit or the LCD board that is giving me issues?

If it was the power board, you wouldn't get power.
Just to rule out the inverter board... when you plug in a signal into the monitor, do the screen backlights come ON ans stay ON? What about the power LED on the monitor? Does it turn ON / change color to indicate that the monitor is receiving a signal?

I also have not seen pictures of the LCD logic/video board yet. Could you post a few? Some monitors have badcaps on those as well. The worst thing about it is that the caps there are usually small and almost never show signs of being bad. But if the logic/video board has hot parts or has been running hot, those caps can get toasted and eventually cause all sorts of issues too.

We usually don't ask people to change them simply because most of the time those caps are not always critical and the logic/video board has really thick copper traces - makes it really hard for novices to change the caps on it. I would NOT attempt it at all with anything less than a 50 Watt iron.

Thank you very much Mickey! Ok, so I reversed that cap. No, it still looks like crap I wasn't able to make it better

Oi! Is your new cap not bulged yet?
Typically when you install caps in backwards, it takes only a few seconds for them to go bad when you apply power.

On to the bad news... when I plugged it in I heard a quiet crackle noise. I am 90% sure it was the solder on the bottom of that LCD board touching the metal beneath. I applied electrical tape on the metal chassis and tried again, no crackle...

Wait, when you were testing the monitor, did you have the monitor assembled back properly? ... or at least part way so that the boards are not resting on the metal chassis of the monitor?

I know it may seem like a stupid question (and sorry if it is, as I don't quite know your skill/knowledge level), but I ask because I've seen people try to test motherboards on bare metal surfaces... and the results weren't so pretty. :\

If that's not what happened here, then the crackle could be from a component burning out (hence, why you only head it once).
*BUT*
Does the monitor still exhibit the same symptoms now?

#$&$%!!! It looks like the plastic was very brittle from being exposed to heat for many years and it cracked pretty badly when I tried to plug it back in.

Wow, that is some pretty horrible plastic burn. The monitor must have been running extremely hot inside. More reason now to post picture of the LCD logic/video board, as the caps on it could well be done.

I tried plugging it in anyway, carefully, and I almost crapped myself when a big ass spark came flying out of the broken cable socket.

1. How can I test if I fried the power control unit?

The power board usually has good protection against short-circuit, so you probably did not fry it. I don't see any fuses either, so everything should be okay.

As for the inverter board where that broken cable plugs into... depends which pins got shorted. Inverter boards typically have 4 inputs: power, ground, backlight ON (BL_ON or ON), and backlight brightness (DIM). Sometimes the power may be separated into two rails: one for the inverter controller (usually 5-12V) and another for the backlights only (12-24V).

Either way, just see which pins got shorted. If it is power to ground, then probably nothing got fried. But if it's power to one of the logic inputs (i.e. BL_ON or DIM), that could be a problem.

2. Where can I order a replacement for that cable?

You can probably just get the plastic for that broken connector on Digikey or Mouser instead of looking for a whole cable - should be easier. But you would need to measure its size (length, width, height) and pin pitch (i.e. spacing between the pins) before looking for a replacement.

IMO, if you can fix that connector, that may be the easiest thing to do. Probably just glue it back together, if possible. The glue will need to be non-corrosive, though.
If you have hot glue (a.k.a. hot-melt glue), you can give that a try. It's not the best glue in the world (especially in a monitor that runs hot), but it is safe for electronics. Should at least allow you to test the monitor for now.

[USchabon]

Re: Gateway 24" LCD Model LP2407

I am impatient... did I mention that?

I tried plugging it in anyway, carefully, and I almost crapped myself when a big ass spark came flying out of the broken cable socket.

1. How can I test if I fried the power control unit?
2. Where can I order a replacement for that cable?

[USchabon]

Re: Gateway 24" LCD Model LP2407

Thank you very much Mickey! Ok, so I reversed that cap. No, it still looks like crap I wasn't able to make it better

Good news is I tested it like you said and I get a beep when I put the negative to the pin and the positive to the third pin from the bottom on the power connection at the bottom left (next to the yellow sticker with a barcode). So it looks like there is a good connection.

On to the bad news... when I plugged it in I heard a quiet crackle noise. I am 90% sure it was the solder on the bottom of that LCD board touching the metal beneath. I applied electrical tape on the metal chassis and tried again, no crackle... BUT... and here is the really annoying BUT...



