DVR Small Hardware Problem

Thread Starter

hazim

Joined Jan 3, 2008
434
Dear,

I have a problem in a CCTV system when some electric shock or electromagnetic effect had damaged 3 cameras and 3 inputs of a DVR. The three cameras are connected to the DVR via UTP cable with video baluns.

The cameras have several burnt components in the board so I will replace the boards.
The DVR have the 3 port's 75 Ohm resistors burnt out but also another paralleled component with these 3 resistors named as S as the resistor is named as R and capacitor as C...etc... so what is the "S" component? some suppression component? with what should I replace it?

The attached image clarify the components.

Regards,
Hazim

 

Attachments

Thread Starter

hazim

Joined Jan 3, 2008
434
But how you know that "S" is a capacitor?? there is a "C" on the board referring to capacitor, but this should be a different component other than capacitor. Also, usually smd capacitors color is brown while these S's are black or dark grey. I think they are something like varistors.
 

THE_RB

Joined Feb 11, 2008
5,438
They will be bidirectional TVS components.

That's a guess, based on seeing similar 3-part setups in other appliances, although I have never seen the "S" designator on the PCB (or don't remember seeing it).

"S" for "Supressor" might be what they were thinking.
 

Thread Starter

hazim

Joined Jan 3, 2008
434
Yes it seems some supressor component, as I found Z-shape symbol under it. Anyway, this is a protection item against high voltage such as varistor as I expect.

I replaced the 75 Ohm resistors but the DVR defected inputs didn't worked. There would be damaged IC's. Better to replace the DVR.
 

ian field

Joined Oct 27, 2012
6,536
They will be bidirectional TVS components.

That's a guess, based on seeing similar 3-part setups in other appliances, although I have never seen the "S" designator on the PCB (or don't remember seeing it).

"S" for "Supressor" might be what they were thinking.
S could be for sidac - apparently a diac-zilla type component.
 
Top