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Question Black Screen

May 24, 2020
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Black Screen... I have a HP dv4-2045dx laptop. Was working fine last night. Today I tried to upgrade the RAM and then I got a black screen. Swapped back to the old RAM, same thing. Tried one stick, both sticks, different positions, even tried the original RAM from a week ago before the first successful upgrade. I can hear the hard drive and fan. Can't get to bios, safe mode, nothing. LEDs for number lock and caps lock flash once every 3 seconds indefinitely. Can't seem to find that code anywhere. Tried everything I could think of and then some. Removed the CMOS battery for hours, reseated the RAM a bunch of times, tried discharging the capacitors by eliminating all power sources and holding the power button down for 15 seconds, 60 seconds, 90 seconds, tried an external monitor, took it apart down to nothing, couldn't see anything physically wrong, or anything disconnected. Tried booting it up with just the motherboard, RAM, and screen, nothing but fan, hard drive sounds, and black screen. Can't tell if I killed the motherboard by not wearing an antistatic strap or killed the RAM slot with a bad fit. I'm stumped. I couldn't leave well enough alone. I just got it running too like 2 weeks ago. Had a bent pin where the hard drive plugged in. At that time it would start up and it would tell me can't see the hard drive. Those were the good ol days. Any input would be greatly appreciated.. Thanks.
 
May 24, 2020
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I did try an external monitor and I got nothing. I can hear the fan and hard drive is on but the flashing LED's on the caps and number locks means there's a problem. I don't think it's on as in running windows and I just can't see it because the screen is dead. I think the blinking LED's means something is really wrong and even though I hear the hard drive and fan, it's still not booting up.
 

Jay_dog

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Apr 14, 2020
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First thing to do (as suggested by HP also) is: turn off your PC, unplug the charger, take out the battery, then open the RAM slot.

Take out the RAM and disconnect the wireless card.

Press the power button at that point, and keep it pressed for like 30 sec.

Reassemble it all and try to boot.

It may be a power problem or BIOS failure. Try this out; afterwards, it should be OK.

If that does not work, the worst scenario is that you just reset your BIOS from CMOS by taking out the small battery behind the RAM modules for a few seconds.

Hope the info helped.

Does it bot up at all on battery power?
 
Reactions: Dan_Highlander
May 24, 2020
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I did pull the wifi card already today, but I did not do the power button discharge with the wifi card out. I did the dicharge several times with it in. I have also pulled the CMOS several times, once for a few minutes, once for an hour. It doesn not boot up on battery or AC. It's on but doesn't ever boot up. I see the LED saying it has power, but no LED showing hard drive working. But I can hear it is on somewhat.
 
May 24, 2020
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I just pulled the wifi card, battery, AC cord, and the RAM, held the power button for 30 seconds, still nothing. Powers on, black screen, LEDs blinking every 3 seconds like clockwork.
 

lga1156_ftw

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Feb 25, 2020
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its the amd chip or northbridge 75%, check how to do reflow just to confirm. If you get picture with few minutes low temperature reflow (150celsius) then problem is inside the chip.

Before disassembly you can try leaving the laptop open for a night so it heats up, just leave it running on black screen then when you wake up press it on with power button and on again , if you this time get picture its 99% gpu / northbridge
 
Reactions: Dan_Highlander
May 24, 2020
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I have had my suspicions it's that too, but the timing would need to be the strangest of coincidences. It worked fine the night before. I shut it of and went to bed; the next day I got up, I never turned it on that day, I just immediately swapped the ram from a 1 gig and a 2-gig stick to two 2-gig stick. Then when I went to turn it on, it black screened and hasn't come back up since. A few days earlier I went from two 1-gig sticks to a 1-gig and a 2-gig sticks which successfully brought me to 3-gigs. When I turned it on, it black screened then too. I shut it off, pulled the battery, put it back in, and it came back up fine. I didn't think much of it because it came back up easily. I just assumed it was a fluke, until it did it again after the second RAM upgrade attempt a few days later. I just can't help but think it has something to do with the RAM slots themselves seeing how it black screened the last time I swapped RAM too. Maybe I somehow cracked an already weak solder joint between the slots and the board. I don't have a heat gun unfortunately. I am familiar with re-flowing, though I have never done a chip, I have watched a lot of videos. I do own a soldering iron, liquid flux, solder, thermal paste, pads, etc., even a microscope - not digital, and not big enough for a whole motherboard, (maybe if the chip is within 3 inches of the edge of the board or so) which I think it is if I remember from that last time I pulled it out. I have, using a hotplate, successfully removed and replaced single backlight LED's on LED strips in a 50-inch TV with the huge assist of the microscope, and have replaced an electrolytic capacitor in a stereo, so I can see myself re-flowing the chip if I had some hot air. I can't get much more than 180 degrees out of my hair dryer though, which won't even touch solder. I was thinking of leaving the laptop on, wrapping the laptop in a sweater or blanket, and carefully monitoring the temp at the fan output area with a cooking thermometer and try to let it get hotter than I could get it without a heat gun. If I can do that and see something on screen for even a moment after it cools, I'll know it's chip related. I’m not totally against the idea of a buying a new board I just don’t know if anyone has a dinosaur like this anymore. Haven’t had much luck searching for one, but I also don’t know all the places real knowledgeable people would look. So you think it's one or the other or possibly both chips under the heat sink? I assume those are the ones you're referring to? I really only pretend to have some knowledge in this, pardon my ignorance. AMD or Northbridge isn’t in my vocabulary yet. I know chip, capacitor, diode, mosfet, and basic electronic components.
 

lga1156_ftw

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There is only 1 large bga chip on the board looks like : https://www.aliexpress.com/item/2043250087.html

Im getting cold chills when i see that its the feared radeon 4250 , i can even remember chip model number 216-0752001 lol.
https://www.hklrf.com/216-0752001-SR880M-GPU-AMD-Mobility-Radeon-HD-4250_1210.html

I used to have a pile of laptops from different manufactors with this exact chip, only getting replacement worked 100%. But even that failed fairly soon its more like a design flaw. This is the point i started fearing all AMD gpu:s and still see red light when i hear anything amd related, i know its a bias and i should start trusting theyre stuff again but it was just horrible.