#$&$%!!! It looks like the plastic was very brittle from being exposed to heat for many years and it cracked pretty badly when I tried to plug it back in.

Now I am going to have to order this cable and I will have to wait to find out if I fixed it, or if I fried it Can someone please help me order that cable?

[mikey5791]

Re: Gateway 24" LCD Model LP2407

Hi USchabon,

Refer back your picture on post #59, on the original bulging
Nichicon 470uF 35V cap near C1,C2 - please desolder your new cap
and follow the original cap position in your new soldering job. While desoldering, when the solder is melting maybe you can try a small plier to pull off the extra leftover pin.

Since you are eager to know whether there is a good connection on those two suspect soldering jobs, the easy way is to test for continuity from your multimeter(DMM). Set your DMM to diode/continuity test, put one cap pin to your black probe and red probe to your pcb track. Then swap the probe. If the
connections are good, you should get both same readings.

[USchabon]

Re: Gateway 24" LCD Model LP2407

Thank you for your reply Mikey!

OMG.. you are right... man, the job on those two caps is cursed!

[mikey5791]

Re: Gateway 24" LCD Model LP2407

Hi USchabon,

Recheck connection on your Nichicon 470uF 35V cap near C1,C2.
Do you remember the original cap position, where the white stripe
part goes to on the pcb? refer second picture on post #67.

Noticed at C1 there is a '+' sign, normally a '+' sign is positive, which
refer to the cap lead side with no white stripe. The white stripe is usually
for the negative cap lead side.

[USchabon]

Re: Gateway 24" LCD Model LP2407

I would guess it has to do with the screen itself... I get no image with a DVI or with a component.

The lights of the menu turning on and off lead me to believe everything MIGHT be working fine but the LCD remains black.

I would love to test wether there is a good connection on those two suspect soldering jobs

[USchabon]

Re: Gateway 24" LCD Model LP2407

Well I am pretty sure I am the worst solderer EVER... I swapped all the caps I mentioned and I am still getting the same, the buttons light up but I have no image.

Is there a way to test whether I even got a connection on my two first (and WORST) solders? I couldn't get the pin to slide out and I made the horrible mistake of cutting it thinking it would be easier to pull out the little bit left in the hole.

After a seemingly successful replacement of all power unit caps (way easier for some reason) I went back to try to pull the pin and it just wouldn't come out. I might have fried the board trying to heat it up but no matter what I tried I just couldn't, so I rigged the whole thing trying to get the pin from the new cap to make contact with a lot of solder... frankenstein still wouldn't wake up.

It is clearly too much to ask, but try not to laugh at the second pitcure

How can I test with a multimeter if it is the power unit or the LCD board that is giving me issues?

[momaka]

Re: Gateway 24" LCD Model LP2407

Cool. Sucks that I got the wrong iron, but it is pretty warm here, usually around 27C or so in the room without the air on.

Okay, shouldn't be a problem then. I was worried if you are working in some place with sub 15C temperatures. At least that's when I find my 30 Watt iron to struggle a little. But it will all depend on what tip your iron comes with. If its tip is bigger, then that 30W rating won't be a problem at all.

Not sure if you mess with audio, but if you do please check this other thread out: https://www.badcaps.net/forum/showth...138#post664138

Oh, I do!
https://www.badcaps.net/forum/showpo...9&postcount=15
Will check your thread shortly.

[USchabon]

Re: Gateway 24" LCD Model LP2407

Cool. Sucks that I got the wrong iron, but it is pretty warm here, usually around 27C or so in the room without the air on. I could always get another if it gets tricky, and I bet letting it warm up will help. Thanks!

Not sure if you mess with audio, but if you do please check this other thread out: https://www.badcaps.net/forum/showth...138#post664138

[momaka]

Re: Gateway 24" LCD Model LP2407

You're welcome!

I hope that iron works well for you. Make sure to give it at least 5 minutes to heat up and apply fresh solder to the tip before trying to solder. I think you might have found it a bit easier to work with the 60 Watt iron. But this should work too, as long as you don't work in a very cold room.

...but it doesn't look like I ordered the big one, which seems to be a 450v 150uF. I guess I'll replace all of the other ones first, and see what happens.

Don't worry about that big cap. They rarely fail (even from the cheap brands). If yours was failed, you'd probably have noticed by now, as that usually blows the fuse and sometimes other parts too.