Zener diode identification (from a schematic)

HI, hoping for some help identifying the zener diode in the attached schematic of a monitor audio RSW subwoofer amp. Am recapping the boards and noticed this was missing -


Would you have dimensions for the Zener diode?
As we do have a fair number of options that are at 9.1v

Or an idea of the footprint that it would have taken up?

From your image it looks like it would be the same as the ZD11 up and right of the one you marked.

Here’s a pic with other components to hopefully provide size relative to its surrounding - that help?

I think it is the same as the ZD11 however when manufactured they put rtv and/or glue on it making any markings/banding colours difficult to decipher


If you are able to get a length and width measurement of the ZD11 (even approximant) I can use that to narrow the options of the above linked items.

Will do - thanks for your help thus far!!

It’s roughly 1/8” in length and about 1/16”wide

Hello, amooser3, It looks like you have a package of 1206 (3216 Metric) package , I do not show we stock a Zener diode at a 9.1v.

Is the information provided above reference a size or brand or spec?


The general size of the 1206 package type is
0.126" L x 0.063" W (3.20mm x 1.60mm).

Thank you. :+1:

Hi amooser3,

Based on the dimensions you gave, it’s most likely a Mini-MELF (aka SOD-80, aka DO-213AC) package.

Here’s a link to the ones we stock which would probably work. There are very subtle differences between them, but it most likely does not matter in your application.

Thank you so much!
Lastly, the diode has colour bands on it which appear to be brown, black, red and green. I’ve seen charts that decode this for resistance, is this the same colouring system for zener or is this an indication of max power?

Hello amooser3:

Zener diode color coding is an interesting topic. My research tells me there is no standard marking for zeners and most diode manufacturers mark them as they please I found this Color Code Chart and also this datasheet which assigns colors to the voltages, but as you can see they vary quite a bit. The most common statement I found when checking on this was referring to the lack of standard markings, so unless you know the manufacturer of your diode, there is not a foolproof way to determine the voltage.

Thanks so much for your insight. Funny that such a base-level component (building block context) would be so undefined.