Need help getting a 400k floppy drive going mc 512k

[68kbits]

I recently acquired two Mac 512k with the original 400k floppy drives.

One of the machines had a jammed floppy drive so I did some searching and learned how to remove the crusty grease and lubricate the eject mechanism.

I have the eject mechanism moving freely, but I am unable to boot the machine from system 2.0 or 3.2 disks imaged onto 800k floppies.

I created images from multiple machines.

I even removed the 400k drive and put it in my plus to see if it would work in that machine.

It doesn't, I can not even format a disk.

I have the 400k in the plus, and boot the plus with system 2.0 in an 800k external.

I did clean the read head with a q tip and alcohol.

I also attempted to remove as much of the grease as possible from the ball screw that slides the read head.

I did not adjust any of the screws for head alignment or head height. Although this page suggests raising the read head:

http://lowendmac.com/tech/after.html

I read a few posts that also suggest demagnatizing the read head, but I haven't found a procedure or tried it.

What should I try next to get this drive working?

I am making some assumptions that may be false. First being that a Plus can use an internally connected 400k floppy, next that I didn't totally screw up the head alignment by cleaning the ball screw. I did move the ball screw manually before I thought about it being a bad idea.

The other 512 doesn't read either but I haven't attempted taking it apart yet.

 

[uniserver]

Sorry I was not more help to you buddy.

I'm really weird about my 400K external, or else i would let you borrow it.

Here is all I did to make a 400k bootable floppy used in my 512ke with my 400k external.

I went to this website earlymacintosh dot org. got the 3 images (System 2.0 Finder 4.1, released April 1985)

400k Write

400k Paint

400k System

I acquired these images with my powermac 7500

clicked on the image and disk copy opened up, showed it was a 400k image.

poped the 800k disk(s) in and it made the created and verified them.

then booted them up my 512ke /w the 400k external.

 

[uniserver]

ok just tried the whole process again with an 800k floppy disk... and I verify it does work. system 2.0 system disk boots from 400k external connected to the 512ke.

 

[68kbits]

Thanks, I'm still not having any luck.

I got the Paint and System 2.0 images to boot my mac plus with it's internal 800k and an external 800k from my IIGS.

Both disks in the internal 400k attached to the 512K will show a happy mac for a second or two, but then it goes to a floppy with an X and ejects the disk.

Does anyone know if a 400K floppy drove will work as an internal drive for a Macintosh Plus, or as an external in the IIGS case? (A9M0106)

If I put the 400K into my Mac Plus it will ask to initialize the disk, but then it fails almost immediately and ejects the disk.

 

[68kbits]

Well, I made some significant progress throughout the day.

I started working on my second 512K.

I started out by rigging a long thin Q-Tip contraption with a screwdriver handle to clean the read head without tearing apart the computer and the drive.

I made about six different boot disks. I had started with Sony brand 800K floppies, which were brand new made on my PPC 7200, none of them worked.

I then decided to try an image made on my SE/30, it worked. It was a different brand disk though, a no name.

I was able to boot all 4 disk images (3 different system 2.0 and 1 HD20 disk) on the second 512K after cleaning the head. It may have been the disks all along on that machine, so maybe the head didn't even need to be cleaned.

I then started back to the 1st 512K and none of the disks booted.

I noticed that the read head never seemed to move on the first 512K, so I decided to clean the head one last time. Still nothing, so in a last ditch effort I put the drive from the first machine into the second machine which was now booting.

Success, the drive worked fine in the second machine.

Obviously there is something wrong with the first 512K

What would cause the read head to fail to seek in the first machine? I am assuming it is a bad chip or connection, or could it be the power supply?

 

[68kbits]

Well, I don't have a great explanaintion for this, but now they are both working!

I took the logic board out of the 1st one, looked it over, blew off just a little bit of dust, put it back in and it started seeking immediately.

The screen was blank, so I moved the connector ever so slightly and it came on with the desktop image.

I am assuming I must have reseated a connection that wasn't working, unless it really as the dust.

The frst drive obviously needed a once over since it was jammed, but I think my primary issue was the Sony disks.

These 400K drives must be a lot pickier than the 800K. These same Sony disks are no issue in my other machines.

:b&w:

 

[markyb86]

Might be a crack in one of the lines in the floppy cable. Used to have a problem like this with an external cd rom case. Switched the cable and all was good.

 

[68kbits]

That's a good point. I will have to double check the floppy cable.

I am pretty confident the connector on the analog board needs to be resoldered though. Jiggling that cable seems to have an impact.