# LC520 won't start (boot)



## eddie32818 (Oct 29, 2004)

Hello,

I've been trying to fix a friend of mine's Mac LC 520. It's very old (1993) and she said one day it stopped powering up. (no sound, no display) I have a good understanding of PC's (windows) but I haven't much experience with Apple-Macintosh machines. That being said, I hope someone can please help me figure out how to revive this LC 520.

I took out the logic board and replaced the 3.6v lithium battery (the old one was at .5v) and it still would not boot up. When I first tried to power it up, I heard a brief hum (1 sec) but no other sounds; also the fan doesn't spin. 

I tried the keyboard On-OFF power button, Command-Power combination, and the Contol-Command-Power combination, which none worked. (I had the main switch set to "1" for On, out in back  )

My first suspicion is that the problem lies with the psu (power suppy unit) and I wanted to know if there was any other test or task I can do to revive the machine. 

If it is the power suppy, Is it possible to get a replacement psu for this "all-in-one" mac? 

Thanks for taking the time to help me with this.

Eddie


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## eddie32818 (Oct 29, 2004)

I did a little "googling" and I saw that there is an "analog board" that is in the machine. Does this have the power suppy buitlt into it? Please tell me if it can be replaced or if it has serviceable parts that can be replaced. Thanks.


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## DoorGah (May 14, 2005)

Hello, First of all if you get into the covered, upper case it gets dangerous. It stores a charge in there that can do you dead. The analog board is possibly bad and this is Not light duty.

When you replaced the battery did you wait 5 minutes or so before putting in battery? You may have a trapped signal. Do this... pull the battery (computer unplugged) slide the logic board back in. push the keyboard power up button. If you are not sure switch is in "on" position in back, try it both ways. This may release (drain) signal. Wait a few more minutes, put battery in correctly-) and try again. 
If video or other components are bad, it will maybe hum or grunt but that's it. The analog board is more often what dies before logic board. 
You might reseat the RAM while LB is out. Does not sound like RAM issue however.

Let me know what it does after redo.


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## eddie32818 (Oct 29, 2004)

Thanks for replying. Also, thanks for the high-voltage warning.

I tried your intructions and this time I got the ps to whir-up (fan is now spinning) and got a steady green LED in front. Making progress, but unfortunately, the display is blank and no other sounds (not even a spinning hard drive) can be heard.

What should we try next or is this machine toast?

Eddie


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## DoorGah (May 14, 2005)

Well Eddie, It doesn't sound good.
Try this and post. Remove anything attached: ext. drives, printers etc.
Unhook keyboard and mouse, plug mouse directly into computerno keyboard. Try it...
If no better... unhook hard drive cables. try it...
dp


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## eddie32818 (Oct 29, 2004)

Well I tried several things this weekend: I tried your suggestions of no peripherals, no keyboard, but mouse directly into the machine. This didn't work at all as the machine won't start with the main switch thrown in back because (as I understand) you need to press the Power Button on the keyboard for it to work at all. 

I ended up removing all these components, one at a time, to see if it was preventing the boot up process. These included the RAM sticks, the hard drive, the floppy drive and the CD-ROM drive. Still kept getting the power supply hum with the spinning fan and the green LED indicator light on in front.

Following the reasoning of the "process of elimination," I'm beginning to think it's either the crt, the logic board or the analog board. I wish I had another (working) identical machine that I could swap stuff out and check for problems. 

Can you think of anything else we can try?


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## DoorGah (May 14, 2005)

Prayer is the answer... If it were a new computer the analog board would be what was swapped first. CRT's usually the last. Duh, on forgetting the KB/switch thing.
I can't imagine this helping. It's called zapping the P- RAM. At start up, after start up sound or 1 second delay, hold down these four keys... Command, Option and the letters P and R. Keep holdin all 4 until you hear it restart or flash 3 times. Let go. If that doesn't do it, you did all you could. Apple needs good techs. You should check into it if of interest.


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## eddie32818 (Oct 29, 2004)

I tried the P-RAM zapping thing with no success. 

Given the age of this machine, I kind of felt I was beating the proverbial dead horse...I knew early on that parts for ancient equipment are hard to come by. Come to think of it, I even tried to clean off some of the logic board (alcohol) that had a few leaky electrolytic capacitors and the old battery leaked some, too.  

I enjoyed tinkering around with this project, as all problem solvers do, I suppose and I think I'll have a better "heads up" on the next time I work on an old Mac. I'll tell my friend to pitch it back in the closet, until we can maybe find another one to cannibalize parts from it.

Well thanks for all your help and keep up the good work at this site!

Ed


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## emoxley (Jan 6, 2004)

One last ditch thing to try..............
This probably won't do any good either, but worth a try. You never know.
Have you tried holding down the Shift key, while booting up? That will make it boot up (IF it will boot up) with extensions off. If it boots up that way, that means there's a conflict with an extension. While up and running, run Disk First Aid (found in System Folder, in Utilities folder).

Again, if it gets this far, it might not hurt to do a "Clean Install", or an "Initialize & Install", if your friend has the system "Restore" disc.
A "Clean Install" will install a new System Folder, with all new extensions and preferences. An "Initialize & Install", will wipe the HD clean, and reinstall EVERYTHING back on it, like it was when it was brand new. The latter should definately take care of the problem.
Good luck!


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## eddie32818 (Oct 29, 2004)

Thanks for your suggestion Emoxley, but unfortunately it didn't work for me. 

I am grateful for all the help I got from this forum and I hope these posts will help others too.

Thanks and keep up the good work. :up: 

Ed


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## DoorGah (May 14, 2005)

Sorry it didn't help, maybe next time. It sounds from your description the unit was stored in a damp basement or? I've seen a lot of older Macs (even Apples) that didn't look as described.Tell your friend not to pour water in them when mad...-)
Good Luck.
doug


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## emoxley (Jan 6, 2004)

It's such an old computer, that it's not worth putting money into. If you can get another one for free, or almost free, it might be worth the time to work on it. Or it might not. You can check at Goodwill Thrift Stores, or Salvation Army Thrift Stores, or Mission Stores, and possibly turn something up. Could run ad in paper, asking for that model...........
Good luck!


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