Re: [NTLK] newton 2100 power fried?

From: Johannes Wolf (mp2100_at_mail-gw.estec.esa.int)
Date: Fri Aug 08 2003 - 07:55:56 PDT


Ok, that explains it.
But if you measure 0.615V in one direction that means it is NO zener diode.
(If the diode is ok, the other direction should indicate a voltage somewhat
near the battery voltage of your meter)
The diode should then be switched in SERIES to the power jack,
since the zener would be in parallel...

Cheers
Johannes

> -----Original Message-----
> From: newtontalk-bounce_at_newtontalk.net
> [mailto:newtontalk-bounce_at_newtontalk.net]On Behalf Of Jeff Sheldon
> Sent: Friday, August 08, 2003 4:07 PM
> To: newtontalk_at_newtontalk.net
> Subject: Re: [NTLK] newton 2100 power fried?

> On Fri, Aug 08, 2003 at 09:30:56AM +0200, Johannes Wolf wrote:
> > On my logic board I can CLEARLY read
> > KNP
> > 78
> > and then something like a brand, looking like TI.

> I was referring to a diode check via a voltmeter. I'm sure the unit
> does handle ~7.n volts as it's connected directly to the power socket.
> So essentially there was not much reason for me to post since all
> I really did was verify that my diode was in good condition :)

> > But I am rather sure that this must be a zener.

> Zener diodes can usually handle a reverse voltage as well which doesn't
> seem very useful here. If you're pretty sure, then I'll go with your
> judgement.

> > What do you mean with 615 mV? I could understand if it was 615 mW...

> It helps to first understand that I'm having insomnia problems, which
> isn't a good combination with a mailing list. It's actually an issue
> of ohms since a voltmeter's diode check measures in resistance.
> Essentially what I was doing has no merit here, but it did indicate that
> my diode didn't suffer from heat death. Hooray me.

> -Jeff

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