I dont mean complete reflow btw, first try the overnight or blanket if that dont get it to boot (you need to first close it and power on again) then try heat it to 150c with something, if you get picture the problem is INSIDE the chip, dont listen about cracked solderballs for that you would need to heat 225c to melt solder. This can happen also but less likely.

If you do get picture using these methods then do 2nd reflow near 200c when it fails again, you might get it to work for few months up to a year or not at all. Its a gamble and not complete fix.

Be picky if you replace motherboard, DO not get one with radeon 4250.
 
Reactions: Dan_Highlander

lga1156_ftw

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Before reflow try to remove the motherboard from the case, remove cmos battery and EVERYTHING from the motherboard, only leave heatsink on even fan connector remove. Plugin cable to external screen. keep ram connected obviously.

Now put it to non conductive surface and plugin power cable it should boot right away withoiut pressing power button since cmos battery is removed, if you get picture to external then problem is shorted component or cable from the removed components.
 
May 24, 2020
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I did pull and try the board yesterday, but it still had the RAM, CMOS, the power button, and I plugged in its own screen. I did not try it without the CMOS or an external monitor (at that point), but I have tried an external when it was reassembled and pulling the CMOS for quite some time. Perhaps I will try all that again but as you said. I do have an appointment to drop it off to real techs on the 29th, but if I figure it out before then... Do you know where this motherboard can be found? Or would I have to pull it out again and get the exact serial number or something off of it if I were to go that route before even trying? I do notice a few connection points on the board for ribbons and connectors not in use leading me to believe this board goes in more than one laptop with features I don't have.
 

lga1156_ftw

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Thing is when you buy "new" or "used motherboard" for this model it might have already replaced or "reflowed" gpu. Need to check closely for nvidia gpu model"EDITED out no cpu integrated graphics this model"

Found this old thread explaining the situation : https://www.badcaps.net/forum/printthread.php?t=34895&pp=40

I dont really suggest taking it to tech repair shop, well maybe for diagnosing the issue where they say its gpu / chipset issue, but like i said you can confirm it yourself already. They will probably just pull up a heatgun :D

Since you dont have dedicated gpu chip, you cant replace with different model. There is no integrated graphics in your cpu.

EDIT: and you can see these repair techs talking about replacing with new chip from china and even that fails after some time, just no point. Only thing you can try is reflow pretty much if its this chip what is failing.
 
May 24, 2020
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By the way, I took a reading of 2.89 volts from the CMOS battery when I had it out. You don't think there's any way this black screen can have anything to do with that battery being .11 volts low do you? I've read mixed comments on the subject. Some say yes it could stop it from booting up, some say no it only holds the clock. And I have never seen the clock off at all.
 
May 24, 2020
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See, I told you I was slow...lol I have it wrapped up in blankets now with a thermometer against the fan vent. Only showing about 125 F now. Hopefully the temp goes up higher. My next laptop, or if this one comes back to life, I'm going to Macgyver an external cooling fan that will run on a 12 volt power supply and keep it 20 degrees Fahrenheit cooler. I wonder if I should disconnect the fan and try this. I can almost take this thing apart down to nothing blindfolded now.
 
May 24, 2020
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Just like to say thanks to everyone that threw up some things to try. Just a quick update, (it's on) ~ I wrapped it up in blankets turned on so it couldn't breath and left a cooking thermometer against the fan output vent and measured 150 degrees Fahrenheit on the air coming out of that vent for 2 to 2.5 hours. I can only assume the AMD chip was close to 200 to 225 if the air coming out was 150, but I have no real way of knowing that. I put my hand on the keyboard and determined it was hot as a mofo, and I said okay, that's enough of that! It was real hot, like dangerously hot. Like hot enough to cook an egg in about 15 minutes if I left one on there or hot enough to kill something else. Gave it about 5 minutes to cool off and powered it on, the screen immediately came back to life. Said something about Bios and CMOS and resetting something or other, couldn't get my camera out fast enough before it went away. I got the idea though, I unplugged the CMOS battery a few times and it's resetting the BIOS I assume. Anyway, didn't seem like it was doing anything after that and I got nervous. I was probably just impatient and I shut it down. Turned it on again and Windows 10 began booting up immediately. Just to test fate, because I'm a dumbass like that, I shut it down, pulled the battery, pulled the AC cord, discharged the capacitors holding the power button for 15 - 20 seconds, and swapped the 1 GB RAM stick that was still in there for a 2 GB which is what got me in this mess to begin with, or so I thought. She came right up and has been running fine for the last hour showing 4 GB of RAM now. So... what do you think?... bad AMD? ... Need a new chip, and / or to be reballed or reflowed? I don't know, you tell me. I opened up System Information and this is what it read ~ AMD Turion(tm) II Dual-Core Mobile M500 2200 MHz 2 Core(s) 2 Logical Processor(s) I don't know what that means. Might as well be Hieroglyphics... What's my next step here? Give it to the techs and say change the chip? Run it until it dies then try to reflow the chip after letting some liquid flux drip back there? I don't even know what the hell it is. Is it the CPU, is it a graphics chip, are they the same thing? Talk to me...lol
 

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