I accidently destroyed a surface mount component from my DE10-Nano pcb

If you have just joined the community and are seeking help then post/ask here.
xav2075
Posts: 1
Joined: Mon Jun 29, 2020 1:57 pm

I accidently destroyed a surface mount component from my DE10-Nano pcb

Unread post by xav2075 »

Because I was clumsy in fitting my DE10-Nano into a case I 3D printed I destroyed a surface mount device from the underside of the circuit board. After I did that the USB OTG port stopped working. So the board could boot into MiSTer but no keyboard or joypad would work with it.

I do some hobby electronics but I have no hands on experience with SMD components. From doing a google the type of device I destroyed is a capacitor because the middle of the package is coloured brown. Could someone tell me what the value of the capacitor in farads?

The SMD component i destroyed is highlighted by a yellow arrow at the top left of the image.

Image

FPGAzumSpass
Posts: 21
Joined: Sat May 23, 2020 12:55 pm

Re: I accidently destroyed a surface mount component from my DE10-Nano pcb

Unread post by FPGAzumSpass »

According to schematics
(found here: https://www.terasic.com.tw/cgi-bin/page ... 6&PartNo=4)
It is C85.

That's a 0,1u, 16V capacitor used for USB Voltage.
c85.png
I would expect the USB to still function, unless you have a short there or damaged the other Cs, too.
But better wait for the expert opinions on that guess.
You do not have the required permissions to view the files attached to this post.

User avatar
Hodor
Posts: 12
Joined: Mon May 25, 2020 8:29 am

Re: I accidently destroyed a surface mount component from my DE10-Nano pcb

Unread post by Hodor »

Soldering such a tiny SMD component is not an easy matter I´m afraid. I wish you luck with the job though maybe someone more experienced near you can help.

User avatar
Grabulosaure
Posts: 30
Joined: Sun May 24, 2020 7:41 pm
Location: Mesozoic
Contact:

Re: I accidently destroyed a surface mount component from my DE10-Nano pcb

Unread post by Grabulosaure »

I would suggest to do nothing, unless the damaged capacitor is in short-circuit.
These are decoupling capacitors, they are in parallel to reduce noise.

xav2075
Posts: 1
Joined: Mon Jun 29, 2020 1:57 pm

Re: I accidently destroyed a surface mount component from my DE10-Nano pcb

Unread post by xav2075 »

I desoldered the remains of the destroyed capacitor using a USB microscope. So I think I could be ok soldering in a replacement.

One the replies mentioned it might be a capacitor in parallel to reduce noise. I had a similar thought and wondered is this really the cause of why the USB otg port is no longer working. I had a look for other missing components but I could not find anything missing looking through the USB microscope.

The USB serial port is recognized when plugged into my Windows 10 PC. I can get a serial console to read the debug output of the board. But it seems I can't use the console to write output to the board. Like logging in as root to get a command line.

xav2075
Posts: 1
Joined: Mon Jun 29, 2020 1:57 pm

Re: I accidently destroyed a surface mount component from my DE10-Nano pcb

Unread post by xav2075 »

I dont think the USB micro connector is faulty because I tested for 5V at the connector solder points near 'HPS USB OTG' text on the board. And there was no 5V present. There is 5V elsewhere on the board including on the GPIO connectors.

And I have tried using a powered USB hub to try and get keyboard and joypad working but that did not work.

xav2075
Posts: 1
Joined: Mon Jun 29, 2020 1:57 pm

Re: I accidently destroyed a surface mount component from my DE10-Nano pcb

Unread post by xav2075 »

I got a working serial terminal to the board running Mister. dmesg log had 3 particulary interesting messages:

[ 0.093581] sopc@0:usbphy@0 supply vcc not found, using dummy regulator
[ 0.897276] ffb40000.usb supply vusb_d not found, using dummy regulator
[ 0.903912] ffb40000.usb supply vusb_a not found, using dummy regulator

With a datasheet I checked the 7 power pins on the USB3300 ic and they all had the right voltages when the board was powered

My DE10-Nano board differs from the offical schematic in that U7 is not a TPS2553DRVR IC but instead is a 5 pin smd device labelled 'U3D HG'.

On the electronics side I am definitely a novice and poking around in the dark with this problem.

Post Reply