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USB charger suddenly fails to work

I have a universal adapter fitted with 2 USB ports. It has suddenly failed. LED light will not come on and both USB ports are dead.

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I found it very useful as besides charging two things at the same time I used it to plug in devices that have a 2 pin plug rather than the 3 needed by our "UK" type sockets.

I opened to check it out and there is no fuse I can identify and no obvious leaking capacitors or physical signs of any damage. I resoldered some areas to eliminate a dry joint issue.

Why and how did this charger/ adaptor suddenly fail? Can it be fixed?

I have 4 USB port Quick charger (5V 3.5A) that met the same fate.

What's wrong with these chargers? Can this be fixed?

Answer this question I have this problem too

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does the regular plug still work?

an image of the circuitry would help.

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Hi!

for the second board (blue one) I'd start by checking that resistor down near the main input wires. Looks like it's a fusible resistor so it should show close to 0ohms if it's good, next up I'd go ahead and check the mosfet, it's underneath where you see the large solder pads, it has 3 distinct tracks the large ones are drain and source and the small one is gate, If you have a multimeter you can use continuity mode, there should be no shorts between any of the pins, if that checks out fine go ahead and check the bridge rectifier, it's the 4 pin IC on the edge of the board, should not be shorted in any way, go ahead and check any secondary side diodes also. If those all check out then that leaves the feedback circuitry or driver IC which unfortunately is where I usually draw the line, as they're a major pain to get hold of and most usually don't even have an identifiable part number.

For the first board it's the same procedure, however I don't see any type of fuse as you mentioned, not even a fusible resistor, IMO that's a bit of a fire hazard as mains goes straight into the bridge rectifier. The mosfet is also likely integrated into the driver IC hence it only uses that one 8 pin IC. Given that the board is not totally toasted I would think that the fault is on the secondary side not primary (still go ahead and check for shorts around the IC and bridge rectifier etc.. just to be sure), so I would check that big diode right next to the yellow transformer and usb port and see if it's shorted.

Check the capacitors on both boards if you have not done so yet, as they're one of the most likely points of failure.

Great to see a fellow Maltese person on this forum!

Best of luck!

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resistor gives a reading of around 470 ohms on AUTO mode but a mere 1.2 ohms with a loud bleep on the resistance mode

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mofset. the meter rings when testing large solder to smallest solder joints; others show a resistance value 469 ohms each

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4 pin IC - no beeps.

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Glad to be here and getting advice. I love electronic stuff but never had the opportunity to learn much. I like restoring things and bringing things back to life..... including humans!!! :)) Which explains my career in medicine.... now just retired.

I am curious as to who you are - you are Maltese too by the way you expressed yourself.

I am also helping to put my country on the map with the development of virtual pipe organs from real recorded pipe sounds of actual instruments (http://mhpo.epizy.com) a projected started around 10 years ago.

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Everything checks out, I'm a little suspicious about the MOSFET since you said gate to drain or source beeps, does it beep and then stop or continuous beeping? What resistance does it measure across those pins? Usually if it were bad then the resistor would blow but that's not the case so it might be ok.

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No clicks.... at least not that I can hear.

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Plug works as a normal adapter. It's just the USB ports that are dead.

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I already replaced the capacitors: no change; and a resistor..... no change

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do you hear a faint clicking when it's plugged in? if so, it might be an issue with the transformer

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@markbugejamd 2nd image IC HC2702 what voltage do you get on pin 1 (that is the one that has the mark (dot) on the IC), pin 4 (last one on that row)? What voltage do you have on the top row each pin? Set your meter high to check what voltage you have.

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@markbugejamd same image, component MB10F is obviously a rectifier. What voltage (DC) do you have on the - and + contacts. What voltage (AC!!!!) do you have on the bottom ~ contacts. Set you meter high, (what are your outlet voltages 220-240V?) just in case.

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How exactly do I use my meter to check these pins out? What to I test them against? In the case of MB10F there are + and - so: red meter lead to + and black lead to the -. Our AC voltage is around 240V.

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PS I have a ANENG Smart Multimeter 620A

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it may be an overheating failure or just these ones are low quality

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@sparkleman welcome to iFixit. Here is a quick note. Always reflect on if your answer will help the OP to repair the device in question. Now, your answer could be spot on, but you are not telling us how to check, what to check and how to repair it. So, expand on your answer otherwise, it's a comment.

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Mark Bugeja MD will be eternally grateful.
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