[NTLK] MessagePad 100 (OMP H1000) Flickering/glitching screen, no/low sound fix
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
More information about the NewtonTalk