The flux used becomes slightly conductive over time and causes all sorts of strange problems.
Jeff Birt (Hey Birt!) From: M100 <[email protected]> On Behalf Of Erik Keever Sent: Wednesday, September 24, 2025 1:36 PM To: [email protected] Subject: SPAM-LOW: Re: [M100] Model 100 came back to life Just curious, what is so bad about the flux? It doesn't seem to be causing problems or corrosion. -- Erik On Wed, Sep 24, 2025, 4:46 AM Josh Malone <[email protected] <mailto:[email protected]> > wrote: Every single Model 100 in the entire world needs the following maintenance: * memory nicad replaced (modern NiMH is fine) * Complete replacement of all electrolytic caps (complete recap) with proper cleanup of leakage and corroded joints/traces * Bath in ~100% IPA and scrubbing to remove factory flux residue Without these things, your M100 is dying rapidly. These are 100% must-do repairs to all M100s now. I cannot stress this enough. -Josh On Tue, Sep 23, 2025 at 11:30 PM Erik Keever <[email protected] <mailto:[email protected]> > wrote: Internal NiCad for sure. It's also possible/probable that the electrolytic caps are failing. Multiple caps in mine (the 1uF ones - the smallest) had failed and peed acid onto the circuit board when I came back to it after many moons. It was bad enough to sever the trace that brought the LCD bias to the display, resulting in a zero-contrast condition. At this point those electrolytics are 40 years old so recap is an excellent idea. On a tangent about the caps... the march of Progress has brought solid state MLCCs within easy reach of all the capacitances up to about 1uF. Just saying, MLCCs age far more gracefully (they DO age though, the high K dielectrics undergo a phase change that's reset by soldering temps), and an 0805 is just the right size to fit across two .1" thru hole pads... -- Erik On Tue, Sep 23, 2025, 6:53 PM John R. Hogerhuis <[email protected] <mailto:[email protected]> > wrote: Yeah if it hasn't been replaced it's probably the internal nicad. They all need to be replaced at this point. -- John.
