[NTLK] Power supply check method

Vladislav Korotnev vladkorotnev at gmail.com
Thu Mar 31 11:09:59 PDT 2022

Thank you Victor for checking how a normal one works. Good I didn't risk plugging it in

I wonder what made a lot of my power supply units (somehow not PC built-in ones but
"power bricks") go bad over those 3 years of idle compared to the rest of their life —
I've already messed up an HP Omnibook 800 by blindly trying to power it on to get a bunch
of my stuff out and it went up in smoke. Further checking revealed the PSU oscillates
between +18V-+20V without load and up to +24V (sic!) when loaded while rated for +12V. 

Or are they all just somehow the same age and got the capacitor issues at the same time?

Hopefully at least the one I have somewhere in cold storage still works. If anything
would buying an adjustable adapter and setting it to 7.5V help? (or maybe more and a buck
regulator circuit on top of that)

On Thu, 31 Mar 2022 11:58:42 -0400
Victor Rehorst <victor at chuma.org> wrote:

> I just checked my own Newton 9W adapter with my multimeter, and it read 
> 7.4V.
> Newton 2x00 and eMate 300 units have a 9.1V zener diode protecting the 
> power input circuit. It's been well documented that input voltages over 
> 7.5V run a high risk of blowing the zener diode, at least.
> Don't use it!
> -V
> On 2022-03-31 04:42, Vladislav Korotnev wrote:
> > Hello list, nice to see everyone still around.
> >
> > After a long time I have suddenly got a chance to give my home a visit and so decided
> > to go ahead and power on my gear, including the Newts that I had over the past years.
> >
> > However when checking with a multimeter the Newton 9W Power Adapter, labeled as 7.5V
> > output, produces a 9.2V open-circuit output voltage.
> >
> > Is it safe to use or did it go bad over the years of being unused?
> >
> > Thanks and best regards
> > ----------------------------------------------------------------------
> >
> > http://newtontalk.net
> > http://twitter.com/newtontalk  
> ----------------------------------------------------------------------
> http://newtontalk.net
> http://twitter.com/newtontalk

More information about the NewtonTalk mailing list