Help troubleshooting a surface mount LED?
- Thread starter AnubisGuard
- Start date
I do electronics professionally (for 20+ years) and I hate 0402s, they're meant for machine placement!!! Doing them by hand sucks. I did find a 0603 fits on 0402 pads alright for a kluge. Officially it does not meet IPC specifications, but I only work on prototypes!
xl97
Master Member
Update:
arrived (just now)
un-plugged 'usb' cable.. it booted up (must also act as a cut-off, like we used to do in the saber scene)..
*(still not clear how the li-po gets re-charged when plugged into USB port though?.. anyways.. not the issue)
I -can not- duplicate the issue..
I let it run..
I moved it around.. on side(s)... up-side-down...etc.. the GREEN LED (LD3) has -not- missed a beat.
Update 2: I take that back.. I CAN in fact duplicate it.... I was genetly putting pressure on the board (with my fingers).. as if it was in a case.. or slightly 'bent'... and in certain 'areas of pressure'.. the green led does in not light up in the sequence.
I'm gonna dab the solder joints real quick to ensure there is no cold joints anywhere..
arrived (just now)
un-plugged 'usb' cable.. it booted up (must also act as a cut-off, like we used to do in the saber scene)..
*(still not clear how the li-po gets re-charged when plugged into USB port though?.. anyways.. not the issue)
I -can not- duplicate the issue..
I let it run..
I moved it around.. on side(s)... up-side-down...etc.. the GREEN LED (LD3) has -not- missed a beat.
Update 2: I take that back.. I CAN in fact duplicate it.... I was genetly putting pressure on the board (with my fingers).. as if it was in a case.. or slightly 'bent'... and in certain 'areas of pressure'.. the green led does in not light up in the sequence.
I'm gonna dab the solder joints real quick to ensure there is no cold joints anywhere..
xl97
Master Member
Here is a video of it during the 'breaking' process..
To me it seems like it probably a lifted bad or trace.. and when flat, still makes sufficient contact... however when the PCB has pressure applied to it and it bends/arc in certain areas.. it seems like it may be lifting the pad/trace.. and breaking connection.
gmprops
If there is anything else you suggest trouble shooting, please let me know.
Thanks
To me it seems like it probably a lifted bad or trace.. and when flat, still makes sufficient contact... however when the PCB has pressure applied to it and it bends/arc in certain areas.. it seems like it may be lifting the pad/trace.. and breaking connection.
gmprops
If there is anything else you suggest trouble shooting, please let me know.
Thanks
AnubisGuard
Master Member
That explains why it tends to break once installed – I'm using a real Oregon Scientific Nightfinder clock for the body, which has slightly tighter tolerances and a concurrently smaller interior than the Stapleton body kit meant for use with this board. It's a bit a of a squeeze to get it in there.
Yes, it looks like it is a raised or broken trace. They can be tricky to find but not impossible. I would still be happy to fix it if you want to send it to me.
You don't need to find the broken trace. You can run a wire from the output to the resistor that bypasses the trace. It won't do any harm while the trace is working.
Who soldered this board? I have to be honest it's a right mess... T3 or 4 looks like one of the pins don't have good contact with the board. Looks like the transistor that feeds that led. I can't view the pic while typing on phone........ Also one of those rgb leds look like the pins are bridging.
As for 0402s I've got some masochistic joy to look forward to. My voy tricorder v2 boards are in, and I'll be soldering a couple up soon. And they use loads of 0402s as the board is so densely populated. I'll make a proper post when I have something cool to show.
If the trace is broken try and find the crack, scrape off some solder mask where the crack is and with some good leaded solder solder a small blob bridging the crack.
But take another look at that 3 pinned transistor. That might be the issue.
As for 0402s I've got some masochistic joy to look forward to. My voy tricorder v2 boards are in, and I'll be soldering a couple up soon. And they use loads of 0402s as the board is so densely populated. I'll make a proper post when I have something cool to show.
If the trace is broken try and find the crack, scrape off some solder mask where the crack is and with some good leaded solder solder a small blob bridging the crack.
But take another look at that 3 pinned transistor. That might be the issue.
oh strange now im on desktop theres a whole lot more thread showing... see you trouble shooted a lot
right RGB1 looks like it has a solder bridge on the top left pins. T4 looks like one of the pins arent soldered to the pad.
