Problem identifying a resistor value

Other Hardware General Electronics
1

I have problem identifying a resistor on Arduino Mega 2560 R3 (i have marked it with a red ring on the picture), i think it's R14 10k ohm on the schematic but not really shure, need to know in order to replace it.

And another question, there is a part next to the usb port that is gold and black and marked 501L on the picture (but my board is marked X505), i think it's a resettable fuse, anyone that can correct me?
To reset it i gues i remove it and resolder it with the opposide polarity?

Sorry for my bad english but it's not my native language.

Arduino-Mega-2560-Pinout2.jpg
Arduino-Mega-2560-Pinout2.jpg2785×1353 938 KB

2

I only see a ceramic decoupling capacitor there. Ceramic caps are brown, resistors are usually black with
white printing.

The cap looks to be on the input of the 5V regulator.

R3 is a quad resistor array anyway.

3

Refering to the schematics, it appears to be C2

And another question, there is a part next to the usb port that is gold and black and marked 501L on the picture (but my board is marked X505), i think it's a resettable fuse, anyone that can correct me?

Yes, its a resettable fuse, part# MF-MSMF050-2

4

bljardkungen:
To reset it i gues i remove it and resolder it with the opposide polarity?

No, it's a self resetting fuse. Just remove the load, and it will reset.

5

bljardkungen:
And another question, there is a part next to the usb port that is gold and black and marked 501L on the picture (but my board is marked X505), i think it's a resettable fuse, anyone that can correct me?
To reset it i gues i remove it and resolder it with the opposide polarity?

It is what's called a positive temperature coefficient (PTC) resistor. It starts out with a very low resistance, but when current goes through it it heats up based on the formula P = I2R. This heat causes the resistance to rise. Below a certain level, the heat is mild enough to not cause a large change in resistance. However, once the current goes above a certain threshold, the resistance rises out of control and severely limits the current flowing through the "fuse".

To reset the fuse, you just need to remove power and wait a few seconds for it to cool off and return to its normal (low) resistance.

6

Jiggy-Ninja:
It is what's called a positive temperature coefficient (PTC) resistor. It starts out with a very low resistance, but when current goes through it it heats up based on the formula P = I2R. This heat causes the resistance to rise. Below a certain level, the heat is mild enough to not cause a large change in resistance. However, once the current goes above a certain threshold, the resistance rises out of control and severely limits the current flowing through the "fuse".

To reset the fuse, you just need to remove power and wait a few seconds for it to cool off and return to its normal (low) resistance.

Thanks for your detailed response, didn't even know fuses/resistors like that existed, really cool.

7

dlloyd:
Refering to the schematics, it appears to be C2


Yes, its a resettable fuse, part# MF-MSMF050-2

That part is not on the schematic i found, i might have found the wrong one.
Do you have a link to the full one?

8

bljardkungen:
That part is not on the schematic i found, i might have found the wrong one.
Do you have a link to the full one?

Click "schematics" in the post you quoted - he linked to the full schematic he pulled that from.

9

DrAzzy:
Click "schematics" in the post you quoted - he linked to the full schematic he pulled that from.

Missed that, thank you for your fast reply and thanks to you all for your kind and fast help :slight_smile:

10

It is F1 in the schematic next to the USB connector.

11

Jiggy-Ninja:
To reset the fuse, you just need to remove power and wait a few seconds for it to cool off and return to its normal (low) resistance.

Probably minutes - polymer melting/recrystalization is not a sharp phase change.