Sorry for the mcpcb soldering gore…I know I’ve screwed up!
But any chance I can save this LT1 mcpcb?
I’ve sanded down the copper pad on the bottom right too much (yes with a dremel) trying to get some surface that solder would stick to. In an attempt to wire up a new driver (charging port blew up on original).
Can I not bother with the black wire im trying to solder and just leave the LEDWW one connected?
Thanks!
What you wanted to use instead was some flux. These pads are thinner than a hair, now it’s gone.
Yes, half of the LEDs will stay dark.
You could create a new pad by removing the solder mask at the right location.
Thanks Sammy.
How would i work out the right location do you know pls?
I just did a quick wiring up and put batteries in and figured out the WW prbly stands for Warn White? As the 2700k LEDs are not coming on in my test.
Or is it not worthwhile trying any more and just join up the wires that are left and live with 5000k only?
Once you get the wire reconnected to a new spot, before you connect the driver to power, ensure the damaged pad has not shorted to the base layer of the MCPCB.
Thank you James!
Sorry but how do i check that exactly? I do have a DMM. Just not sure how to use it for this scenario.
So you’ll scrape off some of the solder mask for a new location for that wire. Solder the wire on, then use the DMM to check for continuity between the new wire (solder blob is fine) and the underside of the board. There should be no continuity.
If there is continuity, then the conductive layer from the damaged pad is touching the core of the board and needs to be fixed.
There’s some glare in your pic and it’s hard to make out the traces. Perhaps a couple other pics from different angles and with indirect lighting would help us suggest a new wire spot.
Ok i think i understand.
Heres a couple more pics. If you could point me in the right direction for a new pad thatd be amazing. Meanwhile i will go research how to check continuity with a DMM!
I’m having a hard time figuring out the trace paths. I can’t focus on it right now, but it looks like perhaps those lines are separating the current paths, not the paths themselves. From what I can tell, it looks like the LEDs and labels are actually reversed from what the labeled black wires show, i.e. the missing wire would be the neg for the warm white (WW) not neutral white.
Anyone else see that? Sorry, on my phone and distracted.
All good mate i really appreciate you having a look for me. Whenever you can and let me know if i can take another pic from a different angle or anything.
I’ll try to look closer in a couple hours. Does your DMM have a diode check mode?
Yes it does. Juat reading the instructions now. Its an Excel XL830L model. And
Edit: I checked continuity from the damaged pad and the back of the board and no sound…so all good there I think. definitely has diode check mode.
Try diode check on the good wires, DMM red to board red, black to black. If that works as expected (lights up LEDs) then try DMM red to red wire, black to damaged pad. Move it around on the pad to try to get it to light up.
Excellent i had no idea about that. Ive already learnt something (2 things actually) thank you so much.
So the 5000k leds light up no problem with red and black wires connected as they are.
The 2700k leds also do light up in a couple of small spots in the damaged pad area (on the outside edges of the damaged pad pitted area) and also if you maybe noticed i tried scraping away a very small area on one of the tracks near the black wire LEDWW pad and that also lights up the 2700k leds…although its a bit spotty so obviously not a good connection (i stopped scraping it as i didnt know hat i was doing).
What would you suggest for next steps?
So the labels on the board are wrong, as I thought. The faint lines are not traces, but instead separate the traces. You can carefully scratch away the white mask anywhere near the damaged pad to expose new copper. You have a pretty large are to work with inside that circle near the pad. Maybe use a knife. Just go slow. Get a nice new area exposed and use flux when soldering.
Then check the new solder joint for continuity with the bottom of the board. By checking the new joint you will effectively also check the damaged pad.
@James_C you are my hero thanks so much for your time and attention!
All fixed. I carefully scraped away a new copper area and after several frustrating attempts with much flux and other f words i managed to get the black wire attached.
All this stemmed from me blowing up the USB charging controller whilst away camping (by plugging the LT1 into my 12v system in the car and smoke coming out of it), ordered a new driver from sofirn and finally, with your help, got it connected up again.
Bit messy with thermal paste everywhere and rough soldering elsewhere to get the other wires from the controller connected…but its done and its working!
And it isnt on fire or exploded or electocuting me. So im happy.
Thanks again mate. Really very kind of you to help me out. I hope this post helps someone in future and I’ll also pass on the kind gesture one day of helping someone out i hope.
I’m glad you got it working! I’m happy to help. There are many other helpful people here, too. I learned most of what I know from posts here. It’s a great resource.
BTW, your soldering struggles might be due to your iron not getting hot enough (although a board that big is always going to wick heat away). When I upgraded my iron (from a $10 model to just a $30 one) it made a huge difference. There are lots of threads on irons. Just something to think about if you plan to do modding.
