On Friday, December 7, 2018 at 6:56:20 PM UTC-8, Jeff Liebermann wrote:
On Mon, 3 Dec 2018 20:53:52 -0500, bitrex wrote:
Due to an unfortuante jab with the head of a screwdriver it looks like I
have at least one, possibly two broken traces on this GPU card, on the
traces running between the processor and VRAM. Result is corrupted
display output/won't switch into high-resolution modes. The ram is BGA
and the GPU likewise and
Common problem with motherboards and steel computer cases with sharp
edges.
under a small heat-sink so hard to test
continuity, plus the trace width is very small, looks like perhaps 4 mil:
Ummm... 4mil (0.004in) is roughly #38 AWG solid wire.
https://www.calmont.com/wp-content/uploads/calmont-eng-wire-gauge.pdf
Looking further down the chart, you should be able to find stranded
wire using something in 2 or 3 mil range.
https://www.dropbox.com/s/ig9h3vjze5omlie/2018-12-3%2018-11-20.jpg?dl=0
Nicely gouged.
Any suggestions for mending a break on a trace like this?
Yep. Dave Platt has the right idea. I'll add a few details.
Find some thin plated wire and tin it. Sometimes, I get fancy and
flatten the round wire but that's not really necessary. Carefully
scrape of the solder mask from over the PCB traces and tin those.
Liquid flux helps. Solder one end of the wire, lay the remaining wire
across the gap, solder the other end, and CAREFULLY cut off the excess
wire. Don't use a knife as you're likely to also cut the PCB trace.
Clean off the flux with alcohol, let dry, and test with an ohmmeter.
Then, test the PCB. If everything looks good, cover with a little
Krylon or other acrylic paint. If you're not sure about the fix, then
use some wax, which is easily removable.
As Ralph Mowery mentioned, a microscope is very helpful. I use this
in the office:
http://www.learnbydestroying.com/jeffl/pics/microscopes/Olympus%20SZ30/slides/SZ30-01.html
and this at home:
http://www.learnbydestroying.com/jeffl/pics/microscopes/Bausch%20and%20Lomb/index.html
I have 6 microscopes, not including parts scopes. Only 3 are suitable
for soldering and PCB inspection. I also have a CMOS camera that fits
in place of one eyepiece and which can be used for photos and display
on an LCD monitor.
Notice the use of a microscope, flux, and tinning. However, I
disagree with the use of an Xacto knife to cut the wire.
QUICK CIRCUIT TRACE REPAIR
https://www.youtube.com/watch?v=a5A61fIu0kk
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I forgot about the microscope aspect. I'm crosseyed and never learned to see in 3D so stereo scopes have no special value to me. They got me one of these at work.
https://www.amazon.com/Opti-Tekscope...5OLQ6 7NVPFZA
I liked it enough that I bought one for home. Looking into the UV window of a 256K EPROM I found the Fujitsu name on the silicon and found that good enough for me. Got mine on eBay several years ago for $45 out the door. Hard to beat that value.
G²