So I have had several Acer 7736z laptops with a shorted U60 mosfet lately. Some of the new mosfets have shorted immediately after I've replaced them, some of them are still running. I would like to find a more robust version of the same part. The part I have been using is a SI4812BDY-T1-E3CT-ND. Anybody know a better replacement?
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Re: SI4812BDY-T1-E3CT-ND more robust version
Are you taking proper ESD precautions?shorted immediately after I've replaced them -
Re: SI4812BDY-T1-E3CT-ND more robust version
With the first two that died, yes. Plus, they lasted for a few days each. The last one that died I did not. It was on a board I picked up off of ebay. Lasted all of about a second.
Whatever this defect is I'm guessing it may be caused by a bad SMD chip somewhere up the line, but I can't find it and most of the time the laptops seem to work fine after a MOSFET replacement. I'd like to find a new fet with the same specs but less sensitive.Comment
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Re: SI4812BDY-T1-E3CT-ND more robust version
The effects of ESD damage don't always show up right away.
How they end up shorted can give a good clue as to whether it's ESD or not --- if the gate is shorted to source/drain that is a very good sign of ESD puncturing the gate oxide.
Looking here you can see all the Vgs don't go over 25V so you're unlikely to be able to get a "more robust version".Comment
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Re: SI4812BDY-T1-E3CT-ND more robust version
Source was shorted to drain on every one. Gate was closed. This happens on every MOBO in this laptop I've had to repair so far. I was unsure if maybe I should get a replacement without the schlottky diode? Maybe one with a higher amp diode?Comment
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Re: SI4812BDY-T1-E3CT-ND more robust version
In other words, there's infinite resistance between the gate and source/drain, but 0 resistance between source and drain (both ways; remember a normal one has a body diode)? That suggests a drain-source overvoltage. You could try one with a higher Vdsmax than 30V, but the diode is mandatory and intrinsically part of all MOSFETs.Source was shorted to drain on every one. Gate was closed.
This document has some interesting pictures and discussion:Comment
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Re: SI4812BDY-T1-E3CT-ND more robust version
Precisely. Yes, it goes both ways. This suggests to me that the diodes are being severely overpowered. I was thinking that one higher than 7A (I think that's what my replacement used) would be better at preventing this from happening in the future. What do you think?Comment
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Re: SI4812BDY-T1-E3CT-ND more robust version
I'm thinking about using this one instead. Thoughts?
http://www.mouser.com/ProductDetail/...KZgFl3gEhVI%3dComment
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Re: SI4812BDY-T1-E3CT-ND more robust version
That has a higher current rating and lower Rdson, but if the previous ones died of drain-source overvoltage (inductive spikes? this is a laptop so the PSU is already around 20V, 30V isn't much higher) then it won't be any different - this one is rated for 30V too.Comment
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Hello everyone, I recently found this badcaps site and super Learn Electronics Repair youtube channel. And I wanted to learn how to troubleshoot power supplies and VGA cards and how to practice soldering, since I already have a properly defective piece of them. I am currently trying to solve two problems:
I have a Gigabyte GV-RX460WF2OC-4GD type card. I managed to find the faulty MOSfet (AON6414A) on it, which I replaced. The card starts up, but after about half a minute, the MOSfet in the same position will be shorted again. Is it possible that the PWM controller driving the MOSfet... -
I've got an old Alienware M18x R1 which shorted out the charger whenever it was connected. Tracked down the short to two shorted caps and burned CPU power controller caused by a shorted mosfet on the CPU's graphic power supply.
I've replaced the faulty mosfet, two shorted caps and the CPU Power controller (NCP6151S52MNR2G).
Issue is now whilst there is no short if I attempt to power the system on the fans spin for a couple seconds there are no lights and no further action - the PCH is heating up but there is no CPU power coming out but there is an enable signal... -
I am trying to fix an iMac 2017 PSU, initially came with a blown fuse and shorted PFC MOSFET (6R199P). After visual inspection and some measurements I replaced the FET with a P20NM60 and tested with 100w series lamp, and it lasted 1 second before going into dead short. The PFC controller chip (NCP1605BG) and its passives appear fine (passives measure OK), but I do not know if there is a simple way of testing the NCP1605 as I wouldn't like to blind-replace it.
There was some slight blackening of the solder on the PFC controller passives so I reflowed them all with some flux. I am waiting... -
Hi All,
I have this MSI GTX-980ti Gaming Golden Edition. It had shorted mosfet on memory. Replaced the shorted i.e. Q47 PK616BA with 4C09N and the card ran fine for a month. Then suddenly again the same problem. This time when i replace it 4C09N or with replacement PK616BA (Aliexpress) it gets shorted. As soon as turn on the PC the PSU shuts down and the same mosfet Q47 gets short.
What should be the next step. Kindly guide.
The board view files for this gpu is available and attached. https://www.badcaps.net/forum/showthread.php?p=1237952... -
I tried to use this method:
Testing an N-channel MOSFET:
Step 1: Discharge the Gate (turn off the MOSFET)
Place the black probe (COM) on the Source (S) and the red probe on the Drain (D). The multimeter should show no continuity (high resistance or "OL" – open line).
Then, touch the black probe to the Source (S) and the red probe to the Gate (G). This discharges any stored charge in the Gate, turning the MOSFET off.
Step 2: Charge the Gate (turn on the MOSFET)
Now, place the red probe on the Gate (G) and the black probe on the...09-27-2024, 03:31 AM
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