Kervin Mathumbu
Member
Last Activity: 10-12-2024, 05:29 AM
Joined: 02-21-2024
Location: Nzhelele (0993)
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Cell phone shop makes a lot of sense and they are several around.... -
Noted and yes, we have mouser here. I shall take a photo from the working board in the morning. Had a Lenovo T420 I could check. Just that I own no hot air system. So I would still need a tech shop to cleanly remove it for me. So, depending on shipping costs, odering through mouser may still be a valid/cost effective option.
P.S Sorry no, the mosfet is not ordered just as yet.Leave a comment:
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This makes good sense. I see I had missed the gist of that stackexchange QnA then
Seems I, at best, should leave the machine alone until I have a replacement mosfet. I have a 5yr old autistic who colonizes the other machine (which I should use for my games and apps dev work). I should hopefully have the mosfet at month end. Another bucket full of gratitudes for you for the shared insight.
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Tons of thanks to all of you guys - more specially Sir [USER="295753"]mon2[/USER] who walked with me (a newbie) from start to bingo with handy pointers.
Short version: Laptop now working with a bypassed mosfet (yes, I understand the inherent risk and can only hope in God's mercies and goodness that the spare part will find the laptop still in one piece).
Long version: After failing to cleanly remove the mosfet with a soldering iron and added solder, I had to carefully scratch up the black part of the mosfet with a pin, and broke it further with a long nose....Last edited by Kervin Mathumbu; 07-18-2024, 08:17 AM.Leave a comment:
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Trying to take it out...
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Smaller mosfet has a reading of 02.0 when set to 200 range. Bigger mosfet will only have a reading from 200k range - counting up front around 35.0 going up....Leave a comment:
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To the best of my recollection the meter (in resistance mode) would not display a reading for any of the two mosfets unless I set it to 200k or 2000k but I shall retry this to confirm. Post#14 was done in diode or continuity mode but I see I went on to infer to the readings thereon as resistance (instead of voltage drop?) in some of my succeeding posts (my bad - I am admittedly a newbie in these, trying to fix my own mobo). As suggested, I shall retry measuring at a 200 range first and then feedback.
[USER="328836"]Sephir0th[/USER]
Yes, those are the mosfets I am testing....Leave a comment:
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When set to 2000K resistance range, the 1st mosfet counts up to about 730 (it seems) and then start counting back slowly. The 2nd mosfet counts back from around 050 to 000 within some 2 seconds or 1 and then stay there. The screen will show 725 for example with no decimal at all. It is the cheap DT-830B so perhaps it is very limited....Leave a comment:
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Sorry let me go through your directives again. I actually thought I got them all. Should post back shortly....Leave a comment:
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With my meter function set to 200k res range, the first mosfet keeps counting up (was near 200.0 at some point). The 2nd mosfet start from 01.0 and within a second or so counts down to 00.0
Assuming the 2nd mosfet is shorted?
if so, can I temporally jump it until I have a replacement? I understand it could be risky but I am to run the PC without a battery (since they both last locked up after years of use) and so I hoped it could perhaps work to my advantage somehow. I will understand if the battery's absence will on the other hand only amplifies the risk - and gladly...Leave a comment:
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1st bigger mosfet is part number: [B]PQ8901[/B]
2nd mosfet: PQ89021st bigger mosfet is part number: [B]PQ8901[/B]
2nd mosfet: PQ89021st bigger mosfet is part number: [B]PQ8901[/B]
2nd mosfet: PQ8902Leave a comment:
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Okay I was measuring in diode mode. Let me do in resistance mode. You right it looks like a hole but actually a marking or so. The picture I shared is from someone here who had a bad battery case. So his tantalum had that hole-like mark and so does mine it appears....Leave a comment:
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Sorry I had missed your reply. The tantalum looks clean but I have some findings you could make something out of.
I have now located both mosfet near the said resistor. One that is further from the currency sensor have 18v going into it. But has a 3v at the gate. Therefore what should be the 2nd mosfet has 3v at source and 3v to gate. Might this mean a shorted 2nd mosfet?. I shall get the part numbers from the schematics. My wife has a clever camera phone but I do not. The 2nd mosfet is the same one with odd resistance of 0.02Leave a comment:
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Tested the same tantalum on my working laptop and also got no reading. So likely I am not testing it correctly I also tested the pin4 resistor and got the same 3.9 reading. And there is 18v passing through it unlike my broken board which only has 3v. Also the mosfet on the working laptop has 23.9v at its gate. Unlike my broken one which has 0.09v
Where might I go from here. Or how am I to best test the tantalum from my DT-830B meter?Leave a comment:
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With my meter still on 20k, I get no reading from the tantalum cap. Or might I have configured my meter incorrectly? Someone said to could test by shorting the cap as well. I plugged the AC and then short it accordingly but got no spark at all. Might this confirm that the cap is bad as suspected? What seems to be an equivalent replacement is near $2 at my local mouser I found....Leave a comment:
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With the help of the schematic for board R3.1 (mine is R3.0), I located the said resistor near the charging jack. Interestingly, it is near the mosfet that had 0.02 on source and drain. And 0.09 source and gate. With my meter set to 20k resistance, I get 3.94 reading. Is this equivalent to the 4k expected or it's way off?
I am now trying to test the tantalum cap and should feedback on it as well.Leave a comment:
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Should retry the gates and pin4 in the morning. They all seemed to have 0 resistance essentially. Except one that starts with a sort of resistance but also quickly goes to 0.Leave a comment:
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Struggling to locate the suspected mosfet pair in short now. Tested a number of mosfets gates but none has a clear continuity to or from pin#4 of my BQ chip. And none shows a 19v input of those mosfets I tested. Feel a little stuck but should continue to acquaint myself more enough these components so that I can make better sense of the guides and suggestions I am receiving from you guys.
pin#4's track sinks to the other side shortly after extending from the IC. With no easy way to track how it continues from there (seems like a dead end of a sort) to hopefully locate the series ...Leave a comment:
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Measured the same mosfet on my working laptop (identical model) and it reads 530 source and drain. And no continuity for source and gate. Might it be a defect mosfet case or some nearby component that feeds it?Leave a comment:
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Two mosfets by the IC are
475 source and drain (and around 16k source and gate)
461 source and drain (around 13k source and gate)
I have one mosfet near the charging jack wi 0.02 source and drain and 0.09 with source and gate. Might this be the culprit or I possibly confused things?Leave a comment:
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