[NTLK] MessagePad 100 (OMP H1000) Flickering/glitching

Erik Johnson apple.newton at retro.network
Sun Oct 7 03:42:22 EDT 2018

Oh good my message made it!

> Wow. How cool! This is the type of information that usually makes my
>  day. Or, to be more precise, the days in at least the coming two 
> weeks :-)


> If replacing C51 will always fix this problem, you can proudly say 
> that you've done a lot towards keeping the Newton platform alive and 
> kicking. And you'll have saved not only your Newton, but many others 
> all over the world, starting with the three that are currently within
> my reach.

Please let me know how it goes!  I'm still not sure why after all my
searching I found no mention of these by anyone except a vague
"probably" reference to "capacitors" on 68kmla.  I have a dead MP110 on
its way too, but it has known battery damage.  I'll see about that...

> C51, by the way, is part of the LCD boosting circuit. The power to 
> operate the LCD is generated by a step-type chopper-system converter
>  around IC 18. In a nutshell, this converter generates 28 Volt from 
> the battery voltage. C51 is at the end of it. It is supposed to 
> stabilize the LCD supply voltage. I'd assume that the display would 
> behave exactly the way you described if this voltage isn't steady.

I figured it was part of some booster because of the mechanical ticking
noise it was making, much like an inductor being pounded.  And its
proximity to a beefy inductor under there :)

- Erik

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