[NTLK] MessagePad 100 (OMP H1000) Flickering/glitching screen, no/low sound fix

Forrest newton_phoenix at mindspring.com
Fri Oct 5 20:51:00 EDT 2018

Sounds much like the problem that often plagues Macintosh SE-30s, known to those of us lucky enough to own one, as “Simasimac”.

Here’s a link:

Basically, “jailbars” on the display screen—a pattern of horizontal bars and no chime at startup, caused by leaking can capacitors.


Sent from my T-Mobile iPhone 6S Plus

> On Oct 5, 2018, at 9:40 AM, Erik Johnson <apple.newton at retro.network> wrote:
> I recently purchased a defective Original MessagePad for a good price hoping to fix it blindly.  And I did; 2 compact electrolytic capacitors inside had leaked and gone bad, there are 3 in total inside the device but 1 is not the typical compact/surface-mount kind that goes bad and can probably be ignored safely for now (My LCR meter showed it well within spec).
> Symptoms?  On power-up the screen is garbled and glitches terribly with occasional flickers of the newton logo and eventually sometimes showing calibration text/crosses - but mostly just random lines and black bars.  Also no start-up chime.
> When first removing the back cover C1 had a white fog around it, it's a surface mount and is located right next to the speaker wires.  Original value is 100uF @ 4V.  I only had 100uF @ 25V on hand with a slightly larger 6.4mm diameter body and it fit fine. After cleaning the residue off with isopropyl alcohol and replacing it I got sound - a start-up chime!  But the video was still broken.  In my LCR meter C1 still measured 100u but with very high ESR (almost 1K)
> All the other capacitors visible are tantalum solid-state caps and should be fine.  Plus the one obvious through-hole cap that isn't the compact type to go bad, typically.
> So I removed the logic board to have a look at the other side; and lo!  One more surface-mount electrolytic not too far from the display ribbon also with residue around it.  C51, valued 3.3uF @ 35V.  I had 3.3uF @ 50V on hand (4mm dia, original was also 4mm.  I test-fitted a 5mm and it also fit, but 6.4mm cap did not allow the board to sit flat).  Clean and replace.  Reassembled. And I have a beautiful working OMP now.  Useless handwriting --recognition-- mutilator and all.  C51 did not register on my LCR meter at all, completely bust.
> Pictures here https://imgur.com/a/69J7YWl
> -- 
> - Erik
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