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5.25" FDD 360 kB - reading ok, problems writing and formatting

G

giobbi

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Hi all,

I have a Chinon FZ-502, 5.25" FDD unit, 360 kb (afaik). I used it to build an external unit for two portable PCs (you can read about it in this thread:
http://www.vintage-computer.com/vcf...-FDD-out-of-an-internal-one-(is-it-possible-) )

I discovered this drive can read perfectly the disks made by another PC (I used both xcopy /v and fc /b /v commands to compare source and target) and, also, it seems to be aligned: I used the alignment test from the "Image Disk" software.

When I try to write a file on it, i got a "general failure" or "data writing failure" error.

Formatting, it returns a lot of bad sector (I formatted with Format Master with the verify=on option). The floppy disk itself is ok (I tried many of them: they can be formatted without problem by my XT clone).

Of course I already cleaned the headers and I tried with two different cables (both tested and known to be good, though).

I tried to set the TERM jumper open or closed (yes I know it can't be the problem, but...)

Any idea?
 
Just googling some Russian for jumper settings on drive:

MS2 should be closed and MS1 open for 300rpm
DC-RY closed
TM closed
DS0 closed (drive select which you must have set correctly, anyway for twisted cable)
TERM = termination, which you tried

Hope this helps,

Larry G
 
Try this floppy drive in a different computer or at least with a different controller and see if there's any difference.
 
retrogear said:
Just googling some Russian for jumper settings on drive:

MS2 should be closed and MS1 open for 300rpm
DC-RY closed
TM closed
DS0 closed (drive select which you must have set correctly, anyway for twisted cable)
TERM = termination, which you tried

Hope this helps,

Larry G
Click to expand...


The only jumpers on the FDD board are TERM and DS0, 1, 2, 3. Did you find a site talking about this same drive (Chinon FZ-502) ? Can you kindly pass me the link?
 
My first checks would be cleaning the interface connector plus using another cable (connectivity issue? controller as Stone mentioned?), and cleaning the heads once more (I've had on more than one occasion, drives which failed to write 90% of the time, purely because they were dirty - despite having a 100% read success).

Just my two cents.
 
Stone said:
Try this floppy drive in a different computer or at least with a different controller and see if there's any difference.
Click to expand...

I tried with another PC (unfortunately running WinMe) and the result is worse. I will try to check it with another PC, I should have one running Win98 somewhere; at least I can boot in pure ms-dos...

However I got some more info. I took again the Bondwell 8088 laptop and connected the drive as external one.

It formats the disk, but only at 180 kB -179.712 bytes free- invoking only the head 0 and never the head 1 , so I suppose it's assuming it's a single side drive.

I can't get the rid of the format command (DOS 3.21), no way to make it to format double sides.
Even the use of drivparm (DRIVPARM D:2 /F:0 /H:2 /S:9 /T:40 -> it's the C: drive in this case) doesn't help.

The good news is the drive works fine (writing).... I believe there's some hidden jumper on the board telling it's a single side drive. Maybe somebody modified it to be used in Commodore environment or something similar...?
 
MS DOS determines if a drive is single sided during a format because it fails to write data on head #2.
I'd say head 1 has cleaned up and head 2 is still a tiny bit too dirty to perform a good write - at first guess.
 
SpidersWeb said:
MS DOS determines if a drive is single sided during a format because it fails to write data on head #2.
I'd say head 1 has cleaned up and head 2 is still a tiny bit too dirty to perform a good write - at first guess.
Click to expand...

I tried to clean them again, no changes :-( [btw the lower head is #0 and the upper head is #1... is it right? I don't remember... well, I cleaned both with care...]

I also checked the heads with a multimeter: same values, more or less. I'm wondering if it can be a faulty component on the board on the head #1 (while the head #0 is ok)? Unfortunately I can't swap the two head connectors to see if it's an head issue or not because they're mirrored and can't fit the other plug easily.
 
I don't know if hand cleaning the heads is as good as using a cleaning disk with solution. I only use the disk method and it works every time.
 
Stone said:
I don't know if hand cleaning the heads is as good as using a cleaning disk with solution. I only use the disk method and it works every time.
Click to expand...

I haven't a cleaning disk because of its price + shipping. But I cleaned many drives manually without problem, even some very, very dirty.
I guess a dirty head isn't the problem with my drive... electronics, maybe?
 
I don't know what very, very dirty means but I do know that it's not the dirt you see but rather the dirt you don't see, i.e., oxide residue from floppy disks, that fouls the drives' heads.
 
Stone said:
I don't know what very, very dirty means but I do know that it's not the dirt you see but rather the dirt you don't see, i.e., oxide residue from floppy disks, that fouls the drives' heads.
Click to expand...

oxide residue from old, bad, floppies is the worst problem I had here. A lot of bad floppies... You have a good unit, insert the floppy, and suddenly the unit stops to work. Read errors, write errors.... I always solved manually, some alcohol and a small piece of cleaning tissue and a lot of care. Never had a problem. I will try to clean it once again, but I'm quite sure the heads are already clean.

BTW: head #0 = lower, head #1 = upper.. is it right?
 
There is a repair technique sometimes seen in the Automotive world called BFI. It stands for "Brute Force and Ignorance". I'm not trying to throw rocks at anyone or belittle anyone's troubleshooting techniques. But the simple fact is that you can do more harm and run up more expenses by not using the proper tools and techniques than you save by not doing it the "right" way. I have actually seen a tech trying to do engineering changes to circuit boards with a 750 watt soldering iron. It did not turn out well. Be advised that there are often more than one "right" way. And some of them are more "right" than others.

