HP envy i7 laptop won't boot

[edugimeno]

Hi there!
i have owned this laptop for at least 10 years but It's still way powerful as I bought a little above my required specs, so it was working like the first day and it had all In needed.

Then suddenly today, this happened

• It was on battery (too aged) anew went to hibernate due to low bat
• I plugged the power supply to it and clicked the power button to de-hibernate it
• It came back up but was irresponsive to keyboard or mouse and the mouse flickered to all black every 4 or 5 seconds and then back
• I had to forcedly turn it off holding the power button for some time
• After that I won't start again. Nothing changed after I removed the charger of after I had the battery out for more than 1h, and left all capacitors discharge

Symptoms now are, the pwr button light goes on for a small fraction, CD motor STARTS to spin but stops faster than usual and pwr led goes off. This cycle repeats forever. PWR light only stays on for less than half a second, then all goes off and then retries and retries

Any idea on what to look at? I haven't disassembled it yet as I'm out of home for a week and I don't even have a screwdriver with me but I'd like to see if this sounds familiar to anyone, just to start figuring out...

Thanks in advance!!

[edugimeno]

Ok I found some screwdrivers today and opened this laptop
I starting detaching all peripheral sockets one by one and also both ram modules too and testing in between all steps. No luck. I ended with only the mb and the pwr cable, and it still shows the same symptom

I found these board online (day11amb6e0 rev e with i7 4510u) but too expensive for what they are

Does anyone have any knowledge about this issue or have any pointer on what to start checking?

Thanks a lot!

[mcplslg123]

The schematic and boardview for this motherboard is already posted in this forum. Search and download them to begin with.

You need to follow basic steps to troubleshoot and a multimeter is a must.
01.Measure resistance to GND on all big grey coils.
02.Check AD_ID voltage
03.Check RTCRST#/SRTCRST#
04.Voltage on pin1-4-8 of dc-in mosfets.

[edugimeno]

Thanks I found the schematic
Before I found your reply I already tested something and it's weird...

Under the VGA ic, Nvidia, theres a bunch of small capacitor around a larger yellow cap labeled c79, I measured across this one with no power and it had 25ohm to gnd. Seems too low. It drives the +vgacore voltage.

I checked this voltage while DC was in the charge plug and mb was trying to boot up and it was pulsing from 0 to 900mv until one time where the power stayed up.

After several tries I realized that it does continue to boot up (nothing connected to MB to I can't really check what's actually going on or not) as soon as I touch the +vgacore with my multimeter points. How could this be? Something related to fooling the gpu_core_sense?

Weird...I may solder a wire to this one and plug it all back in and see if the screen actually comes back

[edugimeno]

The schematic and boardview for this motherboard is already posted in this forum. Search and download them to begin with.

You need to follow basic steps to troubleshoot and a multimeter is a must.
01.Measure resistance to GND on all big grey coils.
02.Check AD_ID voltage
03.Check RTCRST#/SRTCRST#
04.Voltage on pin1-4-8 of dc-in mosfets.

Also specifically replying to your comment:
01: pc147 is 14ohm, pc154 is 24ohm, pc159 os 18 ohm
02: ad_id: 0,6v
03: rtcrst and srtccrst can't find a place to test them, I see them at the sch but I can't find a physical pad to test them
04 DC in MOSFET:19v, 24v, 19v. I can't find any more MOSFETs. This one is the only MOSFET I can see by the ps area

Thanks!!!

[mon2]

Review other mosfets that will be in an 8 pin package where (often) source pins = 1-2-3; gate pin = 4; drain = 5-6-7-8.

[mcplslg123]

The resistance at C79 is correct as its expected to show low resistance. Note that cpu/gpu area will always show low resistance to GND. Since the mb is switching with 900mA current draw,there cant be any issue with RTC circuit like RTCRST#.So you can ignore this part.DC-in mosfet voltage is also correct.

Measure voltage on all big grey coils when powered on.
Check DRAMRST# is present or not on pin30 of ram slot.

[edugimeno]

The resistance at C79 is correct as its expected to show low resistance. Note that cpu/gpu area will always show low resistance to GND. Since the mb is switching with 900mA current draw,there cant be any issue with RTC circuit like RTCRST#.So you can ignore this part.DC-in mosfet voltage is also correct.

Measure voltage on all big grey coils when powered on.
Check DRAMRST# is present or not on pin30 of ram slot.

I got it to power up with the trick of moving stuff around c79
voltage at coils:

• around ps input I get 1.4v and 3v
• Close to CPU and VGA I get all three coils 0.9v
• Close to USB ports I get 3.3v and 5v. But close to this last one, c747 has 0v across....all the other large caps have the same voltage as their neighbor coil

Is there and easy and safe place to probe dramrst?

I don't have a thermal camera but by touching I can't feel any overheating area ..
thanks!

[edugimeno]

Very weird now: I realized that in order to get it to continue booting (not really booting, read below) it's not actually about messing with the multimeter around c79 but about pushing over the back side of the area between CPU and Nvidia IC (middle point between both heatsinks arms)
I may be wrong but this sounds to me like reflowing?? Which I can't do as I don't have the proper gear...

When I say continue booting I mean that the power led stays on all the time, the fan keeps running at different speeds, and I can hold the pwr button down for ten seconds for it to shut off properly. But I don't see a real boot as I tried this all again back into its case and connected to ram, hd, LCD, battery and everything and no signs of life...LCD stayed off as if nothing was connected to it.

Is it still worth this repair?

Thanks!

[edugimeno]

ANyone? Im about to throw this motherboard away...

[mcplslg123]

Patience is the key in laptop repair. You are only telling us the behaviour/symptoms of the mb but there is no measurements. A mb will post after all its requirements are met.

First,confirm whether its posting at all. You can connect a usb keyboard and check whether numlock light glows on toggle. Dont connect anything else like hdd,screen etc.

If not posting,then proceed to measure voltage on all coils and mention their markings so that we can understand what is miising.

Lastly you can throw the mb if you so wish as it belongs to you.

[edugimeno]

Well I did post some measurements on an earlier post, but didn't check the USB keyboard.
It's definitely now doing the normal boot process because usually the fan would start and then stop after 2 seconds, and in this case the fan starts, then after 5 s it goes double speed, and later it goes even faster and stays there at top speed forever. Having RAM modules and HDD connected didn't improve this.
I have found a second hand almost equivalent (but DV7 instead of m7 variant) Envy-17"-i7 and Im waiting for it to be delievered. Not trying to swap MB, as they are different, just keeping this one for me and selling the other in parts (everything but MB)

Thanks

[mcplslg123]

Need clear answer to my queries on post#11