Ed,
Corrosion is a sure sign of leaking electrolytic caps. I did a video on a recap, link below. In the description is a link to a PDF with a color-coded capacitor map and part numbers for replacement caps from Mouser. https://youtu.be/IGTdNMx1V1w Jeff_Birt (Hey Birt!) From: M100 <[email protected]> On Behalf Of Ed Graffius Sent: Friday, May 17, 2019 9:22 AM To: [email protected] Subject: Re: [M100] Have a question about my M100 thanks guys....I have not used a listserv in decades so forgive..lol ok, opened it up and the nicad has 4.8ish volts on it. got a 6v PS and batteries in, have contrast wheel middle of the road and memory switch is on. I probed R127 and the collector of T21 and got 122Khz oscillation. Sound reasonable? I probed VDD and get 5.something volts. VEE gives me -.7v which is slightly less than the spec of -5v, this is all with respect to the transformer output ground. D15 (1S2076) appears to be badly corroded and Vf is 1.9v (all other glass silicon is in the .521-.560 range which I expect. I think this negates the efforts of zener D14. Theory: lack of -5v prevents the LCD from lighting up? so I was gonna tear it further apart and replace ALL the 1S2076 (35v, 450ma, 250mw) with either 1N914 or 1N4148 (much superior) - I dont think I have to Vf match any of them? btw - the <enter>, 'B''E'E'P' <enter> works, so that means the CPU is CPUing? -----Original Message----- From: Josh Malone <[email protected] <mailto:[email protected]> > To: m100 <[email protected] <mailto:[email protected]> > Sent: Fri, May 17, 2019 9:49 am Subject: Re: [M100] Have a question about my M100 On Fri, May 17, 2019 at 9:44 AM Stephen Adolph <[email protected] <mailto:[email protected]> > wrote: > > power on, > hit enter > type BEEP then enter > > if you hear a beep, your machine is running. Maybe with no display. I'd suggest opening it up pronto and removing that memory battery. Just snip it out if you don't feel like soldering. If it's completely dead, it can drag down the voltage rail to the RAM and cause system failure. This often presents as having to let your memory battery charge overnight (provide system power via DC or batteries, switch memory power on and wait) before it will boot. If you remove the memory NiCd entirely you eliminate this potential problem. Plus, it needs to come out, anyway. (https://twitter.com/48kRAM/status/1082807102714904576) -Josh
