Amiga 1200 capslock flashing, no boot.

[jbenam]

Originally Posted by Xtal

No only the A600 has the NE555 reset solution. I have to go through the schematics of the 1200 2B to find some clues.

Cheers. I had the faint remembrance that it didn't have one but I wasn't too sure

I'm really interested in knowing how the reset circuit works on the A1200, so I'll keep an eye on this thread

[Xtal]

Okay, I got some spare time yesterday, so I made some tests.

Power on without anything but keyboard, with or without Kickstart ROMs give a flashing capslock. No output on sync (Composite Video, HSync, VSync).

The computer has been equipped with a Blizzard-030/50 and a external 3.5" harddrive and PCMCIA NE2K compatible ethernet. Everything works flawlessly in another A1200, so no problem there. Keyboard works fine, also tested. All caps measured within tolerances, so I doubt that was a problem. Also replaced some of the radial caps mounted through-hole. A hint there, the A1200 is not RoHS compliant, so it uses tin/lead(/copper/silver) solder, so if you use RoHS (lead free) solder, make sure it's wetting completely since there can be a problem mixing Non-RoHS solder with RoHS compliant solder. And clean out the remaining flux....

Tested with other KS3.0 ROMs (A1200) and KS3.1 ROMs (A1200) and A4000 (no major difference except no PCMCIA support?) No success.

Measured voltage over caps (none leaking / bulged) and exchanged some (almost all) of the SMD caps to equal capacity and equal/higher voltage rating. The caps measured within tolerances though....

So, this A1200 Rev. 2b seems to have gone into Rigor Mortis...

Anyway, I'll try to find a keyboard CPU, fit a socket for easier replacement and see what that leads to. I'll try to keep it documented in the progress of replacing components. (Yes, it's easier to get hold of a PAL A1200 m/b but not as fun :-D )