Unit arrived with a common issue among INTEL Dual Core units. Powers on then shuts off immediately. Though there can be several causes of this symptom, usually the case is 'cheap'/bargain ceramic capacitors. When shorted they can also short the AO4914 chip shown in the center of the Zoom-Out picture. In this case the cap marked with the red X is shorted. When removing it split in two horizontally. The two caps on the on the other side has also been known to short previously. This can also lead to NO Charge, or never reaching 100% charge, or Working on AC but not on battery. So on the Intel models I check all the ceramic caps in the Power In section first. (well at least after a visual of USB ports and other obvious problems- power plug/charger etc...)
Steps Taken:
Check Ceramic caps in power in section
Locate shorted parts (also checking AO4914 Dual Channel MOSFET)
Replace capacitor
Test
Reassemble
Test Again (also with battery in)
Start Windows (XP or Win7) check battery levels in Control Panel or BIOS
Allow battery to charge.
15 comments:
Power in section means DC IN? what you say about AO4914,that also short or not?If this MOSFET is in DC IN section then the unit ca run on batter?because the battery area is save, only here the damage is in Dc in section.
if you say ceramic cap is break then what you get on ohms?short or open.you say short.but this is an open condition.also how you check the short MOSFET.i am thinking that on ohm meter it gives infinity on both side pins.is this right?
Asif: The short condition is less than 10 OHMS when it should be infinity.
An open condition is infinity in both directions.
The MOSFET has 2 Drain and 2 Gates
And may have 1 source or 2 depends on model. The MOSFET is good since the POWER IN and charge circuit works now.
Note: I do not keep track of measurements, I only test and observe (or replace) bad parts, not annotating the resistance levels by what the measurement is. That would be Reverse Engineering (something that I don't want to do).
Thanks for ansewring.About MOSFET i wants to ask that how you check the input and output voltages of an MOSFET IC.i know with a volt meter but how you identify that its input is ?V and output is ?V.is this done by a datasheet or how.
ASIF: Set the meter to the Diode mode, and verify current is able to pass through. This is done with no battery, and no power connected.
That is from basic electricity class.
i wants a suggesation,Someime when checking a laptop i don't have its exact charger and battery,so if i make a DC supply device(Same like for mobile phones)then is it possible to power ON a laptop with its help to connect its wires on the battery connector of laptop?
asifnawaz - it depends on the laptop. I've done this before with a variable regulated DC power supply (9-15v). In theory, all one needs to do is supply the proper BATTERY voltage (important since most laptops don't pull 19v from the battery side but instead use 11.1 - 14.4) to the battery input side of the laptop along with your power supply's ground. The trick is with some laptops that require a signal handshake with the battery so the Maxim or TI controller will supply output to one of the mosfets. I haven't run into such an animal yet but I've heard of horror stories from other tech's I know who have so be very careful when doing this. I'm sure this can be very risky
congratulations for your blog, i m electronic technicians and ex sony chile technician and i repair laptop,hp,acer,asus,sony,so sorry for my language but i dont speak english but i understand so good,if you need help,here i am,thank you.
Hi
I have same problem but just with hp g6000/compaq f700 AMD mobo.
when I push power button lights turns on and straightaway turns off. After many times of pushing pwer btn its sometimes turns on fan (nothing on sreen) and then turns off. I disassebly it clean it, no burn marks seen, put it back and was workin for 10-15 min then all same prob as before.
battery charges not turns on from it as well, changed RAM, reseted CMOS. no result.
mrko: It could be almost anything in your case. From power problem to BIOS problem. If it runs for 10-15min it may be a heat problem, dry thermal compound, fan or blocked vents on heatsink.
If battery not charging, check MOSFETs in front end (DC IN)
Welcome elandresin- Sometimes I get behind.
Just found your blog Mayo and it has helped me identify the possible cause of my Dell Studio 1537 power failure.
So thank you very much for that!
asifnawaz: I keep a laptop adapter with no plug on the end and I save the plug ends from dead adapters. Usually I can find a plug end that will fit whatever laptop I'm doing, and splice it onto the adapter. If I can't then I solder the adapter wires to the motherboard at the powerjack. Be careful though, watch the polarity and voltage!
Most cell phone adapters can't supply enough current to run a laptop, and the voltage is too low. I would avoid connecting to the battery terminals.
NG: I've done the same thing, and made a 6 wire 'pigtail' connector with various laptop plugs on them. DELL, ACER, Gateway, IBM, HP, generics and one Male connector. The adapter is a 4.74a. The reason for a male connector is that sometime I may have to use 6.3amp for older large laptops and can plug them into that for more current.
Post a Comment