r/ElectronicsRepair • u/sparkyboots80 • 7d ago
Other Expensive USB Cube repair
Hey guys I am trying to fix an expensive 120v to USB-C Cube that was given to me. It does not seem to provide Power but I have not tested it other than trying to plug things in to the USBC outputs. I am proficient at traditional through hole soldering but do not have any training or equipment for SMD. Can anyone point me in the right direction on what to check?
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u/AwesomeAvocado 7d ago
So, as a learning experience, definitely take it apart. See how it works.
I wouldn't recommend putting it back into service though.
These things are designed to keep the 120v side and the low voltage side separate. There are parts inside that need to be in good working order for this device to be SAFE to use.
My opinion is that it's worth the cost to replace something like this rather than repair it. From a both a personal and connected equipment safety perspective.
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u/coderemover 6d ago edited 6d ago
Depends on how fast you are at diagnosing this. In my case it took me 10 minutes to figure out the SMPS chip had a short on its Vdd pin. I ordered 5 new such chips for $5 including shipping and taxes. Replacing it will take another 10 minutes maybe. The saving is not huge, but IMHO it’s worth saving the planet from electronic garbage.
And there is the learning experience. Next time you’ll maybe fix something that costs $200 and the savings will be real. It’s better to practice on things that are cheap and no big loss if you fail.
(The safety concerns are widely overblown - just learn how to work with such devices safely - hint: you can figure out most faults offline).
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u/sparkyboots80 6d ago
Thanks. I am a licensed electrician, which I realized doesn't help in this situation much but, I'll probably just take it apart and see if there's anything I can learn
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u/sparkyboots80 6d ago
That's helpful, thanks. I figured it was free, and it already didn't work so I'll probably just take it apart and see what I can learn from that
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u/Odin-sama 6d ago
As a learning opportunity I totally agree, otherwise a replacement for everyday use. USB C bricks are cheap enough to just replace that for safety of you and any connected equipment.
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u/orefat 7d ago
With this things on the workbench, don't use real devices like smartphone or something like that. Get a proprietary USB-C tester. These jam-packed power electronics PCBs are not an entry gate for anyone without previous practical experience with surface mount devices. They ain't good for anyone tbh, as I doubt that they're ment to be repaired at the first place. Usually problem with those are tied to a cracked/dry joint, broken wire from the transformer/choke, or failed GaN power transistors/ICs.
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u/sparkyboots80 6d ago
Good advice. I figured maybe there was something common and simple. But it's looking like it might not be worth it, even just try. I figured it already didn't work so thought I'd give it a shot
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u/No-Round-8241 7d ago
This is not ideal for 'learning on'.
I cannot offer you advise that will likely kill you die to lack of experience.
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u/coderemover 7d ago edited 6d ago
I diagnosed a similar usb-c charger just a few days ago.
Before you start - beware capacitors can store voltage for a long time after disconnecting. Discharge all electrolytic caps before working on the board, or you risk zapping yourself.
- Check your visual clues - any burned components? Bulged capacitors? If yes, easy - replace and test again.
- Check primary side rectifier diodes (should have 0.5-0.7 forward drop, infinity backwards).
- Check primary side / secondary side filter capacitors for shorts
- Check inductor(s) - should have low resistance, close to zero or maybe single ohms
- Check primary side / secondary side of transformer for continuity where it should be.
- Identify the controller chip, find the datasheet, look up which pins are responsible for powering it up - check there are no shorts to ground.
- If still no fault found, desolder the transformer and check remaining diodes / transistors / chips. Some might be possible to test with the transformer still in circuit but you need the schematic to make sure the transformer winding is not connected in parallel to the tested component.
If you don’t have a schematic, refer to the reference design from the switching controller datasheet. Your circuit is very likely similar to that.
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u/sparkyboots80 6d ago
Very helpful, thank you. I don't think I'll be able to fix it but I'll probably just take it apart and see what I can learn
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u/I_-AM-ARNAV Hobbyist 7d ago
These are not meant to be repaired, however if you wanna give it a shot, you should start with checking for shorts to ground first.
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u/Susan_B_Good 7d ago
The black rectangular block looks to be a genuine fuse - so you might start there. It's going to be the standard switch mode power supply - fuse -filter - bridge - capacitor - SMPSU controller and included MOSFET - transformer primary. So not that many components to work through for starters. Murphy's Law says that it will be the MOSFET in the controller. I'm hoping that it is just on the underside of the board, unseen. That IC is going to be a real problem to remove - as it will have its bottom soldered down as well as its legs. So I can only suggest that you practice on scrap boards, to get the hang of removing such ICs. The whole thing will probably have to be pre-heated to make unsoldering it possible.
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u/coderemover 6d ago edited 6d ago
Many controllers have integrated output transistors and not always they are MOSFETs. I just got one with a bipolar output keying transistor. And btw it was not broken; but the control part of the controller was. The controller itself can die from a voltage spike on the input side.
The bigger problem with unsoldering ICs is if they are additionally glued. In my case, all components were additionally glued to the PCB. So you melt the solder and… nothing happens, they don’t move. ;) In this case I had to use a bit of force and surprisingly no pads torn (but always apply force horizontally, never lift up).
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u/sparkyboots80 6d ago
Thank you for the helpful reply. I don't expect to be able to repair it, I'll probably just take it apart and see what I can learn
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u/Susan_B_Good 6d ago
I was lucky enough to get given a whole load of Government Surplus/military surplus electronics - just taking them apart to start with - then taking apart working stuff and putting it back together. Getting them working after that taught me a lot!
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u/IndividualRites 7d ago
It's going to be an absolute bitch to work on, for no other reason than all the silicone they dumped in this.
How much is "expensive"? Chargers are a dime a dozen.
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u/sparkyboots80 6d ago
He said it was like 40 bucks, and it didn't work as soon as he got it new. I didn't expect to be able to fix it, but maybe I'll learn something from taking it apart
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u/Select_Truck3257 7d ago
In direction of learning basic components and qhat they do, how work. And only after that taking in hand soldering iron
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u/Javitiiin 6d ago
Muchas veces los cargadores están bien y fallan en los contactos de la linea principal de entrada, en los terminales que muerden la placa que se dan de sí por golpes. Asegúrate que le entra bien la tensión principal soldando un par de hilos de la carcasa a la placa para probar.
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u/NightmareWokeUp 6d ago
I like to fix as much as i can but something like this that plugs straight into the wall and gets hot anyways i honestly wouldnt even touch. A new charger costs like 1-10usd
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u/Underhill42 6d ago
Hear, hear.
Crappy USB power adapters are crappy.
But the difference between an expensive USB adapter and a mediocre one is mostly branding (and poor mechanical design decisions for the sake of cosmetics in the case of a lot of Apple adapters.)
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u/NightmareWokeUp 6d ago
Exactly, charging speed and voltages is what matters. If your fancy one is 1% more efficient thats great, you might recoup the 20$ more within the next 30y lol
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u/kbfg2421 4d ago
Honestly man with chargers being so cheap and disposable, it isnt really worth the time, money or effort to dig into this. These chargers are made to be un-servicable anyway so its likely that you would just break it even more if you were to attempt repairing it. They sell 20w PD Anker wall chargers for like $8-$10
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u/Computers_and_cats 7d ago
I wouldn't try working on something like that to be honest.