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This disk is killing my 400k drives!

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Having some 400k drive issues and hoping a resident expert here can help ...

 

A few weeks back I got out a classic old Mac boxed game (Dark Castle, if you’re wondering) and decided to play it from the disk on my 512k.  Annoyingly, the disk wouldn’t read, and suddenly neither would any other disk, so I took a look at the disk - the disk medium looked 100% fine.  I decided the 400k drive head must be dirty, opened up the 512k and thoroughly cleaned the head with isopropyl alcohol.  Still won’t work or recognize any disk at all (attached video shows what it does when I insert any disk on startup), and will fail to initialize anything inserted.  Now I make a mistake and decide, somewhat stupidly, that the disk is probably fine and I just had a weird sudden drive failure ... so I try the same disk in an external 400k drive.  All the same things happen.  Suddenly I’m worried I’ve ruined two of my drives with this bad disk!  Again, cleaning the drive doesn’t help.  So I open up the Dead Mac Scrolls and google around for help — I see various mentions of a “track zero alignment procedure” (the Dead Mac Scrolls, p. 274, says if you can’t even initialize a disk, it’s not a stepper motor misalignment but possibly a track zero sensor misalignment) but no good photos or specific instructions for a 400k drive (the Dead Mac Scrolls diagrams are for an 800k drive only, I think).  But anyway - how would I very suddenly experience track zero sensor misalignment only after using this particular disk?

 

By the way, I did something risky and tried the same disk again in a disused 800k drive I had lying around ... it also failed to read, and AGAIN the next disk I inserted couldn’t be read either ... however, in my 800k drive, running a normal cleaning disk with alcohol through the drive a couple times got everything back to normal and it’s now 100% fine.  Again, though, head cleaning didn’t help my 400k drives at all.

 

So - here are my questions:

 

1.  What the heck could possibly be wrong with this disk that it can ruin any 400k drive it touches (but again, looks entirely OK - it’s not like it’s shedding dust or the disk medium is visibly scratched or anything)

2.  What’s the proper and official way to clean the head of my 400k drives?  Since head cleaning fixed my 800k drive, I’d think that cleaning the 400k drive heads should work, but it doesn’t seem to ... do I need to do anything other than wipe the little white shiny head guy with alcohol?

3.  Is there anything else I should try, like this track zero sensor alignment procedure?  Is there a clear set of instructions for that somewhere, specific to a 400k drive?

 

Thanks for any help!

 

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I’m really doubting the drives are dead. Obviously there is a LOT of something built up on the disk, even if you can’t see it.

 

Cleaning diskettes are a lot more abrasive than a cotton swab, so it would be nice if you had a single-side cleaning disk. 
 

One thing you could probably try is, with the drive open, hold the spring-loaded pressure pad up with your finger and insert a standard cleaning diskette with some alcohol on it. This way you won’t rip the felt pad off from it getting caught on the cleaning disk.

 

I’m betting it’s a thick layer of grime. Had it happen on old PCs many times. Insert an unknown disk and all of the sudden it won’t read anything. 

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Don't use cleaning disks on 400k or other single-sided drives or you'll damage/dislodge the pressure pad and render the drive unusable. The pressure pad is a little felt pad that, on the 400k Sony drives, is on the arm on the top of the drive directly above the head. This pad presses down on the disk surface to ensure full contact with the head. If this pad is missing, it will not generate enough pressure to properly read the disk and may scrape up the top of the disk causing a lot of debris to be generated. Cleaning these drives requires disassembly and manual cleaning of the head with a lint-free swab and special cleaning fluid, but you can get away with carefully using a cotton swab and 90% iso alcohol. 70% iso also works in a pinch. You'll also want to check that the pressure pad is still properly attached. If it isn't it may be in the drive somewhere.

 

Even though your disk media may not look bad, it may be heavily shedding particles and/or binder material all over the heads of your drives. I probably wouldn't try using it again.

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Yes, you should never just stick a regular cleaning disk in a single-sided drive. However, like I said, you could, with the drive out of the machine, put the cleaning disk in and hold the pressure pad assembly off of the disk with your finger. I don’t think it would hurt anything that way.

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Yes. Originally it came on two 400k disks. Later it was shipped on a single 800k disk. I prefer the full-on classic experience complete with grinding 400k disk drives when you reach a new room, naturally ...  
 

“Nya nya nya nya nya”. Greatest game ever 

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Thanks guys, there was some good advice in here.  I found a proper 400k drive cleaning kit on eBay and the external floppy worked immediately fine after one run of the cleaning disk.  Great!  

 

My internal drive is another story ... it’s definitely wonky.  Cleaning didn’t help.  After adjusting the track 00 sensor, I was able to get it to initialize disks again, and it can read/write disks fine as long as it initialized them itself ... but it can’t read any disk initialized on any other drive.  Pina suggests that means I need to adjust the stator, but my efforts there have been utterly fruitless so far.  Other advice welcome, otherwise I may use this one for parts ...

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