Hmmmm... it connects to F3? Now that's odd, haven't heard of that one. Yup the ROM is 64k, so it's a straight memory upgrade (ROM was always socketed). The area around E3 is where the mini-mux goes to allow the board to "see" the upgraded RAM. Your "mux" board seems like over-kill for a simple 512k RAM upgrade. None of the RAM chips are piggy-baked, right? I wonder if this "industrial" board is designed to allow a RAM upgrade up to 4 MB? If there are no other sockets on the board to connect anything else, then it would rely on piggy-backing the RAM chips. I don't think you can just pull the board without replacing the F3 chip and expect the logic board to work, though. Washed it, eh? That one just doesn't sit well for me personally (how do you prevent corrosion)!
Anyway, every 128k/512k unit I've gotten, upgrades or originals have had one thing in common -- if it failed, it was always the analogue board, which was prone to failure, particularly the 128k boards that were upgraded with more RAM for which they were never intended to handle. But, you'll know for sure when you slide a known good logic board into the chassis and fire 'er up. On follow up, Larry Pina's excellent books on the subject only describe a checkerboard pattern with a logicboard issue and upgrades, but only 68000 processor clips. You don't have any wires between a C24 & R32 at D2 to E2 on your card do you? Check the programmer's switch at B1. See if pressing it resets the Mac or not. As I said, sometimes I would start up my 128k (orig. & 512k upgraded logicboard swapped in the same chassis) and I would get a checkerboard pattern that would only go away if I reset it. Sometimes, I would get it briefly on the way to the startup screen. Then, the other night, the flyback transformer died suddenly on me. I can't help but wonder if this problem was tied to its death. Larry Pina describes many such problems with various components on the analogue board. If it is on the logic board side, since it was reproducible on more than one of my boards, I would again have to say the problem originates on the analogue board, even if it has to do with getting the proper voltage to the logic board in order to return the proper video signal. I would very much like to a picture of this and yes, I will e-mail the digibarn pic and some other comparison boards, including my 128k to 512k upgrade. -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:compact.macs@mail.maclaunch.com> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com ---------------------------------------------------------------
