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I have a Samsung Note 9 with a weird technical issue that has to do with usb standards. If I plug in the phone to a PC using a USB-C to USB-C cable, the phone will charge and transfer data to the PC. If I use a USB-C to USB-A with the PC, the phone will give me slow charging warnings (much slower than the 500mah) and the PC will not see the phone.

If I use the Samsung charger block with a USB-A that comes with the phone, I will get very slow charging again. I guess there is a handshake issue with the usb a standard.

So basically I can ONLY use USB-C to USB-C cables to charge and transfer data. I'm wondering what could possibly cause this since I have tried saftware reset and changing cables and the phone charger port. The only thing it could be is the motherboard but why would the USB-C to USB-C cable work!?

Did some digging and I have a lead that it could be the OTG circuits on the mobo. I got PCB diagrams and repair guids. enter image description herehttps://www.alisaler.com/samsung-schematics-diagram-download/ This website has a all the documentation on many Samsung phones

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  • \$\begingroup\$ Maybe you didn't understand but I can't use the original cable that came with the phone to charge or transfer data. OTG also doesn't work. \$\endgroup\$ – ryley Mar 18 at 2:20
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USB-A-to-USB-C cables are a bit silly: The resistor which denotes power draw is in the cable itself.

Thus you only need to buy some USB-A-to-C cables of Amazon (or any other retailer), all 3 resistor values are available AFAIK (equivalent to 500mA, 1.5A, 3A).

Sounds like the vendor packaged a 500mA cable with the phone. Correct according to USB spec, but most PCs allow 1.5A current draw without damaging anything.

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  • \$\begingroup\$ I have tried many different cables including a brand new OEM cable. My biggest problem is that I can't use my phone for Android auto because the phone doesn't recognize the car. \$\endgroup\$ – ryley Mar 18 at 2:22
  • \$\begingroup\$ " The resistor which denotes power draw is in the cable itself. " That's right, because that's the cable informing the USB host how much power the cable is designed to handle. The device will then make a request for power over the USB data lines. The host then will inform the device how much power it can draw safely, that being no more than what the host can provide and the connecting cables can manage. \$\endgroup\$ – MacGuffin Mar 18 at 15:11
  • \$\begingroup\$ The cable does exactly nothing on the USB-A (host) side except connecting the wires. Unless it actively monitors current - and not many do - the host has no idea when a device pulls 1.5A or 3A from an USB-A port. Those 3A cables are dangerous IMHO. \$\endgroup\$ – Turbo J Mar 18 at 20:30
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I agree with Turbo J, the USB-A cable you are using just might be the culprit. Have you tried with other USB-A-to-C cables?

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  • \$\begingroup\$ I have used a brand new OEM cable and it does not work. When I plug it in to a windows PC it does not see it at all. With a USB-C to C cable it works fine. \$\endgroup\$ – ryley Mar 18 at 2:23
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I recall this was an issue with some recent Samsung phones which was corrected with a software and/or firmware update. Check with Samsung on if there are any updates for your phone.

The other possibility for your problem is that the phone requires a Quick Charge power adapter for more than a trickle of charge by USB-A chargers. Check what kind of charger you are using. I recall, but I may be mistaken, that Quick Charge uses different USB-A to USB-C cables than is typical. You may need a Quick Charge cable. If your computer is not able to transfer data then that may be a sign you have a Quick Charge cable as those cables are built for charging only. Use a Quick Charge cable with a Quick Charge power adapter, and a standard USB cable with your computer. Using the right cable for the right job should fix your problem.

A quick web search tells me the phone supports wireless charging, perhaps consider a wireless charger as a workaround.

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