Hi good Friends., today working on a Macbook Pro A2289, Logic board 820-01978-A. The history was liquid spill, Cleaned & replaced all corroded components & now the logic board shows 20v & .01amp on the meter. Not taking in any amps. Upon trouble shooting I get the required stable voltages 5V, PP3V3_G3H 3.3V but no PP3V3_S5. Checked the schematic, assume that this is generated from U7800. Checked all the Input/Output voltages on this chip. All is fine, except PP3V3_S5 is missing. Resistance from GND to PP3V3_S5 is 146 Kohms. First I need to make sure whether PP3V3_S5 is generated from this chip??? Thanks in advance
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What is the exact voltage to ground of PPBUS_G3H @ F7000? -
PPBUS_G3H @ F7000 = 12.61V (no fluctuations at all)... Do you think that this logic board has gone into DFU or Recovery mode as it's Pulling ~0.03-0.06A current at 20v from USB-C as measured by USBC meterLast edited by mferna14; 06-08-2025, 12:13 PM.Comment
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It could be but personally cannot keep up with the madness of each model as it varies with the direction of the wind. THIS model does require a charged battery to boot. Would you have a battery connected? Ghettoware.
reference:
https://boards.rossmanngroup.com/thr...harging.64804/
See post # 10.Comment
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Ok mon2., at last I figured out ths problem. This laptop had to be put in DFU mode & all restored back to factory default. Now at least I will remember that with 20V & drawing 0.03 ~ 0.08 amp, mostly it is to be rectified with DFU Mode. & one thing more for these models logic boards PP3V3_S5 will be missing & once restored all the require point with have 3.3V. Case done. Thanks dear for your helpComment
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Hi having similar issues with a similar A2289 model (661-14770). Does it really need a charged battery to boot? Mine doesn't seem to turn on using battery alone, and only turns on with charger connected.
I just want to clarify on your point, as mine only has the trackpad and fans working when I press the power button. Are you saying that to have it actually boot to the login screen, it would need a charged battery?Comment
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Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
Hi dear friends., I am working on a Apple MacBook Pro A1708 , Logic Board 820-00840-A that has no backlight. The logic board powers on fine, but no display. After Checking on the backlight driver chip, I found that the EDP_BKL_EN is missing. And this Power Enable comes from the PCH. So does this means this Logic board cannot be repaired & brought back to life again? The resistance from GRD to the test point of EDP_BKL_EN is around is 0.66M ohms. R8442 (0ohms) is ok. Any suggestion/Tip if any would really appreciate. -
Hi, this is my personal laptop, which the original board (lets call it Board A) blew up PU8700 (TPS51486), making a hole on the board, i had left the laptop at my desk one day with the battery fully charged and didn't touch it for a week, but when i tried to turn it on it didn't
Thought the battery was dead, so i plugged in the charger then tried to power on, the power LED blinked once, charged LED still orange, unplugged the charger, plugged in again and I noticed the "magic smoke" smell, so i unplugged the charger, removed the back cover and saw the blown IC (the "magic... -
Hi guys!
I'm trying to repair a TV that a friend gave me recently. Lightning struck next to his house and broke the TV apart from more electronic devices.
First of all I've checked the power supply and it works as expected. I removed the logic board and shorted the 3.3v standby output to TCON_ON and POWER_ON and every voltage was generated as expected (12v and 25v for logic board and 32v for TCON).
When trying to boot the TV normally (having the board connected), the TCON_ON signal is not generated from it which made me think there's some issue in the logic... -
I hope this is the right forum to post in despite not technically being a repair, but still a question of swapping boards.
I thought I'd explore the possibility to upgrade an existing working Samsung ue55nu7096u with the logic board (and power board if needed) of a newer model (ue55ru7105k) of the same size and appearance (and resolution). The reason being I'd like the extra inputs of that board including component in, an extra HDMI port and bluetooth. Its panel is broken so I have no use for the board otherwise.
The models launched in 2018 and 2019 respectively....
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