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1541 Disk Drive That Is Acting Demon-Possessed

C

Captain Midnight

Experienced Member
Joined
Mar 3, 2010
Messages
52
Ok, so I have an original 1541 hooked up to my 64C and after a day's testing/use where the drive appeared to normally function, it is doing all sorts of wacky things now. In specific, after turning on both the 64 and the drive, I will attempt to load up a disk. It will start loading the program and about 15 seconds in, the drive stops running and dies. So I restart the 64 and the disk drive. This time I go to load up the disk, nothing happens. So then I cycle power on the 1541 and all of a sudden the drive starts spinning, but will not seek a track. It just keep spinning, even after cycling power several times and unplugging the unit. After several such attempts, the drive starts up normally when the 64 does, but yet again, the drive doesn't respond to the load command and the process repeats itself.

To this point I have given the drive the compressed air treatment, both inside the drive and near/around the logic control areas to blow out # number of years' worth of dust and dirt. I have also checked the seating of all of the drive's control chips and everything seems to be fine there. I also thought that a belt might be an issue and/or that the heads had seized, but I don't see any missing belts and the head assembly appears to be intact and able to move freely back and forth. I've also checked the closing mechanism on the drive, but again nothing.

As an additional note, in some instances, if you are able to execute a load command, the drive will briefly try to seek and then the red indicator light will start flashing in a weird, random way (i.e. not the normal blinking "can't read your disk" way).

Here are my thoughts on possible issues/solutions. Please see if this sounds on the right track and/or if there's anything else that could be done. I should note as a caveat that I already have another 1541 on the way, as I am well aware of the fact that such drives had "issues":

--The drive is seriously out of alignment, which might explain this.

--One or more of the drive control chips has gone cuckoo.

If the latter is true, I have an unusable 64 with its 6510 intact. Could that be used in place of the 6502? I am going to try a couple of the simpler drive alignment solutions, but I fear a more complex alignment may be needed?
 
Since it reacts to your commands and sometimes even begins to seek, I would assume the 6502 is OK. Not sure about the 6522 VIA's. Perhaps a bit rot in the internal ROM's which causes the drive to misfire?
 
The 6502 and 6510 have slightly different pinouts, so they aren't interchangeable.

It's been years since I tried to fix a 1541, so I can't add anything else to what you said, but you are correct, 1541s were known to be temperamental. The later drives with a latch on them, rather than the earlier pull-down door, had a reputation for going out of alignment less often.
 
Hi.

I've seen this behaviour on a few drives - if it powers up fine and starts to load then the chances are the logic is all O.K.

I would check the 12v and 5v voltage rails as I have known the regulators to go nuts when they heat up.

Don't get the drive to do anything, just power it up and monitor the rails if you can, as the regulators will heat up anyway.

Let me know how you get on!

Cheers,

BigDaddyCainer.
 
Well considering the fact that I was able to acquire another 1541 for a decent amount, this one's going to the bone yard. I am pretty sure now that the issue is the stepper motor, which while I realize it could be replaced, I'm electing to just swap out drives and combine parts between the two drives, if needed, to make one good one.
 
Would you be willing to scavenge the circuit board? One of my 1541 boards is dead...it'd be a great help!

Kyle
 
I want to wait for the replacement drive to come in to see if I need to swap out any parts. Otherwise, you're more than welcome to whatever is left. Send me contact info and we can go from there.
 
Did you read the manual? There are many sources on the web for diagnosing common problems with the 1541, this is probably the most produced disk drive in history. There are many variables you've not taken into account such as whether your disks are good, and whether your C-64 works correctly. Did you clean the drive head? Before you start taking things apart start with the common problems.

Often if you format a disk drive you can get the thing back in shape, so you want to start there, after you have read the manual. Search the web for "drive knock" a BASIC program that you can load into your C-64 to wake up a disk drive.

From http://www.mofeel.net/666-comp-sys-cbm/3568.aspx
first pop out the disk and enter (WITH the drive door open):
open15,8,15,"i0":close15
(the above will make your drive knock the head back into what it thinks
is alignment)

bd
 
Yes I have read plenty of documentation on the 1541. I cleaned the heads, cleaned the circuit boards removing a layer of gook that was on them, cleaned the case, etc. I also cleaned the contacts on each of the microchips on the mainboard.

I tested several different disks, both old and newer. The same disk would work one minute and not the next, so disks aren't the incremental factor here.

The drive will one minute respond to load, open, close, etc. commands and the next hang the system. Then you flip the drive off and on and the head just keeps spinning meaning that the drive failed it's "POST."

I'll try this command, but I found another program that knocks the head backwards and the drive still responds in the above-mentioned flakey manner. I will tell you, though, that one of the power supply components on the mainboard, in my opinion, is running way to hot, along with the 6502 but that's not as surprising. But the power component is and I think that's a big problem. At this point, I suspect something with the PSU because the drive is just acting way too flakey for it to be much else.

All in all, again for the price I was able to get a replacement drive for, I'm going for it. I will make sure that drive is equally cleaned out, adjusted, etc. But I think this one has some issues.
 
Well today I got my replacement 1541. It's an Alps drive w/ the spring loader (I like the Newtronics version better myself), but it works pretty good. I just did a basic out of the box today and will probably inspect/clean up the inside over the weekend. It appears like it's alignment is pretty good, thought it might need a bit of reverse knocking. It sure as hell beats wacko drive.

By the way, if anyone wants to take their chances on said Satanic drive, let me know, and I'll be more than happy to pass it your way.
 
billdeg said:
From http://www.mofeel.net/666-comp-sys-cbm/3568.aspx
first pop out the disk and enter (WITH the drive door open):
open15,8,15,"i0":close15
(the above will make your drive knock the head back into what it thinks
is alignment)

bd
Click to expand...

Billdeg,

Thanks for the initialize command. I was lurking on this site and had a situation that called for exactly that. I dropped the front of my SX-64 on the counter (didn't lock the handle) and anytime you tried to load the directory of a disk, the computer would spew garbage characters to the screen. Tried to "load" a disk with the drive door open and got an error indication which narrowed the problem down to the drive itself. I executed the command you listed and "viola!" back in good order again.

Once again thanks,
Not-so-Angry White Guy
 
Hello,

I second what BigDaddyCainer says, i would check +12/+5V. Check the bridge rectifiers too.

Does the drive always work after cooling down/being powered off for a while ?

Regards
Jani
 
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