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Possibly Zener diode identification

Aller

May 27, 2022
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Hi Everyone. I have a shorted diode marked 15A 435. It's most likely a Zener since it was connected with the anode to the ground. I tried to find its reverse voltage value on the internet without success. Can anybody help?
 

Aller

May 27, 2022
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Here are 3 photos, although I really don't know what new this might give you.
 

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Bluejets

Oct 5, 2014
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Thought you might show where it comes from or what piece of equipment.
Just because the Anode is connected to ground doesn't necessarily make it a zener.
Prime example is in a bridge rectifier.
 

Delta Prime

Jul 29, 2020
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In addition to the above stated excellent information
The schematic symbol for the zener diode is
1676022565526.png












While the silk screen designation on the printed circuit board proximal to the mystery component is.

1676022757464.png
It's very good chance it's a house number cuz I can't find it.
 

kellys_eye

Jun 25, 2010
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Could be a transient absorber rather than a zener - particularly if it's connected to ground at one end.
 

Aller

May 27, 2022
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Thought you might show where it comes from or what piece of equipment.
Just because the Anode is connected to ground doesn't necessarily make it a zener.
Prime example is in a bridge rectifier.
Yes, Bluejets, you are right, but in this instance, it's obvious that it's not a rectifier. I jumped to conclusions...This board is a part of the Caterpillar control system. The board number is CAT 106-1154. Does anybody have any insight on this board?
 

Aller

May 27, 2022
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In addition to the above stated excellent information
The schematic symbol for the zener diode is
View attachment 57968












While the silk screen designation on the printed circuit board proximal to the mystery component is.

View attachment 57969
It's very good chance it's a house number cuz I can't find it.
Thank you for your in-depth explanation. I am sure that somebody new to this field will benefit from it. As for me, I am an electronics repairs technician for the last six years, so I know this stuff. The board doesn't have any designators; in fact, it doesn't have any silk screen. The only symbols (generic diode and the "+" signs next to capacitors) are etched from the copper plane and are (I feel) for polarity only rather than any specific markings.
 

Aller

May 27, 2022
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Could be a transient absorber rather than a zener - particularly if it's connected to ground at one end.
Could be, but I think that this board is far from the type of sensitivity this would warrant. This board is a part of the Caterpillar in-cabin control display (a bunch of alarms lights and displays).
 

Delta Prime

Jul 29, 2020
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Thank you for your in-depth explanation. I am sure that somebody new to this field will benefit from it. As for me, I am an electronics repairs technician for the last six years, so I know this stuff. The board doesn't have any designators; in fact, it doesn't have any silk screen. The only symbols (generic diode and the "+" signs next to capacitors) are etched from the copper plane and are (I feel) for polarity only rather than any specific markings.
I could definitely be mistaken considering the horrible photographs taken of the unit. My apologies.
I wasn't trying to beat you up. I'm sorry you took it that way.
 

Aller

May 27, 2022
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I could definitely be mistaken considering the horrible photographs taken of the unit. My apologies.
I wasn't trying to beat you up. I'm sorry you took it that way.
Absolutely on offense taken. I understood that you wanted to benefit some members of this forum who were possibly new to the field of electronics. Your explanation was good, and I would do the same. The diode's very bad quality (dark) photos are due to the markings being barely readable, so I had to play with lighting to show anything.
 

Delta Prime

Jul 29, 2020
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Evaluation: Majority of photographs were not that bad after all.
My Resistance to post further in this thread has been overcome by my Capacity to reason clearly, therefore my final thoughts have been Ohmitted.
 
Last edited:

kellys_eye

Jun 25, 2010
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It's most likely a Zener since it was connected with the anode to the ground.
Can you trace out the cathode end of it? Where does the supply come from, where does it go and any components 'inbetween'? You don't need to dig too deep to discover this but if the cathode end goes to the supply without going via a series resistor then it's a transient absorber (my guess). <edit>transient voltage suppressor.... got the name 'wrong'.

TA's are used in such circumstances too - voltages in ICE equipment are often spikey, more so if a lot of solenoids are in the system.

Equally, if the board isn't used to derive another supply (i.e. 5V) then you could do worse than remove or replace the diode with a 12V zener and see what happens when it is powered up.

Here's a link to typical TVS https://www.littelfuse.com/products/tvs-diodes/automotive/tp1_5ke/tp1_5ke43a.aspx and if you check the details on such devices their normal failure mode is 'short'.

I suggest your device is rated for 35V and 15A - a typical automotive voltage application.
 
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