[NTLK] Newton Repair Question

[Frank Gruendel]

> You would not happen to know the load a newton normally draws on the 
> supply?

That depends on what the Newton is currently doing and on whether there's
power-hungry hardware in the card slots or attached to the Interconnect
Port. If no additional hardware is connected and the Newton is doing nothing
except being powered on, the current should be about 70mA. Installing
NewtTest from the software section of the web site in the signature will
provide you with the exact value.

> If so I may give it to my ETs to power up under load and monitor on 
> scope for a few days until I feel comfortable with it again?

The adapter is rated at 7.5V 1.2A. Assuming that it adheres to Apple's very
own requirements for Newton 2x00 power adapters, it must provide a foldback
characteristic. This means that the power adapter is supposed to reduce the
voltage if the current would exceed the specified maximum. Reducing the
voltage will reduce the current until the specified maximum is no longer
exceeded. This means that these beasts will even survive being shortened out
for a longer time, because even in this case the current wouldn't exceed
1.2A.

So if your ETs can make a variable load from 6 Ohm to about 100 Ohm that
won't go up in smoke if a voltage of 7.5V is applied to it, they should be
able to test the power adapter just fine over the whole range from the
Newton idling along up to the Newton drawing the maximum current possible.
Of course, a positive result doesn't mean there can't be some intermittent
failure with your power adapter. However, I've never heard of such a failure
or found it in any power adapter I've ever had on my workbench. These beasts
hardly ever die. In the rare cases they do, the culprit is almost always the
cable or the connector. If I had to take an educated guess, it would be that
the ship's power supply generator temporarily sent a voltage to the wall
outlets that was higher than it should have been. Unless, of course, the
problem was simply caused by C150 failing out of the blue. These things do
happen, although in my experience not very often.

> Thanks for the input.If you give me your address I can ship it to you 
> for parts if you still want such broken things as your site says?

Thanks for the offer. Yes, I'm still looking for parts. But why not send it
along with your Newton! I'm going to buy a couple of Stefan's untested
mainboards anyway. There'll certainly be at least one among them that works.
So unless you are in a big hurry (my to do list is somewhat long at the
moment), I'm pretty sure I'd be able to fix your Newton at a reasonable
price. Or maybe even for free, if you include some dead iPod or iPhone
hardware. My
learn-to-fix-these-beasts-because-you-might-no-longer-have-a-steady-job-soon
-quest is in full swing :-)

Newtons never die. At least not completely...

Cheers

Frank

-- Newton software and hardware at http://www.pda-soft.de