So I'm starting this thread after troubleshooting my Mimeo.
I had a problem where at first it couldn't load basic anymore, then I got it to load basic (bad ram chip) but after about an hour basic would not reload (E000R or E2B3R) unless I cycle the power and reload basic. It passed all memory tests for E000 and lower memory using Mike Willegal's memory test program for at least 100 cycles each.
So what was it...
Well after realizing my radioshack multimeter can't measure down to 47pf accurately and putting a scope and logic analyzer on the 74123 among other chips I saw some time drifting, I replaced the mylar cap and also decided to replace the B13 -5V decoupling cap (it measured spot on, but I replaced it with one that measured high)
It solved my problem and after about 8 hours of use, never once did I experience a problem.
So why is this thread called "replica problems vs the real thing"?
I never had this issue on the real thing, the mica caps are usually solid. I know I have been reading in the past that 2504V chips have been bad in Mimeo and Newton setups and that some people have had other problems. The only real Apple-1 I know that had a problem with 2504 chips was Wendell Sander's back in the 1977ish time frame when Steve Jobs replaced one under warranty for him.
There are other weak points in the real Apple-1 like board warping and the 7451 or 74123, but frankly too many potential issues to list here to send people with a Mimeo or Newton problem down a troubleshooting rat hole that don't apply to them, but I was wondering if people can post a brief description of the issues they have had with their replicas and what the solutions were. Please don't point to a thread, just summarize in this one. I'm hoping this new thread can be a quick cheat sheet to help people out in bringing up or troubleshooting their replicas.