Advice: Solder pad torn off Apple logic board - Page 1
Forum section: electronics / projects

author: michaelp
author_rank: Contributor
timestamp: December 21, 2013, 05:25:57 am
content: Electronics novice here, been watching a few of Dave's videos and wanting tackle a Mac repair myself that has a torn off connector.As you can see from the image below, I've lost pins 31 and 32 (far left) and pins 1, 2, 3 and 4 (far right). Pins 1 and 2 have had their solder pads completed torn off.According to the schematic, pin 1 and 32 are ground. So I figure I can solder in a new connector, and run a wire from Pin 1's connector to another ground somewhere else.However what am I going to have to do with Pin 2? From what I understand, it's not easy to repair the solder pad as it's a multi-layer PCB. So does that mean I need to find where R9050 and run a wire from the new connector to R9050?Thanks for the advice!

author: Psi
author_rank: Super Contributor
timestamp: December 21, 2013, 05:46:40 am
content: - Source and buy a new connector- Unsolder and remove the remains of the damaged connector.- Scrape then tin the two vias (near the missing pads) with the iron (so you can easy solder to them later).- Use some solder wick to clean off all the good pads- Apply a tiny bit of solder paste and reflow/solder the connector back onto the good pads- Bend some thin tinned wire so can sit, or be held, on the pcb linking the connector pin and it's corresponding via from step 3.- Solder this wire to both the via and connector pin. With everything clean and tinned you should just need to touch the iron too it and it will join. (repeat last two steps for the other broken pad)- Carefully cut the excess wire off as close as possible without putting any pressure on the join. Then fold any excess wire over so it cant short to anything.Note: It's important to cut the wire as the final step because it's almost impossible to hold a pre-cut 3mm piece wire in position. Much easier to hold a 50mm wire in position then solder and cut down to 3mm after. Sometimes it's easier to temporarily solder the other end of the 50mm wire to some random nearby location on the PCB. That way it will stay there and you can bend the wire in which ever way you need until its sitting in the right place before touching it with the iron. Then you can remove/cut this anchore point later

author: michaelp
author_rank: Contributor
timestamp: December 21, 2013, 06:03:19 am
content: Thanks Psi. New connector is already on it's way. Do you recommend I remove ALL the original pins and solder the entire new connector?The connector on it's way is a 1:1 identical part. I was just going to remove the unneeded pins, and only solder the 5 missing pins on the new connector.

author: Rerouter
author_rank: Super Contributor
timestamp: December 21, 2013, 07:33:22 am
content: another suggestion is to track down the resistor that pin 2 passes through, even on multilayer boards its rare to mound passives inside the board

author: Psi
author_rank: Super Contributor
timestamp: December 21, 2013, 08:19:58 am
content: Quote from: michaelp on December 21, 2013, 06:03:19 amI do recommend you replace the entire connector yes.Trying to pull out the unneeded pins from the new connector and then push the existing ones through will damage something.

author: michaelp
author_rank: Contributor
timestamp: December 21, 2013, 08:22:08 am
content: Given that the vias are fairly accessible, what would be the advantage of finding the resistor?My guess is that working with 2 torn off pads could be quite fiddly, especially since I am a novice. So would the advantage being that they'll be less chance for me to bugger things up if I try to run a wire between the 2 points.Quote from: Rerouter on December 21, 2013, 07:33:22 am

author: michaelp
author_rank: Contributor
timestamp: December 21, 2013, 08:22:58 am
content: That makes sense. Thanks for the advice!Quote from: Psi on December 21, 2013, 08:19:58 am

author: dave_k
author_rank: Frequent Contributor
timestamp: December 21, 2013, 09:46:03 am
content: NOSTUFF on the schematic means the part is not mounted, right? If so PIN 2 is not connected to anything..

author: Psi
author_rank: Super Contributor
timestamp: December 21, 2013, 11:22:27 am
content: No idea what that NOSTUFF text means.I guess it could be a bad translation of "not populated" which is what you'd expect to see if a component was left off the pcb.hm.. Actually, i know what that is. It's a text field in their schematic design software which has no text defined. So it means nothing. Pin 2 is definitely used.

author: amyk
author_rank: Super Contributor
timestamp: December 21, 2013, 12:10:34 pm
content: NOSTUFF means the component is not fitted.And... silkscreen on a Mac PCB? How old is it?

author: Psi
author_rank: Super Contributor
timestamp: December 21, 2013, 12:25:35 pm
content: really? seems a bit informal to be a real thing.

author: TheBay
author_rank: Unknown
timestamp: December 21, 2013, 09:22:08 pm
content: Get a new connector and some Kynar

author: michaelp
author_rank: Contributor
timestamp: December 22, 2013, 03:07:41 am
content: So Pin 2 isn't even really important? Do I even need to bother trying to fix/connect the pad?And this is a 2010 iMac.

author: Psi
author_rank: Super Contributor
timestamp: December 22, 2013, 03:12:48 am
content: Quote from: michaelp on December 22, 2013, 03:07:41 amIf R9050 is missing then SMB_DP_TCON_SCL doesn't connect to the connector, however I2C_TCON_SCL may connect to other circuits on other pages.

author: amyk
author_rank: Super Contributor
timestamp: December 22, 2013, 01:02:42 pm
content: I2C_TCON_SCL:I2C: You should all know what this meansTCON: Timing controller (in a display)SCL: Serial ClockSo it's the I2C bus for the LCD driver, except they probably decided it wasn't needed/implemented.