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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

03-08-2023, 02:11 AM
Re: 820-3330-B suddenly doesn't power up

the resistance between pad #2 of the fuse to inductors L7510, L7520, L7530, L7550, L7560 is around 25-30 ohm, while the resistance to the graphics chip inductors (L8930, L8960) is a poor 1.1ohm. I had problems with the graphics chip before it went dead... So i should guess the nvidia chip is toasted.

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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

03-07-2023, 09:25 AM
Re: 820-3330-B suddenly doesn't power up

So, nothing going on... the board draws 0.5amp at 1V... everything is stone cold...

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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

03-06-2023, 01:56 PM
Re: 820-3330-B suddenly doesn't power up

So finally I have the option to get at this problem. It took a while, but in between jobs (regular and extra) and searching and trying to get a house, not to mention all the calculations and visits at the various banks, led to a delay in this reviving project.

So today after work I connected two wires, one is soldered to the ground point (one of the many big pads under the screws) and one is directly connected at the two pads on the consumer side of the two fuses. Should I only connect to pad number 2 only of one fuse? But I...

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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-01-2022, 03:23 PM
Re: 820-3330-B suddenly doesn't power up

the resistance to ground on both fuses on pin 2 is 22-23 Ohms.

On the consumer side (pin 1) it just rises... got to 22M Ohms and still counting...

I have an adjustable power supply at work, might use it after hours during week. Maybe I could also borrow it on the weekends, but this one is packed like hell... So it will have to wait.

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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

12-01-2022, 03:02 PM
Re: 820-3330-B suddenly doesn't power up

So now with fuses removed this are the measurements:

On pin 1 of both fuses (F7040 and F7041) I get 12.57V.
On pin 2 it's 0.25V.

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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

11-30-2022, 04:25 PM
Re: 820-3330-B suddenly doesn't power up

Just before going dead, the CPU and the integrated GPU (intel) were doing allright. It all happened when i reset the NVRAM and got the nvidia GPU going again. Before resetting NVRAM i was messing around U8900 with the soldering iron. But just checked again and there is no short done by me on the IC.

I will remove the fuses and check again.

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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

11-30-2022, 04:14 PM
Re: 820-3330-B suddenly doesn't power up

PPBUS_G3H is only 2.24V

Also is worth mentioning that CPU and GPU are quite warm, not hot, can keep my fingers on top of heatsink.

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Last edited by hypergl; 11-30-2022, 04:16 PM.
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hypergl replied to 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

11-30-2022, 03:45 PM
Re: 820-3330-B suddenly doesn't power up

Ok, with some help from Louiss Rossmann's youtube channel and some logical thinking and path following... got to the point where I have a short on U7000 between pin27 and pin28... which also translates to short on R7020.

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hypergl started a topic 820-3330-B suddenly doesn't power up

in Troubleshooting Laptops, Tablets, and Mobile Devices

11-25-2022, 02:46 PM
820-3330-B suddenly doesn't power up

I had problems before with this computer. It was crashing while booting up, when the bar was halfway up, it rebooted and stuck in a loop, with no backlight or screen.

Found that it might be because of bad solder on U8900 so I used some script magic to disable the nvidia gpu. Yesterday got myself finally the right soldering tip and put some fresh solder on the U8900.

After soldering, checked like 15 times that everything is ok, no shorts.
Turned on the computer. It boots, it works. Without the nvidia graphics disabled.

Moment of truth, did the...

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hypergl replied to 820-3330b board with no image

in Troubleshooting Laptops, Tablets, and Mobile Devices

04-27-2022, 10:20 AM
Re: 820-3330b board with no image

Finally I found the problem... It was not a Cap or Coil... It was U8900, so the chip delivering the power to the discrete graphics. Found a script on how to disable the Nvidia graphics and I also set Csrutil to disable. Right now I'm using the laptop only on integrated graphics and it's working just fine. Maybe someday, if I have the need to, will get myself on changing the U8900.
Thanks guys!

M

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hypergl replied to 820-3330b board with no image

in Troubleshooting Laptops, Tablets, and Mobile Devices

02-03-2022, 03:23 PM
Re: 820-3330b board with no image

So, got a little time today and measured the next things.

[B]Q9607:[/B]

pin 1 - gnd
pin 2 - 3.3V
pin 3 - 3.3V
pin 4 - gnd
pin 5 - 0V
pin 6 - 0V

[B]R9676[/B]

pin 1 - 3.3V
pin 2 - 0V

[B]R9678[/B]

pin 1 - 0V
pin 2 - 2.6V

[B]R9671 to R9674[/B]

pin 1 - 3.3V
pin 2 - 3.3V

[B]L9621[/B]

pin 1 - 0V
pin 2 - 3.3VRe: 820-3330b board with no image

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hypergl replied to 820-3330b board with no image

in Troubleshooting Laptops, Tablets, and Mobile Devices

02-01-2022, 05:17 PM
Re: 820-3330b board with no image

It might just be, since in the last year I could not power a single optical mouse on one of the two USB ports... Can't remember which one, but will try to... ...

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hypergl started a topic 820-3330b board with no image

in Troubleshooting Laptops, Tablets, and Mobile Devices

02-01-2022, 03:05 PM
820-3330b board with no image

Hello everyone.

My own macbook pro from 2012 just decided it had enough. There is no image on the screen (screen dead, no backlight, no image whatsoever even with a torch behind the apple logo), there is no image on external via thunderbolt/DP adapter.

There is chime though, there is also all the controls from the keyboard, so it is possible to control the backlighting of the keys.

I had problems for the past year or two with the display, showing a green line (single pixel) or two, maybe three. But nothing that I took seriously as I had always used...

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hypergl replied to New Members - please post your introductions here

in Announcements & Related News

01-09-2022, 04:03 PM
Re: New Members - please post your introductions here

Hi to everyone, newbie here!

My name is Martin and I work as a technician. Kind of a rookie, but I learn fast i guess...
Right now I am repairing old PC boards (from the 80s and 90s), which is kind of easy...
The challenging tasks i got myself into are finding faults in my grandma old maranty stereo amplifier and mostly finding the reason why my macbook pro doesnt show any picture at all.

Hope will learn something from all of you and that I could solve the above problems.

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820-3330-B suddenly doesn't power up

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820-3330b board with no image

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