Thread: Zener check

What is she out of etc ...

Originally Posted by loopyloo

Hi all,
I have a crook zener here and just want to get confirmation as to what it is.

The only markings on the zener diode is : C155T.
Can't find anything on the net about this number except one site that suggests it's a 15v, 0.5w. Is this right ?

Loopyloo.

Not enough information.

Case type ?
Surface mount, axial or ????
Physical size ?
More than likely 15.0 V 5.0 Watt.

ON SEMICONDUCTOR

755 in stock 18355 deliver in 6 - 7 working days cut-off times

Price For: 1 Each 1+ $0.948 10+ $0.726 100+ $0.434 250+ $0.343

Looks the same as a 1N914. Them red glass lollies.

It's from a Primus power pack for solar lighting system......

It is one of the many cheap noname components produced in asia with no real reference.
These zener diodes can be a pain in the butt and only in rare cases I found a useful marking on the circuit board that conforms to standards, e.g. Z9 can be the ninth zener diode used or mark a 9V zener diode - sometimes you just need some luck
For some cases common sense can be used to determine the correct voltage for them as in a 12V battery powered device you should not find anythig rated for more than 20V in terms of caps and nothing over 15V for other components.
Sometimes you can also follow the wiring and notice there comes something that needs, let's say exactly 15V.
However in most cases with unidentified parts it comes down to luck and good guessing.
Juding from your post I would say a 1.55V zener is not likely and if the marking mean anything in reality a 15V zener would be my first try unless it is pretty clear that the circuit would require a lower voltage from the zener.
If 0.5 or 5W can be checked by the size as a 5W is huge compared to a 0.5W