Trying to determine whether I have shorts on this board or not. PU500 and PU600 are removed. Have lifted coils PL500 and PL600 after measuring 45 ohms on 500 and 65 ohms on 600. 45 ohms measured at pad "2" of PL500 (p. 47). 65 ohms measured at pin 8 of PU600 (p. 49). Are these considered short?
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Re: LA-824 cold checking for shorts
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Re: LA-824 cold checking for shorts
A short is something that can be considered a significant load on that voltage. Basic Ohm's Law. For instance, lower than 20 ohms on 5v could be a short. Lower than 10 ohms on 3.3v could be a short. Lower than 3 ohms on a Vcore rail could be a short but this is not always the case - Ivy Bridge CPUs read ~1 ohm on the Vcore rail.
Generally speaking, shorted capacitors will be a dead short (very close to zero) while semiconductors like MOSFETs or ICs will have some resistance, maybe 1 ohm or 2.A working TV? How boring!Originally posted by PeteS in CAComment
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Hello:
I have both these laptops that appeared to have the same fault so I thought I would have a go at replacing the PCH as something to learn, they both are using the same PCH.
I started on the ACER:
Up on connecting power no signs of life but current is consumed from the bench power supply and the PCH is hot.
All the caps on the top of the PCH are showing 0 ohms and the 3.3v rail is shorted.
I followed the videos from Sorin, Electronics Repair School on Youtube heating from the bottom to install. I practised on around 10 scrap... -
hi all,
first of all: i'm a (motivated) newbie, so please forgive me any stupid question i may or may not ask
i'm currently repairing a projector: Epson EB-U42 that doesn't start (no lights, nothing).
what i've found so far:
- the PSU does its job and supplies 12V to the mainboard via the connector.
- shortly thereafter, there is a mosfet (TS420-600B) where i can test 12V on the one side (in the data sheet this side is called Anode), Gate 0V, Kathode shorted to ground
- not far away, there's the first cap with a resistance of 0.7 ohms.... -
Hey, I'm currently working on a Chromebook.
Not turning on, no LED, power button= no reaction, USB-c charging cable plugged in shows 5V 0,00A.
While checking for shorts, I noticed 13 ohms to GND at a coil (5V rail).
I removed two resistors and the coil to locate the possible short. It turns out that the output of U43 drops from 143K to 13 ohms as soon it gets voltage on VCC.
VIN1 und VIN2: 12 V 3V3LDO: 3,3 V
BST: 3,3 V
EN and OUT 0 V
none of them less than 80 ohms except GND of course
That doesn't sound right to me. I hope someone... -
Hi this is a really odd case.
I have removed all of the esd ic for USB 3.0 and 2.0
I measured all of the data lines and 5v usb voltage lines there are no shorts
all of the USB ports have no damage
Clearing the bios using the jumper wont help.
it is still showing USB overcurrent device
the only temporary fix I've tried and worked so far is flashing the bios
and the error is gone
but when you start the motherboard with a USB device still attached
the USB over current device error is back. the bios needs to be externally flashed... -
Good day, I need some assistance with this laptop. It came in with no power after a liquid spill. The device was very dusty and one of the inrush mosfets exploded, the other was shorted and of course a shorted 19V power rail. I replaced the following defective components to clear the short:
PQB4 (AON7380, this one blew up, pads needed to be rebuilt, no vias)
PQB3 (EMP21N03HC, this one was shorted)
PQB1 (L2N7002WT1G, burnt and cracked)
PUV2 (QD9619AQR1, shorted)
After replacing these components and checking to make sure there were no shorts, the laptop powered on for...
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