Interesting Classic problem- bad logic board?

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Interesting Classic problem- bad logic board?

I've never used a mac before, so i don't know much about these, so appologies for my ineptitude.

About a year ago i picked up a Mac Classic (w/HD) out of somebody's trash heap. Took it home plugged it in,flipped the switch got a startup bong and a disk with a flashing question mark in place of the smile mac. I searched the internet for help, all i got was something about dead ram.

Now i'm really determined to get this thing working, so here's the deal

The disk thing happens, and the mouse doesn't always work (sometimes after several restarts it will) SOmetimes the hard drive spins up then spins down strangly like the motor is choking...., sometimes spins up and stays, or doesn't spin up at all. Sometimes it won't let me boot from rom, but when it does, it throws me error 02. The superdrive doesn't seem to work (the mouse button on startup eject thing won't work)

Today i did some fancy key work and got the finder to start from ROM. No mose so i had to use the keyboard, and some keystroke in th system folder brought up the properties.

Interesting: The created date matches the manufacture dat (i think) but it said iw was last modified January First 1904 (no Y2K compliance here!) But how the heck could the ROM be modified? Unless someone dumped the ROM, edited it, and burned it to a new one? This thing came from a low budget apt. bldg in a bad neigborhood, so i doubt that.

I have no way to discharge the monitor (working on that, but 1500 volts is not something i feel like dealing with)I'm flat broke so a professional discharge/repair is not an option.

So am i looking at a a bad logic board here or something as somple as cleaning the ROM connector?

coius's picture
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If the HD is dead

it can cause those problems. especially if it is sending the wrong data. I have had the same problems with dead drives in both PC and Macintosh machines. Even the recent iBook Dual USB 900MHz G3

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Is unplugging the HD soposed to improve this, or no?

I uplugged the SCSI connector from the HD, didn't change anything

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Suggestions

First off I'm betting the PRAM battery is dead. There's a little battery on that logic board that keeps track of where the computer is to boot from, the date, and a bunch of other settings. If it's dead, the date will default to 1904... and i know that some older Mac models will refuse to even budge without a good stout battery in them. (1904 is what the Classic is set up to default to; by no means does it mean its not Y2K compliant. Macs are and always have been the way i remember it, up to like 24,XXX or something to that effect?)

The HD going up and down could just as easily be the fact that it doesnt see a System Folder (read:an OS) on the hard drive. It will spin it up, look for one, see that there isnt one, and then say "Well I need one and its not here" and then spin the drive back down again.

So first, if youre really looking to get the little bugger up and running, i would take that battery out and start hunting for it. If youve got a good Radio Shack or other electronics joint in the area, they will probably either have or can get the equivelent.

You're right about the voltages; just don't. I know there are a few people out there that would disagree with me, but I'm not dead and quite happy about it because I go that route... let them take the risk.

My Classic memories are fuzzy... does it have a slide out/pop out tray/etc that the motherboard/logicboard rests on? If so quite a lot of this stuff could be done without getting anywhere near the CRT/transformer. (From memory it seems like the logic board is on "rails" and slides out...)

The bomb booting from ROM is sort of a bad sign... could indicate that all this wouldnt be worth it and that the logic board might indeed be faulty. But it's not a definite though; so its your call at this point.

-- Macinjosh

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Well, i'm getting 3.5~3.6V on

Well, i'm getting 3.5~3.6V on the battery. I tried booting it from the floppy by removing the HD and RAM expansion card. Didn't work. I've got a Beige G3 that i can work on once i get a monitor, but this one kinda had appeal to me.

Maybe i'll try hooking up the Superdrive from the G3, maybe the classic's is just dead. maybe a relative will be getting a Macquarium next year.

On a side note, are there any other compact mac's motherboards that would work in this (maybe a classic 2?)

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Could be the mobo.

Actually, it could also be a problem with the main board. Otherwise, have you checked the jumper on the expansion card? There is a small jumper on it, right besides the soldered RAM. If it's set to "NO DIMMS" that could also be the problem.

Cheers...

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