Forum: Analog Circuits How to identify a broken zener diode?

von Lernend B. (Company: KUKE Electronics CO., Limited) (lernend05)

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Hi, all
Something about Zener diode. I have found that the door lock switch of 
my '98 Hyundai Accent has been damaged by water (sealing issues). I used 
Wurth Contact OL to remove rust but one of the components of the board 
has got broken while I was trying to remove the rests of the product 
with a piece of paper. I believe I can carry out the soldering work but 
I cannot identify the broken component. My searches (according to 
Testing and Distinguishing Zener Diodes Overview, content source: 
lead me to believe it is a zener diode, but what kind? There are no 
markings on it.

I have thought about asking the local shop to give me a selection of the 
most common types and go the trial and error way, but I am afraid I 
could fry other thing... So, could someone guess, by the pictures of the 
board, what kind of component I need to have all the doors of my car 
closed in one move like in the old good times?

Thank you in advance.

von MaWin (Guest)

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Buy a salvaged door lock assembly.

You do not have the circuit diagram of your pcb, so you will not find 
out the correct replacement part, if it is a zener diode at all and in 
case it is, what the correct value will be The old part is broken as you 
say so you can not measure.

Ok, the other door may have an identical pcb so you may be able to 
measure the part from there.

But as you said, you tried to make it functional by oiling, the door 
lock assembly is in bad conditions anyhow and can be replaced anyway.

If the zener is color coded, you may find the type name here:

von Keiler (Guest)

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If the circuit isn't too complex we could have a guess or estimation by 
good pictures. Maybe that value isn't too critical or maybe it is 

Put the PCB on the kitchen table, big room light on, "good" 
camera/recent cell phone cam ~50cm from above, slightly next to directly 
above to avoid mirrored light spots in picture. Play with flash.
Front and back.

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