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Mac 128k - Black screen when floppy inserted

gubbish

Well-known member
Hi everyone,

Looking for some help in recovering from a less-than-brilliant move on my part.

I recently came across a Mac 128k for sale in my area, and quickly scooped it up.

When testing it out for the first time, all seemed normal. Plugged in, turned on, and the disk icon showed up on the screen.

When I attempted to insert a disk into the internal drive(system 2 400k floppy), I found that the disk was physically blocked about halfway in. I assumed that the drive mechanism must be at least partially stuck, so I turned it off, connected a 400k external drive that I already had, and using that I was able to boot into system 2.

Later, I tried booting again (from the external drive) and behavior was flaky - first it gave me a few "0F0064" errors, but after trying again later it booted into system 2 again.

And finally, in an admittedly ill-advised move, I tried putting my "Paint" disk into the internal drive to see if it would go in. Instead of going in, it got stuck in the drive halfway, and when I was removing the disk suddenly the screen went black. xx(

After smacking myself, I tried turning it on again a few times. It still makes the "bong" sound and seems to be booting from the external drive, but the screen is completely dark. Sometimes I see a faint flicker of light when the mac is first turned on, and there are some seemingly random white blobs that flash on for a moment when it is turned off.

If anyone can point me in the right direction on this one, I would be very grateful. I'm not sure if I shorted something, blew a fuse or a cap.. I'll have to get a torx tool and open this machine up, but I'm not quite sure where I should start looking. Any help appreciated, thanks!

 

gubbish

Well-known member
Thanks!

Ordered a Torx screwdriver yesterday and it should arrive in a few days.

Will keep you apprised of my progress.

Am I correct in thinking that the logic board is probably ok, and that the problem most likely lies with the analog board?

From other posts on this forum, I gather that a Mac Plus analog board would work in a 128k. I do have a Plus in working order so perhaps I could try swapping its analog board in this machine to see if that would work.

Now I just need to find room in my apartment to work on this.. :?:

 

techknight

Well-known member
it would probably be easier to just swap logic boards between plus and 128k to rule out the logic board.

 

gubbish

Well-known member
Thanks, I'll try that!

The torx tool should be arriving tomorrow, so I'll proceed with caution.

Will let you know how it goes.

 
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