Understand capacitor value

Thread Starter

Albojk

Joined Oct 24, 2020
2
Hi all, recently I accidentally broke my pc keyboard with a usb hub overvolted.
I found a burnt capacitor and I would like to change it before buying a new keyboard.
I think its the same as another on the same board.
IMG_20201024_224321.jpg
Can you suggest me a similar capacitor I can buy?
I am not able to understand what's written on the other capacitor.
Thanks
 

MisterBill2

Joined Jan 23, 2018
7,234
Actually, the capacitance is given by the 107. Since 106 = 0.1 mfd, 107 will mean one microfarad, and in a keyboard you do not see more than 5 volts. And since it is a chip capacitor that is a reasonable value for that size.
Unfortunately, if the over voltage was enough to damage the capacitor, probably other things were also damaged.
 

MrChips

Joined Oct 2, 2009
22,067
Actually, the capacitance is given by the 107. Since 106 = 0.1 mfd, 107 will mean one microfarad, and in a keyboard you do not see more than 5 volts. And since it is a chip capacitor that is a reasonable value for that size.
Unfortunately, if the over voltage was enough to damage the capacitor, probably other things were also damaged.
104 = 100000pF (i.e. 10 and four zeros) = 0.1μF

105 means 10 x 10^5 = 1μF
106 = 10μF
107 = 100μF

Similarly, a 103 resistor = 10kΩ
 

MisterBill2

Joined Jan 23, 2018
7,234
This is known as an "OOPS!!" You are right, it is the 104 that is the 0.1 mfd. It has been a long day for me today, that is my excuse. Also, I should have noticed the polarity mark on the case. That should have been my other clue.
Is it reasonable for a chip capacitor to have that much capacitance in that small a package?
You could unsolder it and see what happens, and see if it has shorted. And still there may be another part that has failed also.
 

MrChips

Joined Oct 2, 2009
22,067
This is known as an "OOPS!!" You are right, it is the 104 that is the 0.1 mfd. It has been a long day for me today, that is my excuse. Also, I should have noticed the polarity mark on the case. That should have been my other clue.
Is it reasonable for a chip capacitor to have that much capacitance in that small a package?
Surprisingly, yes!
You can get 100μF 6.3V ceramic chip capacitors in 0805 package and tantalum in a wider selection of size/capacitance/voltage.

https://www.mouser.com/ProductDetai...RM21BR60J107ME15K?qs=Ey7/XF42M3ey7cnxiIYXug==
 
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