[Meyvn]

I have a very slight hiss in the left channel of my Aleph 3, and Pass said to replace a zener diode in the left channel. I've found the output board, but I unfortunately don't know how to recognize a zener diode amongst the others. Anyone care to explain the difference in appearance?

 

[amb]

A zener diode looks just like an ordinary small signal diode. If the label on it (with the part number) is legible you could use that, otherwise, you'll just have to trace to it by corrolating the schematic diagram to the circuit layout.

 

[khbaur330162]

Zener diodes do look a lot like regular diodes, however, they are usually made of some sort of glass/clear material, and on the inside they are sometimes red. It isn't so with every case, however it is with many. If you're confused, I could take a picture for you. I know there's at least one somewhere in my PPA...

 

[error401]

Quote:

Originally Posted by khbaur330162 /img/forum/go_quote.gif Zener diodes do look a lot like regular diodes, however, they are usually made of some sort of glass/clear material, and on the inside they are sometimes red.

As are most small signal diodes

. If you can't read the model number and can't take it out of circuit to test with a diode tester, it's pretty impossible to identify them conclusively. If you're picking up a random circuit board, chances are good that your glass packaged diode isn't a zener.

That said, your comment does have merit in this realm, because small signal diodes aren't generally used in the circuits we're building here. Rectifiers are generally higher current and come in the black plastic packages. So, at least for audio equipment, if the number of zeners in the circuit equals the number of glass packaged diodes, it's basically a sure thing. I don't have a schematic for the Aleph 3, but it probably only has a single zener and no signal diodes, so it should be easy to find.

In case you need it, a picture of some glass packaged diodes here