I recently decided that I needed a new project to satisfy my inner tinkerer. I have never owned a Mac in Mac II form factor and thought I would give it a go. I was able to locate a reasonably priced Mac IIci and went for it. When I purchased the computer a could see some damage from a dreded leaking battery. The previous owner had cleaned up most of the carnage, but damage was done. I have recapped the entire board and repaired a few traces around power on circuit. However, the RTC is missing a couple of legs from corrosion. Is there a replace modern of this Apple custom RTC chip? Does any know a source for this chip? I have searched the internet and have come up short. I feel that if there is any hope to repair this Mac I am going to need that chip.
Mac IIci RTC 344S0042
- Thread starter Breezy
- Start date
Unobtanium part. Source: I tried to find some for my Quadra 700 repair project.
Functionally identical to the SE/30's RTC but in a different package... not all the PLCC legs are actually used.
There's a modern replacement for the SE/30's RTC... with some bodge wires or an adapter board it should work in place of the PLCC RTC.
Look at the bomarc IIcx or IIci schematics to get a pinout for it.
For what it's worth, the machine should work without that RTC (it's also the PRAM IC)... It just will be limited to floppy boot.
Functionally identical to the SE/30's RTC but in a different package... not all the PLCC legs are actually used.
There's a modern replacement for the SE/30's RTC... with some bodge wires or an adapter board it should work in place of the PLCC RTC.
Look at the bomarc IIcx or IIci schematics to get a pinout for it.
For what it's worth, the machine should work without that RTC (it's also the PRAM IC)... It just will be limited to floppy boot.
Correct, the RTC has been reverse engineered, but not made in the PLCC20 form factor...yet. It's not that difficult to do, it just needs VQFN parts and someone to do the PCB work for it - the code forthe MCU itself is done.
MCU being the ATtiny85? Implementing it by designing a PCB to convert the SMD package to plcc20? or are you thinking of an entirely different MCU?
Correct - you can get them in SOIC and TSSOP packages although to fit within a PLCC20 package size, the QFN20 might be best.
I have some MCUs on order I am going to work on a prototype. Hopefully with a little luck, I will be able to get something pretty special created.