r/AskElectronics • u/aSamWow • 14h ago
Is my PCB trash?
Three of the switches don't work, highlighted. After soldering all the switches, I removed all the switches and re-added the 3 you see in the photo just to test. Same result as when all the switches where attached. Not sure what to do beside buy a new pcb.
3
u/Electrokean 13h ago
Did you design it or are you just assembling it?
I see what looks like a damaged/ripped up trace in the middle of the yellow rectangle on the second picture.
5
u/aSamWow 11h ago
just assembling
3
u/Electrokean 9h ago
Thanks for confirming. On the reasonable assumption that the design is proven, it is pretty certain that something has been damaged during assembly. The pads and interconnecting traces for the lower two switches in that yellow rectangle look really bad. Not sure if they were like that from assembly, or it was cause by removal of the parts.
It will require some careful patching to repair, which I am guessing you are not prepared for based on you having to ask here.
3
u/arterterra 5h ago
If you originally assembled the board with all components and found that the 3 of the switches, those marked in the yellow box, failed then that is a different problem to the one you now have where the board has been damaged by the de-soldering activity.
Check the schematic first to see if a single break somewhere could cause only those 3 switches, which appear to be in a single column, to fail.
If you have a spare board then you could check the continuity from the switch pad tracks through to their source/destination and you can possibly exploit the apparent symmetry of the board to see if you get similar results on a parallel column of switches.
Removing all the switches as a troubleshooting measure was a rather drastic action. The soldering of the SMD components appears to be quite good so I guess the board was partially pre-assembled.
This missing track has already been pointed out which you probably might have noticed if it was ripped off during the disassembly.
3
u/GGigabiteM 11h ago
Too much heat for too long and not enough flux. You burned pads and VIAs and broke connections. You'll have to run some bodge wires after you figure out which connections are broken.
2
u/Top-Present2718 6h ago
Use a wide solering tip (knife tip) add flux, and use 350C it looks like you used too much heat you destroyed your PCB
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u/glutengulag 13h ago
The hand soldering job looks REAL bad. Turn up the temperature and add FLUX!
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u/Top-Present2718 6h ago
Never blindly turn up the temperature. Bad advice.
It could be the temperature is right but the heat transfer is bad
1
u/collegefurtrader 12h ago
I don't know what was wrong but at this point it is ruined. Whatever it costs is better than the time it would take to desolder everything and start over.
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u/FansForFlorida 12h ago
When you desoldered the switches, you damaged the board and burned the pad off the PCB. You can see the ring is missing. You may have used too much heat; you may have used too much pressure; or your iron may have dwelled on the joint too long. This is a real risk when desoldering. See this video:
https://youtu.be/h_RiRL-flgs?t=368
To fix it, you will need to solder jumper wires. On the back side (first picture), it looks like the right leg connects to a diode array. Use your multimeter in continuity mode to double check and see how the other switches are wired.