A number of parts are linked to this power rail including the cap cluster @ L7813. Would you have an adjustable power supply? Dial it up to 1V and as high current as supported by the power supply and use it to inject @ L7813 (with no power to the board). The shorted part should heat up and be visible.
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Personally cringe at the PMU ball size for rework. Flux and carefully lift up L7813. Then measure the resistance to ground again.
Which side is shorted? U7800 (PMU / producer) or downstream (consumer) side?Comment
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Short is at the downstream side.Comment
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Good. So U7800 is safe.
Inject again and review who heats up. Hope it is a cap.Comment
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A friend brought his fresh-from-ebay macbook pro A2141 after he failed replacement keyboard plugging.
I fixed all the little problems he introduced.
I am unable to install macOS to this device. Both Sequoia and Catalina (from Internet Recovery) start to install, but after ~2-5 minutes into the installation the macbook does a hard restart (max fan spin for a split second, then reboot without chime).
I noticed what I think is a very high power consumption, like 20V/1.7A when activating WiFi for internet recovery, and more like 20V/3.7-4.1A while downloading the recovery... -
I am looking at an A2337 and found this for the order of power rails and what they do. Can this be confirmed before I dive into hunting down power rails that do not exist or are not neccisary?
- PPBUS_G3H (12.6V-12.8V)
- This is the main power rail that supplies power to the entire system. Check this rail first, as it must be present for other power rails to work.
- PP3V42_G3H (3.42V)
- This power rail is derived from PPBUS_G3H and is used to power the SMC (System Management Controller) and other essential circuits. It should be present if PPBUS_G3H is working correctly.
- PPVRTC_G3H (3.3V)
- This
- PPBUS_G3H (12.6V-12.8V)
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Hi all
There's two other threads about this monitor with seemingly the same problem. The problem was resolved in one case by replacing the entire PSU board and in the second one by replacing an unknown IC.
https://www.badcaps.net/forum/showthread.php?t=50657
https://www.badcaps.net/forum/showthread.php?t=40512
The first one has pictures of the pcbs and I noticed that there's one IC and assorted caps not populated on mine (but the PCB itself looks identical) so I thought that'd warrant a new thread.
It's my dad's old monitor. He... -
Hi. Working on an A2141 that is power cycling. Powers up fine (20V @ 3.1A peak) -> fan spins ok and then at a higher speed (after we removed the trackpad so the sensors are missing) -> chimes ok but after the high fan spin -> power cycles and repeats this loop. We did manage to DFU the unit with revive mode (4/4 steps completed ok) -> resulted in a brief padlock graphic before power cycling. Unable to toggle the keycaps led since the boot does not reach this far of the cycle.
Q: Does the DFU process validate that the nand flash is OK ? We do not wish to restore this board... -
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...
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