HereLink Air Unit Reverse Polarity Protection

Hello All,

I think i have fried my HereLink Air Unit by accidentally reversing the input voltage polarity (powered up from a DC power supply @ 7.6V). The air unit does not turn on LED-2 (Right) anymore when connected with correct input polarity. As per the user manual this means “Air Unit is not Powered”.

I tried to connect the air unit with a computer using the micro-usb (debug/upgrade) port and noticed that LED-2 turns On first for 3s (yellow) and LED-1 turns on after 1 second (Yellow) and both LEDs turn off simultaneously. The pattern repeats every 10 seconds. Input Power is not connected and both UART and HDMI inputs are connected to Air Unit.

@philip: Is there any way to recover the air unit? Can i purchase an Air Unit separately?

I also want to ask if there is any kind of reverse polarity protection & out of range voltage protection implemented or planned for the future?

Waiting for some good news :frowning:

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How long did it stay in reverse polarity condition. I think power line plug was ruined! Check it again by voltmeter

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Hi @Banme_RC,

Not long, anywhere between 5-10 seconds. I tried to check the resistance across power input pins after the incident and it shows an open circuit.
Please guide me on how to check the power line plug using voltmeter. I have the Air Unit opened already.

Many Thanks.

Hello All,

I am desperately awaiting some information regarding the extent of damage that occurred due to reverse polarity and possible repair methodology. Anyone who has experience with the Air Unit electronic circuit please help.

@philip Is there any document/circuit diagram that might provide some information on hardware troubleshooting of Air Unit.

@Banme_RC, Please guide me on how to check the power line plug using voltmeter. Is “Power line plug” the connector that we apply power to? Or is this some electronic component on the board itself.

Your support is much appreciated.

Unfortunately we don’t share any information on the internal workings of HereLink.

If it doesn’t respond, then it’s most likely dead unfortunately.

Who is your reseller? We can see about getting just the air unit replaced rather than you having to buy a full set.

Im wondering if today somebody is designing an electrical circuits without RPP. Its a basic fundamental of designing moder electrical devices. Can you please share an information of the device contain any protection or not. Thats important I believe and not a secret information. Bcs if there is no protection it may happen also to anybody else.
Best regards Peter

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Upload a detailed picture of the PCB from both sides. But if there is no RPP than there is no help bcs I believe that there is tiny SMDs.

Maybe you can change a voltage regulator maybe not. Just upload the picture in high resolution thats important.

BR Peter

Please contact your reseller, we absolutely do not support user repairs of this item