Consider for a moment that a floppy drive is made to have a rotating mylar disk pressed against the head and then have that disk rubbed against the head under pressure from another head or a pressure pad. It's made to cope with those stresses. A floppy cleaning disk is pretty much made to do something similar as it cleans. The drive is not made to have a Q-tip or other material pressed against the heads in random directions. One can easily bend the metal springs that sometimes support the head and/or crack the sometimes old brittle plastic that support the heads and or floppy disk. One can easily end up with a clean enough head that's now out of alignment.

As for the expense of the cleaning disk, consider for a moment that we all go around this life one time. The time you spend troubleshooting any problem has value. Perhaps more than the cost of the cleaning disk. But I understand there are situations where someone in this hobby simply cannot come up with the price of the proper tool no matter what. In that case it may be time to improvise. I've seen examples on the web where someone took apart a floppy and replaced the mylar media with something similar to what comes in a cleaning disk. I'll poke around and see if I can come up with a link to one of those.
 
I have a similar problem on a Mitsubishi 360K floppy drive. The second (top) head doesn't work quite right and gives lots of errors. It will work OK as single sided though. I've seen that kind of problem before, but don't know exactly what causes it. Heads cleaned in a billion different ways.

I'd say there is a possibility that at some point a deformed disk jacket snagged on the head and threw it out of whack. It could be electronics - if you had an identical second drive you could try switching out the logic board. It could also be something mechanical - try gently pushing down on the top head while formatting and see if that makes a difference.

(And I have seen and manually cleaned drives so dirty that a cleaning disk would not make a dent in)
 
DDS said:
There is a repair technique sometimes seen in the Automotive world called BFI. It stands for "Brute Force and Ignorance". I'm not trying to throw rocks at anyone or belittle anyone's troubleshooting techniques. But the simple fact is that you can do more harm and run up more expenses by not using the proper tools and techniques than you save by not doing it the "right" way. I have actually seen a tech trying to do engineering changes to circuit boards with a 750 watt soldering iron. It did not turn out well. Be advised that there are often more than one "right" way. And some of them are more "right" than others.

Consider for a moment that a floppy drive is made to have a rotating mylar disk pressed against the head and then have that disk rubbed against the head under pressure from another head or a pressure pad. It's made to cope with those stresses. A floppy cleaning disk is pretty much made to do something similar as it cleans. The drive is not made to have a Q-tip or other material pressed against the heads in random directions. One can easily bend the metal springs that sometimes support the head and/or crack the sometimes old brittle plastic that support the heads and or floppy disk. One can easily end up with a clean enough head that's now out of alignment.

As for the expense of the cleaning disk, consider for a moment that we all go around this life one time. The time you spend troubleshooting any problem has value. Perhaps more than the cost of the cleaning disk. But I understand there are situations where someone in this hobby simply cannot come up with the price of the proper tool no matter what. In that case it may be time to improvise. I've seen examples on the web where someone took apart a floppy and replaced the mylar media with something similar to what comes in a cleaning disk. I'll poke around and see if I can come up with a link to one of those.
Click to expand...

I understand and in some way agree with you. But there is also something called extreme caution, lot of care and use of common sense. DIY isn't always synonymous of BFI.
I use a lot of care cleaning my unit heads and it seems I'm doing it the right way, since I did it for many years without a problem (or I'm very lucky, LOL).

...and I know how much fragile is a fdd head, because I had to fix my IBM XT FDD head somebody else broke, transplanting the thin metal foil with the head from another drive. Nothing I want to do again, if I can avoid it :-/

About money vs. time: in an absolute sense, you're right; but when we're talking about free time, it's another matter. I'm trying to fix this FDD problem because it's raining and I can't take my bike and burn some gasoline riding... I mean I'm sitting here with my tools because I have nothing better to do ^_^

--Giovi
 
I'm going out on a limb here but I hate head cleaning disks.

The biggest issue I have with them is that that material that they remove stays embedded on the cleaning surface. The head then slides back and forth over the removed material which can either a) be redeposited back on the head or b) causes damage to the head via the friction/sanding effect it has. Cleaning disks are fine if your cleaning off a small/moderate amount of magnetic material that has come adrift, but if the drive has been stored and has dust, fluff etc it can in extreme cases ruin the head. There are numerous articles about pro's and con's of cleaning disks on the web so obviously everyones opinion of cleaning disks will be different; this one is just mine based on my experience.

I always use a cotton tip (Q-tip for the Americans) which has been moistened with isopropyl alcohol to clean the heads. It's soft, plus as soon as its dirty you change it out for a new one and keep cleaning. Personally I have never ruined a head using this technique BUT as stated earlier I am sure if you do it wrong using a screwdriver or something you could. It also takes a lot longer as you need to disassemble part of the drive to get to the heads; but as a bonus you can give everything else a lube & clean while you are at it.

Extra tip: If you do use a cotton tip to clean the heads you may need to 'flatten it out' a little as it's too fat to fit between the heads. I use a clean pair of pliers to squish the end down and also in certain cases bend the stem to a 45 degree angle to allow better access.
 
That's an excessive amount of work for a process that sometimes needs to be performed several times a week. :) Yes, I have thousands of old floppies and the constant use of them requires continuous maintenance on the drives I use them in. I guess for the casual hobbyist disassembly is not a problem but I just can't afford all that time and labor over and over again.

I've been using the cleaning disks for over 25 years without any problems and don't know that I would have been able to remain focused if I needed to disassemble, clean, reassemble and check these drives on a regular basis. I don't think I would have time to do the work I had at hand if it were not for the time-saving efficiency of these cleaning disks.
 
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