What are these?

[gunnadoo]

hi, i have been playing around with a 10A psu to try and learn. thinking the lm396 reg had shorted i tried a lm317 and still had a short . so by trial and elimination , i traced the problem to this "zener" looking thing . the regulator seems to work ok without it , but i would like to know what it does. it is connected between + output and neg rail . the other black "diode" type thing [paralled with light bulb] is on a different set of output wires.which won't be used , but i am curious. it measures 1-ohm each way. sorry for any confusion

 

[kellys_eye]

Transient suppressor - rated at a value to limit either the output being over-voltage or to protect it from an externally supplied voltage exceeding its rating (capacitors on the output terminals).

If it's shorted then it's done its job! Replace with suitably rated equivalent if you can't find the details of the original device.

 

[gunnadoo]

thanks, i did lots of googling and there is a myriad of different types of suppressors but i couldnt find anything which looks like the above. without really knowing what i am looking for, would something like a tvs diode [1.5kw EL 18 CA] do the job. the unit is 15 V max output.. thanks