Disk drive Issue - Advice/Where to start

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Disk drive Issue - Advice/Where to start

Hi everyone,

I have a pair of drives that had died back in '93 - first one drive stopped working and then the other not long after and that was the last time my //e saw any use.  I was at my parents' house this weekend and pulled the whole system out of the closet in hopes of trying to resurrect it.  When I attach either drive and power on the system, the drive spins but the drive head does not move to the outside position (and does not make the familiar clacking noise).  I can move the drive head when the drive doesn't have power.  When the drive has power, I cannot move the drive head.

Any thoughts on where to start to try to fix this?  I've done some Googling but am having a hard time finding someone with a similar issue.

 

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Clean Heads & Lubricate Rails

I assume you are referring to 5.25" drives being on a //e.

 

Good news is that this is *usually* a simple fix.

 

It will involve:

  1. disassembling the drive
  2. cleaning the heads
  3. cleaning/lubricating the metal rails that the drive head moves along

 

There is a video on YouTube showing the disassembly and head cleaning process. Just do a search for it - it's pretty easy to find.

 

Generally I use a cotton swap with a little isopropyl alcohol to clean the head and the rails, and then some silicon spray to lubricate the rails to ensure that the head can move freely. You should manually move the head along the rails after the cleaning/lubricating process to make sure that the head is capable of movement.

 

Let us know how you get on.

 

Cheers,

Mike

 

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Yes, 5.25" drives... I will

Yes, 5.25" drives... I will start with the clean and lube and let you know how it goes... thanks!

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If it is an electrical

If it is an electrical problem the most common failure in a Disk ][ drive is the 74LS125.  Luckily those are easy to change out as they are usually socketed and they are still readily available.

 

Worst case, floppy drives are cheap and plentiful.  You can find them used between $20-$50 all the time.

 

 

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Ok, both drives got a drive

Ok, both drives got a drive head clean and a clean and lube of the drive head rails.  Both now perform an inital "shimmy" on power up with the familiar clacking noise (although it's super quiet in one of the two).  Both drives spin but nothing else happens (unless I initially position the drive head to the outermost position before power up - then there's a nasty sounding noise after the "shimmy")

 

Any other thoughts?

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So I'm guessing you've tried

So I'm guessing you've tried booting a known good disk after head-cleaning the drives? It is normal for the drive 1 to keep spinning after turning the machine on if it can't find a disk to boot.

 

Which kind of 5.25" drives are they? The full height Disk ][ drives with the IDC-20 connector, or the later drives with the DB-19 connector?

 

When you say both drives spin, are you testing them individually - i.e. connect 1 to the interface card and test; then swap. Or are you saying with both drives connected they both spin up after turning on?

 

Do you have another interface card to test the drives with? It could be a dead OR failing IC on the interface card. Try lifting each chip up a small amount and then reseating them. This can remove any oxidation that may have formed on the legs of the chips. You can also spray a little IC cleaner into each chip socket for a more thorough clean.

 

Another common fault with the disk ][ drives can be caused if the IDC cable is inserted but off by 1 pin. It usually involves smoke and at least one dead chip inside the drive itself though.

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more details

Polymorph69 wrote:

So I'm guessing you've tried booting a known good disk after head-cleaning the drives? It is normal for the drive 1 to keep spinning after turning the machine on if it can't find a disk to boot.

Yes, but I'm not sure at this point if any of the media that I have is still good - it's all from ~1983-1992.  I tried several floppies with no difference in the results.   The drive head doesn't move after the initial shimmy - I thought it was supposed to do so to go to track 0.  I don't know the sequence of events from the drive perspective at powerup.

 

Polymorph69 wrote:

Which kind of 5.25" drives are they? The full height Disk ][ drives with the IDC-20 connector, or the later drives with the DB-19 connector?

 

I'm not sure now if they are 5.25" drives from a duodisk, the built-in drive from a //c, or an external //c drive.  I found the lower housing of the external //c drive, but the drives themselves have already been removed from whatever housings they were in.  My suspicion is that they're both actually //c drives.  Is there a way to determine what I might have?

 

Polymorph69 wrote:

When you say both drives spin, are you testing them individually - i.e. connect 1 to the interface card and test; then swap. Or are you saying with both drives connected they both spin up after turning on?

Yes, individually.

