Bernie.H
Posts: 13
Joined: Wed Oct 03, 2012 3:16 pm

C17 pad destroyed

Wed Oct 03, 2012 3:22 pm

Help,
clumsy soldering led to the destruction of the lower pad when soldering C17. Please advise on how to go about rectifying my error. I have sourced new capacitors, but suspect that I will need 'through hole' ones, not smd. The schematics show that c17 is connected to ground, but which pad connects to ground.
Please advise.
Many thanks,

Bernie H

User avatar
Tandy
Posts: 39
Joined: Wed Jun 13, 2012 5:27 pm
Location: Oxford
Contact: Website

Re: C17 pad destroyed

Wed Oct 03, 2012 3:53 pm

C17 is a decoupling capacitor (just there to stablise the Vcc power to the microcontroler), fortunatley there is also another one near by C15 that may be sufficient. Failing that the bottom pad of C17 is the ground and the top +3.3V, Perhaps the easiest way to repair it is to put a new SMT capacitor on the underside of the board on pins 21 & 22 of the ATMEGA socket. I suggest removing the microcontroller from the socket before attempting to solder it.
Tandy - The home of electronics - www.tandyonline.co.uk

Bernie.H
Posts: 13
Joined: Wed Oct 03, 2012 3:16 pm

Re: C17 pad destroyed

Wed Oct 03, 2012 4:52 pm

Goodness, many thanks for the fast reply. I will solder the pins when my new capacitors arrive. Again, many thanks for the reply.

Bern

User avatar
pmj1979
Posts: 17
Joined: Tue Sep 04, 2012 12:06 pm

Re: C17 pad destroyed

Thu Oct 18, 2012 5:21 pm

Bernie, Did you get your board sorted?
I just did the same thing on the top pad of c17. Not exactly sure what to connect to what now.

I need to find the schematic and work out where the top pad connects next... it looks like the top of R24 only but not sure.

Tandy, If the top pad of C17 does only connect to the top of R24 can I just run a wire between the two or might this mess with other things?
Pi from Element14 (still not got the first Pi from RS :( )
Rev2 board | Belkin 7Port powered hub | ASUS N10 WiFi | Logitech Wired Mouse | Behavior Tech Wired KB

Bernie.H
Posts: 13
Joined: Wed Oct 03, 2012 3:16 pm

Re: C17 pad destroyed

Thu Oct 18, 2012 6:26 pm

Hi pmj,
My commiserations. Short answer is no. When I finished my board, I checked all OK, and then applied jumper 7 for power. Somewhere there is a short as nothing worked, and the regulator was glowing (not really), but extremely hot. I was advised to solder capacitor between pins 21 & 22, which I did, but since removed. Looking at the schematics I think it should go between 20 & 21, but have not proceeded as yet. I have taken delivery of a new kit, which I will build over the coming weekend, and hopefully, all will go well. If so, I will donate the old board to some one who is willing to try and trae the fault. Good kuck,

Bern

User avatar
pmj1979
Posts: 17
Joined: Tue Sep 04, 2012 12:06 pm

Re: C17 pad destroyed

Thu Oct 18, 2012 6:51 pm

After I peeled the pad off I removed the capacitor as best I could, It hadnt come of compleatly so i was trying to find out what the next connection would have been to simply jump a wire from thr cap to the next hop.

on here...
http://img716.imageshack.us/img716/483/pcbavrpict.gif
it looks like mine only connects to the top of R24 next door. Ive re-soldered the cap back on and will cross my fingers and hope that its all ok. if not ill look at attaching a wire between the two.

Looking on the same diagram, if you only lost the bottom pad, it goes straight to ground because that contact also runs left (not shown on the diagram) and connects to the ground?!
http://raspi.tv/wp-content/uploads/2012 ... tBoard.jpg
Doesnt help the ground issue though if it is more than C17.

Good luck with the 2nd one! :)
Pi from Element14 (still not got the first Pi from RS :( )
Rev2 board | Belkin 7Port powered hub | ASUS N10 WiFi | Logitech Wired Mouse | Behavior Tech Wired KB

Return to “HATs and other add-ons”