precision001
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Last Activity: 05-07-2010, 06:45 AM
Joined: 09-21-2009
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Hi Precision, you want to sell leak seeker? my email is [email]xoring@hotmail.it[/email]Hi Precision, you want to sell leak ...ail.it[/email] -
Re: Laptop Motherboard Repair
Laptop drawing exactly half of normal current before power button pressed. No change after button pressed, no sign of life. What could this be? Bad FET? -
Re: VRM Mosfet replacement with non originals
Could you connect a bad mosfet source to drain to force it on? I observed a (functioning) gateway laptop once that had the source of one mosfet tied to the drain of the other mosfet in the pair. I believe they were 4407s. Does anyone know why this caused the circuit to work? How could I use this information to test mosfets on a motherboard?Leave a comment:
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Re: Laptop Motherboard Repair
The problem is figuring out what that shorted part is. I happen to have an identical board here, that has other issues. I have my new dark infrared station, so I'm going to remove and replace each part, one by one, until (hopefully) I find the bad part. It's gonna suck but, that's how you learn.Leave a comment:
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Re: Laptop Motherboard Repair
3 seconds then off? Sometimes reballing does the trick. But there are some cases when the gpu has nothing to do with it. I'm still trying to determine that myself.Leave a comment:
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Re: VRM Mosfet replacement with non originals
As far as testing them goes, for a P channel would I just measure resistance S-D(pos terminal on S) ? I have come across dead boards and found some mosfets measuring as low as 50 ohms. I presume they are bad - but there doesn't always appear to be any signs of damage - they look perfectly fine.Leave a comment:
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Re: VRM Mosfet replacement with non originals
I was wondering why do IC mosfets need 8 legs - 3 for the source and 4 for the drain? What advantage does this have? I'm thinking of experimenting with a board, and removing all but one pin for source and drain, just to see what happens.Leave a comment:
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Re: Laptop motherboard problem / Replacing capacitors
Be careful with heat guns. If it says "heat gun" - don't use it. You can damage, blister or delaminate your chip or board. You might hear a popping sound - that's called outgassing - moisture bursting out from the chip/board. It's not a good thing.
I'm using dark infrared now for BGAs because of too many problems with using air. Air is great for some things, small QFN chips like maxim pwm controllers, smps controllers, etc (I even use air for dc jacks sometimes)- but be careful when trying to reflow a bga. You...Leave a comment:
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Re: Gateway MA7 laptop won't charge or run off of A/C
There has to be a way to get around this problem. Maybe drilling through the positive hole on the motherboard, sealing it with an insulator of some sort then connecting the positive terminal of the jack to the next available positive point? To do this, you would probably need to take measurements from a working board to find out where positive comes out next. I see this problem a lot and am starting to get frustrated with it. I want to find a solution.Leave a comment:
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Re: Laptop Motherboard Repair
DV6000 No Power - Blue DC Block lights..
Low ohms
181 ohms - 7636 (By 8724)
51 ohms - 7636 (by ENE)
274 ohms - 6679 (opposite side of CPU socket)
Replace all? This version of the board uses an intersil SMPS controller. How would I test it? ISL6236Leave a comment:
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Re: Laptop Motherboard Repair
I replaced the 4825p mosfets, but the problem remains. One of the mosfets still shows shorted on all pins. I'm not sure where else to look.Leave a comment:
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Re: Laptop Motherboard Repair
If a mosfet is shorted, would it show zero ohms between all pins? I have another motherboard with no power, and found a mosfet with zero ohms between all of it's pins, so I think it's bad. It's labelled 4825p. I'm going to have to try to find a suitable replacement for that one. I wonder if there is a cross-reference guide of some kind for these. I'm going to do the same check for this DV6000, and check for shorts like you say between inductors and ground. If I detect zero ohms between an inductor and ground, what would be the next logical step?Leave a comment:
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Re: Laptop Motherboard Repair
I have an AMD based DV6000 motherboard in pristine condition. No power. No burnt mosfets, and no caps appear to be broken/shorted. When connected to a power jack, the LED indicator lights, indicating that there is no short, at least not in the beginning of the power circuit. Where would you recommend I begin?Leave a comment:
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Re: Laptop Motherboard Repair
How did you know that part was bad? What problems was the DV6k exhibiting? Was the repair successful?Leave a comment:
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Re: Laptop Motherboard Repair
Based on some information that I have collected, the unidentified 16 pin chip is a PWM controller manufactured by Intersil. That might explain why all the caps on the PCB opposite the CPU are showing shorted (with no power applied, of course). I wouldn't be surprised if the CPU itself is bad, but that's no big deal. The problem now is that I need to find another PWM controller, or this will never boot up again.Leave a comment:
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Re: Laptop Motherboard Repair
I removed the first burnt 8 pin mosfet. I can't read what type it is, but the top of it says ph7sd.Leave a comment:
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Re: Laptop Motherboard Repair
New information:
I was lucky enough to have another one of the same model come in, with a power jack issue. I took a close look. It looks the same, except that the 4704 isn't a 4704 but instead a 6690AS. The other 8 pin mosfet is a 4800B and the 16 leg chip is a 68CAZ (G801FG). I wonder if I can replace the two chips on the bad board with the same chips I read off of the intact board. I'm concerned that because the other Satellite P205 used a 6690AS instead of a 4704, that the other two chips may be different as well. I believe that a...Leave a comment:
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Re: Laptop Motherboard Repair
This one looks a little harder than I thought. I can read that one good mosfet is 4704 - the other is too damaged to read, but from what I can read, it doesn't match up to the 4704, so I think it is something else. I have no idea what the 16 pin chip is, but it appears to be damaged as well. I have measured zero resistance from the inductor visible in the picture to ground, and all of the small caps mounted on the PCB on the opposite side of the CPU are shorted....Leave a comment:
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Re: Laptop Motherboard Repair
I'm not sure how I should be checking voltages or what I should be looking for. Should I be checking the caps near the inductors? About the sound - it was almost like that of a relay switching on and off - in a very controlled pulse - almost like it was designed to do that.Leave a comment:
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Re: Laptop Motherboard Repair
I have an interesting one now, an Acer aspire. It powers on by itself but displays no video. Reflowed GPU - no effect. Pressed slightly on Max8760. Afterwards, board would beep one time each second. Strange beeping sound, almost like a blinker in a car - and I was unable to determine where it was coming from. Reflowing 8760 stopped beeping, but still no video. The 8760 is the dc-dc for the CPU, and the cpu is cold when power is applied. NB & GPU get warm, but not CPU. Could this mean that the 8760 is bad? I ordered some samples just in case. I checked...Leave a comment:
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