Polymorph69 wrote:

Do you have another interface card to test the drives with? It could be a dead OR failing IC on the interface card. Try lifting each chip up a small amount and then reseating them. This can remove any oxidation that may have formed on the legs of the chips. You can also spray a little IC cleaner into each chip socket for a more thorough clean.

 

Unfortunately I do not have a known good interface card.  I will certainly give it a visual inspection when I can.

 

Polymorph69 wrote:

Another common fault with the disk ][ drives can be caused if the IDC cable is inserted but off by 1 pin. It usually involves smoke and at least one dead chip inside the drive itself though.

 

I'll post a picture of the cable setup when I get a chance.  I suspect it is not the original ribbon cable from my DuoDisk and is related to the //c hardware.  I can also provide video of what's going on if it would be helpful.

 

 

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Yeah, I think pictures and/or

Yeah, I think pictures and/or video might be best to go any further.

 

If these drives are in such bad shape (i.e. no housing), you might be better off just buying a new drive? It might save you an awful lot of pain trying to diagnose the issue(s).

 

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Pics and vids

I still have the bottom plastic piece of an external //c 5.25" drive.  I'm guessing now based on some image googling that what I have are two //c drives, one that was the internal/comes-with-it, and one external.  Now I want to go back to my parents' house and search the barn for the DuoDisk...

 

Pics of drive and interface card (which looks pretty clean)

https://drive.google.com/open?id=1-YlKZ_pXzpvXbP3aix6ykNMT8I1Wt5-O

https://drive.google.com/open?id=1-PFC88PR4s7u4NQEyGxFBnbjWIcMGEPC

 

Video of boot with head starting at outermost position:

https://drive.google.com/open?id=1-hI9R0a-IfGNApxksARnyYbmHk4RYQOM

Video of boot with head not starting at outermost position:

https://drive.google.com/open?id=1-ZmE1k_1Q2mCuRnRwWCdj3afCwi2kMIj

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Some thoughts

You are right. According to your second video, the stepping motor doesn't work : at boot, the R/W head should go back to track 0, on the outer edge of the floppy disk . See this video for example.

On the controller board, you can try to swap the 74LS259 (ic labelled 9334 on you picture) who send the signals to move the R/W head to the analog board inside the Disk.

On the analog board, the ULN 2003 can also be the culprit.

I hope the stepping motor is fine.

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DougJoe wrote:Yes, but I'm

DougJoe wrote:
Yes, but I'm not sure at this point if any of the media that I have is still good - it's all from ~1983-1992.

 

FWIW, most of my 5.25 floppy media dates about the same, and 95% of it still works fine.  Even if you've got some bad sectors, it ought to be at least *trying* to boot and then failing to the machine language monitor or somesuch.

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It's *trying*

amauget wrote:

You are right. According to your second video, the stepping motor doesn't work : at boot, the R/W head should go back to track 0, on the outer edge of the floppy disk . See this video for example.

On the controller board, you can try to swap the 74LS259 (ic labelled 9334 on you picture) who send the signals to move the R/W head to the analog board inside the Disk.

On the analog board, the ULN 2003 can also be the culprit.

I hope the stepping motor is fine.

 

Thanks for the info, the video helped answer some questions.

The thing that I've noticed is that the stepper motor is *trying* to move the R/W head - I can see the pulley wheel move when the drive powers up (it's hard see in the videos I posted because the drive board is in the way).  If either of the chips you mentioned had issues, would the stepper motor move at all?

 

Also, I was able to get some interesting results (probably not a smart idea?) by very gently pushing the pulley wheel with a screwdriver at various times during the power up cycle - when the drive head wanted to move out at power up, pushing the right way seemed to help it along.  Same with pushing the other way when it was done trying to read track zero.  I even got a floppy to boot to a monitor prompt (i.e. this disk loaded some data but not all correctly).

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Lee Adamson wrote:DougJoe

Lee Adamson wrote:

DougJoe wrote:
Yes, but I'm not sure at this point if any of the media that I have is still good - it's all from ~1983-1992.

 

FWIW, most of my 5.25 floppy media dates about the same, and 95% of it still works fine.  Even if you've got some bad sectors, it ought to be at least *trying* to boot and then failing to the machine language monitor or somesuch.

Thanks.  I will continue to remain optimistic!  This was my system, oh, probably around 1988.

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