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Floppy drive on Atari 1040 STF broken?

A

Aposke

Member
Joined
Apr 25, 2008
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24
Hello there fellow collectors,

I recently bought an Atari 1040 STF at a flea market in my town, it came with cables and everything and was said to be in a good working condition.
Now I have hooked it up at my home only to find out that every time I try to access a floppy disk through the internal floppy drive, it gives me the error:
"Floppy drive A: doesn't respond..." and so on.
I tried out a game disk, as well as the standart TOS-Installing Disk, both give me the same error.

Does anyone have an idea what could cause this problem or is the floppy drive simply broken?

Thanks in advance,
Alex
 
Some additional symptoms would be helpful. Does the drive spin when you access it? Have you opened up the case and checked to see if the connectors are still attached to the drive?
 
Oh yes, I forgot to mention that the drive does spin when you try to access it.
All connectors are still there and properly attached.
The reading head is also intact, and the small LED at the top of the keyboard also lights up when I try to access the drive.
 
Hmmm...

I've never had one of those Atari drives apart, but on typical 3.5" floppies you have 2 to 3 micro switches at the very front of the drive for:

  • Disk Insertion
  • Write Protect
  • Density

The Density was to tell between 720k and 1.44Mb floppies.

Check the disk insertion switch. It's probably bad.

Now, how can you tell which is which? Look to see where the switches touch the disks. That makes it easy to tell.

RJ
 
I don't know if this is remotely similar, but I'll mention it anyway...

I've just had a Sony MPF520 drive in bits to solve a similar issue -- the disc felt like it was mounting correctly, but the INDEX and READ_DATA signals were dead (floating high). Interestingly the drive still honoured Drive Select (DS0 in this case) but ignored MOTEN (Motor Enable).
If you pushed the disc in just the right way, it was possible to get the disc to mount and the signalling to go active.

The problem with this drive was that the disc-detect switch was utterly gummed up with oil, goo and other unmentionables, and the mechanism was gummed up with dusty old grease (interestingly the head lubrication was OK, but the runners that supported the disc tray were basically glued).

Took me 10 minutes of disassembly, 20 of reassembly, multiple lacerations and some 3-in-1 oil to get that stupid thing working again. I wouldn't advise it -- it's a total pig to get the top part of the disc tray back into place. You basically have to put the shutter-opener in, then the spring, then install the lower tray, then put the upper tray in on top. It took me half a dozen attempts -- usually two or three of the mounting pins will seat, but one will sit stubbornly on top of the runner.

All this because I was too lazy to pull the logic analyser off the top of the storage box in the cupboard and get another drive :)
Truth be told, though, I do have another drive within fairly easy reach -- a Citizen "something-or-other" that's NIB. Problem is it's rigged to run in a PC (Drive Select 0 and Automatic Density Selection with READY output disabled) and there are no visible config jumpers on the board :(
 
If you have an external drive available to plug into the system, there's a jumper on the main board to treat the external as if it was the internal. This might help in troubleshooting.

Otherwise, the internal drive takes a standard 34 pin (at least according to the schematics) floppy connector. You can try a plain old 1.44MB drive in place of it; just be sure to set it for DS0, not DS1.
 
Thanks for your advice so far, I'm gonna try out everything you recommended tomorrow.
I'm gonna tell you if something worked.
@Chuck:
I already tried connecting a 1.44Mb drive to the 1040STF, the computer booted, but when I tried to access the drive, it didn't react at all, no matter if it was set for DS0 or DS1...
 
Aposke said:
@Chuck:
I already tried connecting a 1.44Mb drive to the 1040STF, the computer booted, but when I tried to access the drive, it didn't react at all, no matter if it was set for DS0 or DS1...
Click to expand...

Hmm, I'm working from the schematic and the connection at J10 and the power connector at J9 look absolutely vanilla plain DS0 (i.e. select on pin 10, motor on pin 16).

If you have an external drive, you can force it to be drive 0 by setting jumper W2 to 1-2 (should be set to 2-3).
 
channelmaniac said:
Hmmm...

I've never had one of those Atari drives apart, but on typical 3.5" floppies you have 2 to 3 micro switches at the very front of the drive for:

  • Disk Insertion
  • Write Protect
  • Density

The Density was to tell between 720k and 1.44Mb floppies.

Check the disk insertion switch. It's probably bad.

Now, how can you tell which is which? Look to see where the switches touch the disks. That makes it easy to tell.

RJ
Click to expand...

So, today I opened the Atari floppy drive (an EPSON MD-480L) and checked for any switches at it's front.
As far as I could see, there were none. Maybe I'm just not seeing them, but there IS a cluster of 3 open connector "holes" (don't know the english word)
labled DF1, DF2 and GD.

@Chuck: Sadly, I don't own an external drive yet, but I'm searching for one on ebay already.

Thanks for all your help so far!
 
channelmaniac said:
Those 2 blue things on the right side of the pic are the plungers for the microswitches.

RJ
Click to expand...

Okay, I checked both of them and the one in the front is the write protection switch, so I guess the one in the back is the disk insertion switch.
The weird thing about this switch is that it still gives me the error message, even if I hold it down manually while checking for a disk...
 
A test with a new drive...

A test with a new drive...

So yesterday I got a new internal floppy drive for the 1040STF by my Uncle, which worked just fine with his Mega ST.

I installed it into the 1040STF, booted it up, and tried to access the disk drive.
It gave me the same error again. Then I tried it with an external Atari SF354 (yes, I used a single sided floppy) and again - it gives me the same error. Worse yet, the drive won't stop trying to read the floppy, even when I've taken it out already!
The thing is that the SF354 works just fine on the Mega ST of my uncle too...

The only reason I see for this is that the IDE controller is somehow broken.
Or is there maybe another reason for this?

Thanks in advance,
Alex
 
But... make sure the internal cable is seated properly on the drive. If it's off by a set of pins or installed upside down you'll have odd problems on the drive bus.
 
The FDC IC looks okay, but I can't really examine it much better than that, I also cleaned the contacts, but that didn't do anything.

@Channelmaniac: Yes, the internal cable is seated correctly.

If the only solution to this is buying a new FDC and soldering it onto the mainboard, I'll just rather give up on this one.

Edit: Okay, now this is weird: I just noticed that the SF354 also starts trying to read a floppy even if the Atari is turned OFF, however if in this state i pull the floppy cable, it stops spinning immediately.
 
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Chuck(G) said:
Okay, either you've got the drive cable upside-down or a row offset, or that U305 (7406) is bad.
Click to expand...

What do you mean by U305?

Edit: Sorry, but I made a false statement above:
The external drive does NOT try to read a floppy even if the Atari is turned off, however if the Atari is turned on and you pull the connection cable while the external drive tries to read the floppy, it stops.

Edit2: It also doesn't seem to matter if the connection cable is in the "in" or "out" box of the external drive.
 
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