5 Replies Latest reply: Dec 19, 2012 12:14 AM by Dougal222
Dougal222 Level 1 (0 points)

Hi, Can anyone help me with problem with my classic Macintosh LC III please ?


It worked fine when i bought it about a year ago but the started giving the dreaded booting problem due to a failed battery. At some point I decided to re-seat the ROMS (there are two - Hi & Lo) by removing them and re-inserting them into the sockets.


The sockets have two extra connectors making them longer then the ROM chips. I stupidly inserted the ROMS badly, instead of closest to the expansion bay i inserted them closest to the other side.

The ROMS got really hot to touch and i switched the LC III off and put them in properly.

Since then I have TWO problems:


A: With the FPU in place, when I switch the Mac on i get No display and no sounds... Nothing.


B: Without the FPU I still get No display and No chime sound but i DO get the sound from the speaker which it used to make just before the chime.


I have since replaced the battery with a brand new one, but I am still having these problems. I am suspecting that the FPU is probably damaged and so are the ROMS.


I have tried resetting the PRAM by holding down the appropriate keys but have had no luck.


Is there anything else I can try ?


If there is nothing else I can try would anyone know where I can get a set of ROMS or maybe somebody who can reprogramm a new set of ROMS for me ? Since i own the original ROMS and Apple no longer supports the machine would it be legal to have a new set reprogrammed ?


Any help will be greatly appreciated.



  • Jeff Level 6 (11,477 points)

    In 13 years of reading/posting in these Forums, I've never come across a suggestion (or made one) to remove the ROM chips, as a means of troubleshooting startup problems.  A new battery should have cured the problem, if not a PRAM zapping.  I doubt you'd find anyone with the hardware needed to program a set of ROM chips.  I'd suggest checking eBay for an LCIII motherboard, because I think it would be unlikely to find an auction for the ROM chips alone.  I own an LC I and LC III.  A couple of years after buying the LC III, I bought a spare motherboard for it at eBay, in the event of failure.

  • Dougal222 Level 1 (0 points)

    Ok... Its not the ROMS as i replaced them and the problem persists.


    I noticed the 68030 CPU seems to get hot quickly as does the chip in the middle of the logic board.

  • Dougal222 Level 1 (0 points)

    I'm still trying to save this Macintosh. I have replaced the ROMS and the PRAM battery but still does not work.


    The computer powers on and it does a small sound from the speaker but no bong. The HD starts up and the fans work. The screen remains black, no startup bong/chime.


    I have tried resetting the PRAM and leaving it on all night. I tried switching on/off quickly. Nothing.


    I tested the voltages from the PSU. The 12V line gives 11.8 and the 5V gives like 4.9. That should be ok no ?


    I tried disconnecting the floppy drive and the HD and i have tried cleaning the motherboard with a proper PCB cleaner spray.


    Is the Logic board trash ?

  • paulpen Level 1 (30 points)

    "The ROMS got really hot to touch"


    And you say other chips are getting hot too. If you're *sure* the ROMs (and everything else, e.g. RAM) are now inserted properly and that you have a good battery installed, then the motherboard may be fried. But to be 100% sure, you need a second LC III so you can swap parts, e.g. ROMs, power supplies, etc., to do further testing. It could just be the ROMs.

  • Dougal222 Level 1 (0 points)

    Nope... I tried replacing the ROMS and same results.