Bad Zener Diode? | AEM
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tt460
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Last seen: 1 year 12 months ago
Joined: 01/01/2016 - 18:13
Bad Zener Diode?

I have a 30-1900U Universal Race EMS and was having some weird issues with. Pulled the box apart and found what appears to be a cracked zener diode in position ZD7 on the daughter board.

Does anyone know what ZD7 does or what issues it could cause if it's blown?  Also, what specs would I use for a new zener diode to replace it?

In its current condition the EMS starts and engine runs, but I feel like it has always had more sensor noise than similarly configured Plug and Play installs I've worked with.

 

tt460
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Last seen: 1 year 12 months ago
Joined: 01/01/2016 - 18:13
I de-soldered one end of the

I de-soldered one end of the zener diode (to see if I could read any markings on it) and it just fell apart.  I sent this box into AEM a few years back when I suspected something was wrong with it since it has always had sensor noise and they said it checked out fine on the test bench.

Can anyone help me out?

 


 

AEM_NS
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Last seen: 17 hours 48 min ago
Joined: 06/06/2014 - 09:31
That Zener is part of the

That Zener is part of the reverse polarity potection circuit.  That two legged yellow rectangle that's folded over is the resettable fuse that's also part of the circuit.  The diode is a BZX85C20.  Doubt a bad Zener in the reverse polarity protection circuit has anything to do with noisy signals and I also doubt that fixing it would change any behavior of the box.  Perhaps power was reversed at some point but so long as that doesn't happen again, it should be okay.  

tt460
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Last seen: 1 year 12 months ago
Joined: 01/01/2016 - 18:13
Much thanks for the reply.  I

Much thanks for the reply.  I've ordered replacement ZDs and I'll get that one swapped out.  I don't recall ever having power swapped, but I've had this box for nearly 10 years.

Thank you again.