# 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.

Can you suggest me a similar capacitor I can buy?
I am not able to understand what's written on the other capacitor.
Thanks

#### MrChips

Joined Oct 2, 2009
22,502
If the supply voltage is 3.3V I would guess 100μF 6.3V tantalum electrolytic capacitor.

Thread Starter

#### Albojk

Joined Oct 24, 2020
2
Thank you, that was the information I was looking for

#### MisterBill2

Joined Jan 23, 2018
7,693
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
22,502
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
7,693
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
22,502
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==

#### mrnottingham

Joined Nov 6, 2020
1
oh, good information I want this information last many days.