[Elecraft] Help! Rescue me from stupid error!

[george fritkin via Elecraft]

There is nothing mechanical about a ZNR.  The electrical equivalent is back to back Zener diodes with a capacitor.  Some people call them Transzorbs or MOVs to get by trade marks.  The ZNR is a Panasonic trade mark

George, W6GF


On Tuesday, September 9, 2014 10:54 AM, "Charlie T, K3ICH" <pincon at erols.com> wrote:
 


A 'ZNR" is a Zinc Oxide non-linear Resistor.  It is the mechanical 
equivalent of a Zener Diode.  It is a bidirectional (AC) device that will 
conduct when a certain level of voltage is applied across it.  They don't 
typically have as sharp a "knee" as a real Zener, but are very effective for 
what they do.  Basically , a voltage surge or transient  protector. 
Hopefully, they worked but are probably blown and should be replaced.

As for the rest of the stuff, I'm sure you'll find some more (inexpensive) 
things to replace and the system will come back to life.

Good Luck on the repair, Charlie k3ICH


----- Original Message ----- 
From: "Vic, K2VCO" <k2vco.vic at gmail.com>
To: "Elecraft Reflector" <elecraft at mailman.qth.net>
Sent: Tuesday, September 09, 2014 1:23 PM
Subject: [Elecraft] Help! Rescue me from stupid error!


>I just did one of the dumbest things I've done since I tried to swim across 
>the Susquehanna river with all my clothes on. I survived that, but I need 
>help with something else.
>
> I just turned on a computer plugged into 230v with the switch on the power 
> supply set to 115v. Result: bang, smoke, house breaker (16a) pops.
>
> I took the power supply apart (it is a funny size so I have little 
> confidence I could replace it). I found two obviously bad components: 1) 
> an 8a fuse -- no problem. 2) something marked znr1 on the board, a 
> component wrapped in heatshrink tubing. It was completely destroyed. Next 
> to it is a similar part labeled znr2. I haven't removed it yet -- 
> so I am not sure it is good. It might be the same as the first one and it 
> might be marked under the heatshrink.
>
> There is a bridge rectifier nearby which checks good. All traces look ok. 
> I am hoping there is someone out there who is familiar with these supplies 
> who can suggest what these are (zener diodes? What voltage?)
> The board is made in such a way that it is difficult to trace the 
> wiring -- but these parts are right near the power input.
>
> -- 
> Vic, K2VCO/4X6GP
> Rehovot, Israel
> http://www.qsl.net/k2vco/
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