Looking to replace damaged Zener Diodes.

Thread Starter


Joined Nov 2, 2008
I'm looking to replace two zener diodes from my job's Kawasaki 4.0volt screwdrivers. These tools were used everyday but either because of overuse or poor design they have both died in about 3 months. It's been a few weeks now and I've neglected getting replacements for my coworkers that use them. I've torn them apart and have located the same component damaged in each drill but in different locations. I would like to replace the components myself with higher quality components.

The damaged components are labeled as 'Y2'. After searching online and this website, I've found information to identify them as 0.3W zener 12V diodes. They are manufactured in a three legged package but one connector is not used from my understanding and cost a fraction of a dollar a piece. What I am looking to find out is:
1. To replace this with a higher quality part, what factors should I look into? Is it higher power dissipation.
2. Is it possible to use a through hole part instead and solder it where the smt part would have gone since it requires only two connections instead of the three?

I have done a brief search but have not found anything about using through hole parts as smt replacements. If there is info out there on this please point me in the right direction. The reason for wanting to use a through hole part is the possibility of buying a beefier component to take the abuse without failing for a long period of time. Here are some pictures to show what's going on:

I have found replacement smt parts at mouser, one rated at 250mW power dissipation: NXP Semiconductors BZX84-C12,215, another rated at 350mW power dissipation: Fairchild Semiconductor BZX84C12. Would a through hole component with 500mW dissipation be possilbe to install: NXP Semiconductors BZX79-C12,113?
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Joined Nov 23, 2012
Yes, no reason not to try. Drill the holes in the existing pads and stand it up vertically. Easier to solder if you put it in from the back side but if design issues with. The enclosure prevent it, put it in from the solder pad side and solder away. It is also possible to do some creative lead bending and solder the leads to the pads without drilling.

The only possible issue is the you move the poor design down to the next weakest link on the chain. These Kawasaki drills are not exactly high-end (if I remember correctly) so you are not really risking anything.
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Ron H

Joined Apr 14, 2005
Be aware that 'Q' is the standard reference designator for a transistor. 'D' is used for diodes, including zeners. These designations are industry-wide.
Note that each of the three leads on the damaged devices seem to connect to a different node. I think they are transistors.
I think the Y2 designation may be specific to the manufacturer of the PC board. When you think about all the different types of devices that are available, there is no way a 2 or 3 character alphanumeric code could cover all of them.
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Joined Dec 29, 2010
I dont think Q1 and Q2 are zener diodes. According to the datasheet, there is only one zener diode in BZX84C12 between pin 1 & 3. Pin 2 is supposed to be NC.

When you look at your component, the burnt part is 3 and 2. And pin 2 is going somewhere which doesnt make sense....