T4 looks like it feeds LED3 via r44, so that solder joint might be the issue.
right RGB1 looks like it has a solder bridge on the top left pins. T4 looks like one of the pins arent soldered to the pad.
T4 looks like it feeds LED3 via r44, so that solder joint might be the issue.
xl97
Master Member
Thanks MangyDog..
I'll take a closer look at the transistor tonight when I get some time!
I hope you are planning to make a solder paste mask/stencil for those 0402's LOL
I now use my vinyl cutter (not even my laser cutter) to cut a solder paste stencil out of some overhead projector transparency..
I smear my paste on.. remove stencil.. populate board... and I re-flow/bake in my a $17 toaster oven from Wal_mart!
There is a tool-chain out there to send GERBER files directly to my vinyl cutter (WAAAAAY better than trying to use the .dxf options you see out there)
I have some write-ups/tutorials on it somewhere.. LOL (Arduino forums..... dangerous protypes forums for source..etc)
I'll take a closer look at the transistor tonight when I get some time!
I hope you are planning to make a solder paste mask/stencil for those 0402's LOL
I now use my vinyl cutter (not even my laser cutter) to cut a solder paste stencil out of some overhead projector transparency..
I smear my paste on.. remove stencil.. populate board... and I re-flow/bake in my a $17 toaster oven from Wal_mart!
There is a tool-chain out there to send GERBER files directly to my vinyl cutter (WAAAAAY better than trying to use the .dxf options you see out there)
I have some write-ups/tutorials on it somewhere.. LOL (Arduino forums..... dangerous protypes forums for source..etc)
xl97
Master Member
Update: ok.. so I couldnt stop thinking about it.. LOL
2 legs of the transistor looked like they could have been not properly joined to the board.. so I hit them both with the iron..
quick check, I could NOT duplicate the 'breaking' of LD3 (but I also do NOT want to press to hard on things)
Question: is there something on the back that would REST the board and/or the audio?
Looks like the APLUS chip on the bottom (top row) might have some solder between 2 pins?
Also seems like it you press/put pressure on the APLUS chip on the backside.. the 'audio' pitch jumps/changes? (higher?)
2 legs of the transistor looked like they could have been not properly joined to the board.. so I hit them both with the iron..
quick check, I could NOT duplicate the 'breaking' of LD3 (but I also do NOT want to press to hard on things)
Question: is there something on the back that would REST the board and/or the audio?
Looks like the APLUS chip on the bottom (top row) might have some solder between 2 pins?
Also seems like it you press/put pressure on the APLUS chip on the backside.. the 'audio' pitch jumps/changes? (higher?)
Thanks MangyDog..
I'll take a closer look at the transistor tonight when I get some time!
I hope you are planning to make a solder paste mask/stencil for those 0402's LOL
I now use my vinyl cutter (not even my laser cutter) to cut a solder paste stencil out of some overhead projector transparency..
I smear my paste on.. remove stencil.. populate board... and I re-flow/bake in my a $17 toaster oven from Wal_mart!
There is a tool-chain out there to send GERBER files directly to my vinyl cutter (WAAAAAY better than trying to use the .dxf options you see out there)
I have some write-ups/tutorials on it somewhere.. LOL (Arduino forums..... dangerous protypes forums for source..etc)
Hehe yeah i got some plastic sheets i can laser cut a stencil into, its going to need it... (forgot what the plastic is but its meant to be fore laser cutting stencils of all sorts so should work.
Im also making a a solder reflow oven at the moment... Im just waiting on a couple of components (ssr thermocoupler) before its ready for final testing bug fixing and programming. With all the 0402s i cant use a hot air gun, they would just blow away. im hoping it would be ready to use by mid next week if the two missing parts come by friday.
still a WIP but I did the vast majority of coding over the last week or two... its just running it to see what i got wrong and what to fix.
I had the pcbs now for about 2 weeks. I really want to get them running to see if 1 they work and i didnt fook up the design and 2 they work............. and i REALLY didnt foooooook up the design.
But also i need to get the prop built as its promised for some one whos been insanely patient with me.
hehe nice, i did a custom stm32 board with an eve chip built on... this was to do some testing for the new display system on the new tricorder. Ill go into it in detail when i have something to show in the old thread... or should i make a new thread... mmmmhmmhmhmmmmm
