Re: Blown Mosfets - Worth it to fix?
Great advice. Thanks.
This motherboard's symptoms are high cpu and case fans on power up, but no other indications of life. Power led on board does light.
No Dell diagnostic lights are lit.
No heat from the cpu (with unplugged fan).
No heat from the chipset.
No video response at all (tried two cards) no onboard video on this board.
Are caps the typical cure for these symptoms?
Richard
skyking421
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Last Activity: 03-02-2016, 01:28 PM
Joined: 04-01-2011
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Re: Blown Mosfets - Worth it to fix?
Mockingbird,
Thanks for the advice. Here are the diameters.
Black caps are KZJ 6.3v 1800uF - about 7 or 8 mm diam.
Brown caps are KZG 16v 680uF - about 10 mm diam.
I have already ordered the Opti-mosfets, so I'll install them and try again.
Do these caps degrade to the point of causing that damage to the mosfets?
The mosfets are rated at pretty high amperage.
Am I risking blowing out the new mosfets?Leave a comment:
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Re: Blown Mosfets - Worth it to fix?
Mockingbird,
Yes the Black caps are KZJ 6.3v 1800uF and the Brown ones are KZG 16v 680uF.
They are not swollen or leaking. (yet).
I know it's not a proper test, but I used the ohms scale to test them for shorts or open. Also took note of the capacitive charge/discharge swing of the needle.
Of course they are still "in circuit", but they all read similar values, when comparing paired caps.
Maybe they are all the same amount of "bad", but isn't that unlikely? Or is it?
Do we...Leave a comment:
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Re: Blown Mosfets - Worth it to fix?
Thanks for the advice.
I'll check those caps!Leave a comment:
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Blown Mosfets - Worth it to fix?
Hopefully, I will get my photos in here. (attached)
I'd like to repair this Dell XPS 710 motherboard, that I got not working.
I don't see any swollen caps, but these two mosfets were nuked.
They are cheap enough, so I ordered some from Digi-key.
My question is, am I right in assuming that these burned up from some direct short the previous owner did? They may be used as voltage regulators, but I may be way off with that idea.
Any ideas why these burned up and what I might do to prevent the next ones doing the same?
They are labeled as 79n03s and there... -
Re: Macbook Pro 13" No Power (another one)
I measure 2.6v dc on the missing component connected to pin #3.
And 0v on the other side of the missing component space.
Any help?Leave a comment:
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Re: Macbook Pro 13" No Power (another one)
I'm having a hard time trying to decipher the datasheets.
It looks like my "resistor" is connected to pin#3 (vref) of the chip, but another datasheet rotates the thing 90 degrees and confuses me as to which pin is which.
Usually pin #1 is at the "dot" on the chip. Right???
Anyway, if this is pin #3, then it has a .22uF Cap connected directly to it.
Pin #2 has a 20k resistor.
Can I verify anything by measuring a voltage there?
Thanks much.
Richard...Leave a comment:
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Re: Macbook Pro 13" No Power (another one)
Thanks.
I'll start looking at that.Leave a comment:
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Re: Macbook Pro 13" No Power (another one)
Just by chance, I see a tiny resistor (?) is broken off the motherboard.
If I did it, then it's an additional problem.
I don't think I did it, so maybe this is the whole problem. I bought this laptop like this.
It is part of the circuitry for part #51125. There are other resistors also connected to #51125.
It's clear to see in my photos attached.
I'm willing to try soldering a microscopic piece on again, if I can find a replacement. I do have a number of motherboards around that I could get...Leave a comment:
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Macbook Pro 13" No Power (another one)
I have another one of those 13" Macbook Pros (2010) that have no power.
Pressing the power button does nothing. No fan spin, lights, nothing. I have checked the power button operation (pins 5 and 29 on the keyboard socket) and it drops the 5v on pin 5 to zero when pressed. I guess its working.
The fuse near the power plug is good as well as the other 3? green fuses.
The charger seems to work normally. Green, then orange, then green again, showing a charged battery (I guess). Tried two chargers.
I get an occasional 19v at the battery. It...
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