Unknown component on comunications board

[eucosta]

Hi,

I damaged a component of a device that I'm not quite certain what it is. It's situated between the USB female connector and the chip responsible for the signal conversion to USB levels. It's not any of the resistors or capacitors of the conversion circuit.

Here's an image of the component:
https://goo.gl/8gfhS

Can anyone help me?

thanks

 

[tvtech]

Welcome to ETO.

There are three on the blurred photo...which one is it?

Regards,
tvtech

 

[KJ6EAD]

They're all capacitors, probably all the same value. Measure them with a meter to find out.

 

[wkrug]

Because it will be near an input, it can be a Varistor ( Overvoltage Protection ) too.

 

[eucosta]

@tvtech - the three are the same componente.
@KJ6EAD - they are not capacitors..
@wkrug - is there anyway to verify if they are Varistors?

 

[Nigel Goodwin]

@tvtech - the three are the same componente.
@KJ6EAD - they are not capacitors..
@wkrug - is there anyway to verify if they are Varistors?

You need the service manual, and read what they are from that - SM components are almost impossible to identify otherwise.

My vote would be for capacitors though - but no clue as to value, even if they are.

 

[WTP Pepper]

Transorbs. To prevent excess static blowing the interface. I use them myself. I can dig out the exact one I use if required. I know they are made by Vishay.

Capacitors would slug the interface especially at full spped (USB2.0 @ 480Mb/s).

Transorbs appear pretty non existent electrically until there is too much static and then kick in to protect the equipment. Capacitors would have a progressive effect due to their frequency response.

From the PCB shown, they appear to be on D+, D- and Vusb to ground as best as I can tell which is the correct way to do it.

1=Vusb, 2=D-, 3=D+, 4=n/c, 5=0v

 

[tvtech]

Hi WTP

I learn't something new today. Thanks for the info. I found this about Transorbs: Please see attached file.

Always good to learn. Reliably.

Cheers,
tvtech

 

[KJ6EAD]

It's a new one on me too. I didn't know they made transient voltage suppressors in that form factor. Yours look like 0805s but they're making them down to 0402. Here's the AVX catalog page.

https://www.electro-tech-online.com/custompdfs/2012/07/sguard.pdf

 

[eucosta]

Thanks for the info.
Could you help me choose one?
I don't have any technical info of the board.... is there anyway to measure the components that aren't damaged?

Thanks once again

 

[KJ6EAD]

You could measure the capacitance to see if it's in the vicinity of 80pF but there's only one model in the catalog that's the right size if it's an 0805 size (0.08"L X 0.05"W).

You could check Digikey or Mouser to see if there are similar offerings from other manufacturers such as Murata or Vishay.

 

[WTP Pepper]

A transorb if blown and causing problems then it will have a load or short impedance. I will dig out the exact part when back tomorrow. We used to have blown USB interfaces to a micro on a weekly basis until we started adding them to the circuit.

To my knowledge (I am on a different project now) we have never had a failure since.