Q: What sort of hard disc was in the Mac LC?

The LC has a SCSI hard drive. There were some USB-to-SCSI adapters earlier, but even if you could find one, I doubt that it would be useful in connection with a modern Mac.

http://support.apple.com/kb/SP205

USB adapters/enclosures for ATA/IDE hard drives can be used with modern computers, but that does not help you in this case.

A bad logic board battery can sometimes cause unexpected problems. The LC has a 3.6 V battery. You may want to check whether it has been leaking, and thus perhaps damaged other components. Also, old leaking/bulging electrolytic capacitors can cause difficulties.

Have you tried starting from a tools floppy?

Have you tried a PRAM reset?

http://support.apple.com/kb/ht1379

Does the computer react at all? Any sounds? Anything (messages or icons) on the screen?

Jan

There are adapters. You could perhaps find something like this:

http://www.belkin.com/support/dl/f3h1381revised.pdf

Also, you may want to take a look at the following document. However, a plain LC is not mentioned, and I do not know whether a low battery voltage would affect the video output at all in this computer.

http://support.apple.com/kb/ta35928

Jan

If a bad internal battery on the motherboard were the culprit, you'd still have a spinning hard drive - although a hard drive that has sat for years could be unable to spin because of an electronic/mechanical malfunction.  The cooling fan should spin, but they're inexpensive and wear out, often requiring replacement.  When an inadequate magnetic field is all that's created, the fan shaft won't spin, sometimes causing the fan blades to twitch slightly or do nothing.  Although the hum may sound as if it's coming from the fan, it may actually be a failed power supply.  You might try to find another LC (LC, LC II, LC III) or any other SCSI-based Mac, into which you could install the LC's hard drive.  Considering that the original hard drives were 40 or 80 MBs, the number of files to be retrieved from it would be reason to spend as little as possible, to accomplish the task.

A little review of the startup sequence might be helpful.

The computer polls the devices connected to the motherboard to see what is there.  If it sees a system disk in the floppy drive, it will boot from that first.  If it sees a system disk on the hard drive it will start from that.  If it does not find a system folder it will show a question mark.  If you are not getting a question mark on the sreen, you have more serious issues. 

If you lift the cover off the compter, you can listen to hear if the hard drive spins up.  If it does not spin up, you can drop the handle end of a screw driver on the round foil sticker that covers the center screw for the hard drive platters.  That may jar the platters and get some old lubricant to break loose.  This is a last ditch effort to get the platters spinning.  Use as a last resort. 

The best thing to do before suspecting stuck platters is to test the drive bysticking the drive in another computer.  You can connect just the four wire power plug and turn the second computer on.

Lack of start up chimes is also not a sign of death.

Personally, I would take every connection apart and reconnect everything.  You may just have a bad connection that need the cleaning that occurs when disconnecting and reconnecting.  That goes for removing and reseating thejRAM, too.  Good luck.