Re: [NTLK] newton 2100 power fried?

From: Jeffrey D. Knapp (jeff.d.knapp_at_verizon.net)
Date: Fri Aug 08 2003 - 14:38:54 PDT


Taking off the diode yields the same results - starts up, shuts off,
etc.

The other side of the board doesn't show any signs of charring. Would
it be as simple as to get a new diode? (where? Radioshack?) and solder
it on?

-----Original Message-----
From: newtontalk-bounce_at_newtontalk.net
[mailto:newtontalk-bounce_at_newtontalk.net] On Behalf Of Johannes Wolf
Sent: Friday, August 08, 2003 10:56 AM
To: newtontalk_at_newtontalk.net
Subject: Re: [NTLK] newton 2100 power fried?

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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