The attached is the back of a USB hub that stopped accepting power from the wall wart. I took it apart because I can't help myself and was wondering what the white stuff was on the hand solder on the board mount USB sockets. It's easily scraped off with a finger nail and I assume its flux residue, except that there's the more normal flux residue there as well and it's only on the pins that're connecting the socket case to the board.
Any ideas?
Also it's quite a juxtaposition between the supreme tidiness of the oven cooked smd and that messy hand solder. Though, that said, I do miss the opportunity to scavenge parts. I can barely see some of those capacitors, let alone desolder them for reuse...
Any ideas?
Also it's quite a juxtaposition between the supreme tidiness of the oven cooked smd and that messy hand solder. Though, that said, I do miss the opportunity to scavenge parts. I can barely see some of those capacitors, let alone desolder them for reuse...
Attachments
Hi I know this from cleaning water based solder flux also with water.
If it stopped accepting power maybe the DC jack came loose or has very tiny cracks in the solder joints? It happens.
If it stopped accepting power maybe the DC jack came loose or has very tiny cracks in the solder joints? It happens.
No, and not as far as I could see. The plug looked ok and was chucking out enough power and the hub functioned on host power provided there was nothing too demanding plugged in. The power socket looked ok too.
I was just curious why the white was only around the socket support pins. I'm not up on industrial soldering and thought there might be something to learn.
I'd planned to harvest a few of the usb sockets just in case I might need them (though for what I can't imagine). Otherwise it'd probably have gone straight in bin.
Did you measure?
The white stuff may also be from water based flux and hand soldering without cleaning. The smoke sometimes has this consequence. Not easy to remove.
The white stuff may also be from water based flux and hand soldering without cleaning. The smoke sometimes has this consequence. Not easy to remove.
They might have hand-soldered the connectors. Probably used solder with no-clean flux. You don't technically have to clean no-clean flux off the board, but it's generally a good idea, at least in sensitive circuits. As you can see the flux residue can attract stuff and react with it.
Tom
Tom
Output from power plug to board seemed ok. After that, other than academic interest, it was going to cross the line into time-sink. So I decided to bin it and added the wall wart to my collection of wall warts.
If I get a few more I may open a museum...
The wall wart museum 😉
The law I found out the hard way is: “superfluous wall warts that end up in the bin are needed 1 day later”.
The law I found out the hard way is: “superfluous wall warts that end up in the bin are needed 1 day later”.
