Repair Of A Toshiba Windows 10 Laptop
On a cloudy and rather cold snowy day this 27th of February my shop owner friend Chafik phoned me if I liked to help him in fixing a couple of dead laptops if I had time. And since I’m always happy if I can participate in increasing his success rate, I visited him like I often do since we met about 8 years ago. Which for me also is a good way to keep my knowledge on new repairs and new devices fresh.
And it is always nice to talk about electronics while having a short rest and a coffee. One dead laptop today had very tiny unknown ic’s and mosfets we couldn’t replace because we had none of them and neither had we a helping matching schematic. Which is very much needed in such cases were these special tiny smd components make it hard to determine their function. So we put that one aside and looked at another Toshiba laptop that also was completely dead.
Previous photo showed the mainboard top view of this Toshiba C50-A-19U laptop. Below on the right we see the 19V power input jack that functioned fine but the voltage never switched on after the push button on the front was pressed. After we examined the bottom solder side of the mainboard we noticed the 2 mosfets that normally switch through the input voltage. Below on the right next to the left of the Q component.
Above photo showed the solder board side after one of both mosfets that shorted (the empty spot on the left right next to the 2R2) was removed. But when we replaced the original IOR P323S mosfet by another n-channel mosfet we tested the laptop but it still was not working. And with our DMM we measured about 450 ohm over both mosfets. That implied that also the second original IOR P323S mosfet could be defect. Finding a datasheet for these IOR P323S mosfets failed but the bottom marking on top of the defect mosfets showed marking F8707x which is a n-channel type of mosfet. So to be sure if that would fix the laptop we replaced both mosfets by 4800B n-channel mosfets we had at stock and re-tested the Toshiba laptop. It immediately started to work. If they will hold we do not know yet but it seems to have done the trick.
Normally Aliexpress or other firms show components if we look for them but IOR P323S mosfets were never shown like its datasheet we couldn’t find either. A datasheet of the F8707 was easily found but we still do not know if that is the mosfet we were looking for and needed here.
Previous photo on the left the defect IOR P323 mosfet, and photo on the right our new 4800B mosfet.
On the left again our defect IOR P323S mosfet.
Keep in mind that the 4800 mosfet is in a single and a dual mosfet package available depending on if it is a Single Si4800BDY mosfet from Vishay or a Dual one with marking AO4800B from Alpha&Omega.
Below the extract from the Vishay single Si4800 9A 30V mosfet datasheet:
——————————————————————————————-
Below an extract from the datasheet of the AO4800 6.9A 30V Alpha & Omega dual mosfet:
Next the extract of the datasheet of the presumed F8707 n-channel mosfet:
After both mosfets were replaced the Toshiba laptop worked again like next photo proves.
After the laptop was fixed we only needed to replace the Lithium 3V battery and adjust the time and date to make sure that everything kept working as expected. Because if time and date are out of sync it will likely be impossible to open any browser and go online which is a safety measure that normally prevents such actions. And after a decent burn-in program test my friend will phone the customer that his now Windows 10 laptop is fully functioning and ready to be used again!
Looking at adverts of the sellers who sell the F8707 mosfets on Aliexpress confirmed that the IOR P323 marking on top of the now replaced mosfets is not the actual mosfet type marking because the number after the IOR Pxxx never was the same and likely was just a production stamp marking on the actual n-channel IRF 8707 mosfet.
As can be found on page 8 of the IOR’s IRF8707 datasheet below:
Albert van Bemmelen, Weert, The Netherlands.
Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
P.S- If you enjoyed reading this, click here to subscribe to my blog (free subscription). That way, you’ll never miss a post. You can also forward this website link to your friends and colleagues-thanks!
Note: You can read his previous repair article in the below link:
https://jestineyong.com/secret-of-recovering-data-from-defect-usb-sticks/
(84)Dislikes
(0)
11 Comments
Leave a Reply
Patrick Ribbsaeter
March 5, 2020 at 8:52 pm
Nice explanation. Thank you
Parasuraman S
March 5, 2020 at 9:01 pm
Information, data-packed article with detailed notes! A laborious task for the sake of others! Hat's off to you, dear!
Waleed Rishmawi
March 8, 2020 at 3:24 pm
Very impressive work my friend and thanks for sharing. Have a blessed day
Francisco Rica
March 9, 2020 at 7:35 am
dear Alert:
Excelente reparation. Could you explain how test both MOSFET? When you said:
"And with our DMM we measured about 450 ohm over both mosfets. "
What pins do you measured? Do you measure the MOSFET out of PCB?
Thanks
Albert van Bemmelen
March 10, 2020 at 4:06 pm
Testing Mosfets is easy but at best can be only done off board. On board we only can measure if they are short circuiting or having a wrong resistance which tells us that they must be defect. By using your DMM in diode test you can switch any of the in the article used mosfets in on state or deactivate them to open switches. Gate is mostly pin 4 (in a single Mosfet). pin 1 to 3 are Source and 5 to 8 are the Drain pins. And if you place your Multimeter red and black input probes on pins 4 and any of the source pins you can change the condition the Mosfet is in by switching the black and red DMM probes. If it conducts (is activated) source and drain are connected. And if the mosfet always conducts or is short circuiting between Gate and Source or never acts as a 'digital' switch, you know it is a bad one and must be replaced.
Robert Calk Jr.
March 9, 2020 at 12:24 pm
Good job, Albert! I am glad that you were able to make the laptop happy again.
Saqib Sami
March 10, 2020 at 4:29 am
Good work.
Humberto
March 12, 2020 at 4:18 am
Hi Albert. Good repair. Congratulations.
Ennytee
March 13, 2020 at 12:36 am
Well done Albert. This is an info packed article. I really enjoyed the read.
Andrea Del Corso
March 13, 2020 at 11:23 pm
Well done Albert,compliment for the interesting article!
aziizi
July 21, 2020 at 2:01 pm
hello
am an avid reader of your articles.this is great micro soldering.Apart from Alibaba,where else can we source for micro components,spares and tools and what are common universal smd components to stock.thanks