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Re: Mosfet Power dissipation question
I know you have blown the MOSFET's when you shorted the leads together so now you have new MOSFET's so why can't you adjust it be within the spec? It has 100mV offset right now, correct? Unless I read the whole thing wrong. Or are you saying you blown the NEW MOSFET's when you try to adjust the offset.
BTW, since NE is obsolete, hope the NE you find is not faked.
https://www.mouser.com/ProductDetail...%252BE9Q%3D%3DLast edited by budm; 05-15-2020, 12:09 AM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: Mosfet Power dissipation question
Yes the new NF replacement I blew also. The original I blew touching the speaker cables and the NF I blew by touching the DC offset leads!
I have found a source who claims to sell originals. But as mentioned I need to understand this Power Dissipation thing before I decide on the transistors as I'm worried about the heat producedComment
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Re: Mosfet Power dissipation question
Try checking the idling current sensing 2 Ohms resistor and Diode of the blown channel (I do not know which channel was blown) R321/D305(L) and R421/D405 (R) to make sure they are not damaged. At 180mV of bias setting, the idling current will be 180mV/2 Ohms = 90mA. May be the value of the resistance has gone down so to get the 180mV reading the idling current has to go up.
Regarding to the MOSFETs, I do not see any graphs for the NE so you can compare the difference in details to the NF, in the idling mode we do not know what the Rds is to calculate the power dissipation at 90mA of current.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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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 -
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... -
Hey guys,
i have a asus motherboard here and as the title says after the first mosfet (in the picture) there is nothing more than 3.15v.
I injected 19v and max. 1 amp at the charging port and there is not voltage drop or smth. It's just taking 19v and 1 milliamp.
Then i tried to inject 19v and max 1amp after the current sensor and there it first takes 19v and 4 milliamps and after 2 seconds it is taking nothing (no current).
I measured on the coils on board everything seems fine. Also the main power rail is not shorted (infinite resistance).
Now i thought something... -
The board number is GU502DU. I repaired this a couple weeks ago and it came back with the same issue, same mosfet failed (PQH9201). I'm hoping that the GPU was spared this time.
I used the same replacement part (purchased from Mouser) and I'm certain the soldering was done properly since it took just as much effort to remove as before. What could cause this same mosfet to fail? I'm thinking if it was unsuitable then the others would fail too. I looked for similar failures on YTube and the mosfet was replaced with AOE6930 in one instance and AOE6932 in the other but it's possible that the... -
I have an Asus GA502D, it had a blown mosfet which I replaced and the laptop booted into windows, a few mins later it shut off, the same mosfet was blown. I thought maybe just a bad mosfet but same thing happened again, a few mins in windows and shuts off.
I have removed the mosfet and can run the laptop no problem
The MOSFET is FDPC5018SG
Can anyone point me in the direction of what could be the cause of this, could it be the controller rt3663bc?
Thanks
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