JB7 dead USB port

[Oliver Sachs]

Hi!

I have a question regarding a defective JB7. It belongs to a friend of mine and I had a look at the device.

The problem is the following: The USB port no longer works. No matter what I connect, there is no message, nothing happens. My friend has another JB7, on it the USB devices work....

Maybe someone has the idea?

Is it most likely an electrical defect or is there a possibility that it is cold solder joints? I have photographed the solder joints once, maybe you can see something?

Best regards from Mannheim, Germany

Oliver Sachs

[Daniel Taylor]

Based just on what I see in that picture, the four larger solder joints next to the connector look pretty good.  The other ones it's hard to tell.  And there may be additonal solder joints on the other side of the circuit board.

I would try unplugging the connector and then plugging it in again several times to try and break through any oxidation that has occurred.  Beyond that, it seems likely that one of the parts has failed.  Do any of the nearby parts look damaged or burned?

Unless you have a circuit diagram, and a parts layout diagram, and appropriate test equipment, it's probably a job for a professional.

[Peter Lowham]

Hi Oliver,

It might just be that the 5 volt supply to the USB socket has died.  It would be worth plugging a powered USB hub into the JB7 then plug the USB stick into the USB hub.  The powered hub would provide the USB stick with power and the JB7 might then see the USB device.

Regards,

Peter.

[Oliver Sachs]

Hello Daniel, hello Peter,

thank you for your assessments!

So I will first connect a powered USB hub, maybe that will fix the problem.

If that does not lead to the goal I will plug and unplug the connector several times to eliminate any oxidation...

I'll be in touch soon and report :-)

Best regards

Oliver

[Peter Lowham]

Hi Oliver,

Good luck!

Regards,

Peter.

[fred.w....@gmail.com]

I would reverse the order of the tasks ie 1 try and remove oxidation 2 use a powered hub

Because if it is oxidation then even with a powered hub the signals may not get through!

Fred

On Saturday, 7 August 2021 at 20:58:45 UTC+1 kolops...@gmail.com wrote:

[PMB]

Hi Oliver,

I think you will find that the 5V supply to the port has failed and the powered Hub will prove this or not.

Paul

Brennan Support.

[martini...@gmail.com]

OK U6 will be blown.. Common failure.

Some JB7 display boards have this fitted some dont.

If the board does not have U6 fitted then an inductor is fitted at L3

U6 is a MIC2009A-2

L3 is a BLM41PF800SN1L

My preferred option of repair is to remove U6 and install the inductor in the position L3.

Just for information U6 is configured to limit current on the USB port to 1A maximum.

Use this information at your own risk.

Cheers.

[Oliver Sachs]

@fred 

Thanks, I thougt the same, but I am a little hesitant to cut the locking varnish of the plug without knowing if it's worth the effort...

@paul

Thanks Paul, that's encouraging!

@martini

Ok, thanks, I'll have to translate this first :-)

(I am a trained radio and television technician, but I have only worked in the profession for a short time.)