Help identifying component

Thread Starter

ZackTheBruce

Joined Jul 21, 2014
4
Trying to repair a Spirent Communications power supply board that is missing this component.


The only markings are a wierd X followed by T13 and then below BKBW.

Any help would be greatly appreciated. Thanks!
 

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THE_RB

Joined Feb 11, 2008
5,438
I have not seen that part before but it is likely to be a MOV.

Photos showing both sides of the board might help becuase we could see what it is conencted to. There looks to be power diodes and a power resistor very close so this is possibly a MOV to clamp an incoming PSU rail?
 

Thread Starter

ZackTheBruce

Joined Jul 21, 2014
4
Whoops! actual attached photo of the back of the board.

Also idk about RV being a designation for a varistor as RV2 and RV3 both have capacitors in that location.
 

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ian field

Joined Oct 27, 2012
6,536
Trying to repair a Spirent Communications power supply board that is missing this component.


The only markings are a wierd X followed by T13 and then below BKBW.

Any help would be greatly appreciated. Thanks!
My best guess would be a polyfuse - a PTC thermistor that is heated by the current flowing through it - at a certain temperature it hits the knee-curve and the resistance rises rapidly limiting the current into the load.

In effect; a self resetting fuse, if you remove the overload it cools down and resumes normal conductivity.
 

AnalogKid

Joined Aug 1, 2013
10,987
It's not Cicada, their logo has sine waves, not triangles sections. This is a transient protection device of some kind. Probably a varistor because of the V in the reference designator, but I've seen tranzorbs and Polyswitch use that package. I recognize the logo but can't place it. Check with Vishay and Bourns.

ak
 

THE_RB

Joined Feb 11, 2008
5,438
He'll send you the board shortly - maybe you have a better X-ray machine.
I do. It's between my ears, finely tuned from 30 years of repairing electronics with no schematics. I can see right through things. ;)

Being a large suppression device next to power rectifiers it should be on power rails and easy enough to trace, even if it requires touching a multimeter probe here and there. :) (For the people who can't see through things).
 

ian field

Joined Oct 27, 2012
6,536
I do. It's between my ears, finely tuned from 30 years of repairing electronics with no schematics. I can see right through things. ;)

Being a large suppression device next to power rectifiers it should be on power rails and easy enough to trace, even if it requires touching a multimeter probe here and there. :) (For the people who can't see through things).
My guess is still a polyfuse (PTC thermistor) - I've seen a few of them used instead of consumable fuses on USB ports.

Dead easy to check - find a board with one on it and heat it with the tip of an iron, if the resistance increases its a polyfuse. A surge suppressor won't have much resistance change till it gets *REALLY* hot.
 
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