I have a Mac IIfx that I just recapped. I now turns on, but I get no chime/sound at all.
I tested the ROM SIMM and RAM simms in another Mac and it's fine.
Jump to content
Posted 13 February 2017 - 02:06 PM
Yes the speaker was connected. I am lucky enough to have another logic board. I replaced many logic chips and still no luck. I'm thinking the main 68030 CPU might be blown. It happened before on another Mac II. I played around with the scope, but it's a bit hard without the schematics.
I'll hunt for a new CPU.
Do you know if I should at least get the startup chime *without* the 68882 co-processor?
Also, to get it, I must have at least for banks of RAM filled. Is that right?
Posted 25 February 2017 - 11:39 PM
Ah, in my case it turned out to be the ROM. I tried a ROM-inator II from BMWOW and it's working now.
So now the question is: Is it possible to repair the bad ROM? How do I go about troubleshooting it? I don't see any replacement Mac IIfx ROMs available anywhere but I'm interested in restoring OEM parts as much as possible..
Posted 27 February 2017 - 01:16 AM
if the ROM is bad, then it COULD be suffering from bit-rot if it started life as a PROM so it works exactly like EPROM but with no window. So you burn it and its done.
if its mask-ROM its likely something different like failing buffer circuits etc internal to the IC.
Edited by techknight, 27 February 2017 - 01:20 AM.
Posted 27 February 2017 - 01:28 PM
I took a closer look at the Apple ROM SIMM and noticed the contacts were looking pretty dull. I wiped them down real good with some IPA and now it's working fine!
P.S. - A/UX doesn't boot with ROM-inator II
Edited by zuctronic, 27 February 2017 - 01:29 PM.
0 members, 0 guests, 0 anonymous users