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Panasonic JU-475-3EAF not working

aitotat

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I just got Panasonic JU-475-3EAF (5.25" 1.2 MB drive) and i can't get it to work. I've tried it on a 386 and on a clone XT.

On a 386 POST just freezes. No matter if drive is set to 360k or 1.2M from BIOS. LED does not flash. I tried it as a A drive without B drive present.

Clone XT does not freeze so i can boot to hard disk. The 1.2M drive cannot read DD disks but drive motor and LED does turn on. I don't know if the XT bios knows how to handle 1.2MB drives so i tried single mode jumper (1M). I don't know if it sets the drive to DD or HD but it didn't help. I did try the drive as A and as B drive but results were the same.

JU-475-3EAF is made for Hewlett Packard and the jumpers are not quite identical to JU-475-3. There is no OP jumper but there is PA before DA and PH/NH selection below PA. Other jumpers are the same as on JU-475-3.

Jumpers are configured like this:
MDB, MM, PH, DA, DS2 and TM.
 

Chuck(G)

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I don't know what's up with your 386--controller accesses are timed, so it shouldn't hang. (I'm assuming that you mean you booted without a disk in the drive and the system hung).

Remember that this is a 96 tpi drive that your XT BIOS knows nothing about--and, in normal mode, spins at 360 RPM versus 300 for a 360K 5.25" drive. So, if you want to use this on your XT, you're going to need a controller with its own BIOS to match to make use of 1.2MB drives.

As far as I know, the Matsushita/Panasonic JU-475-3EAF is a standard JU-475-3, but with an HP-specified beige bezel. At least that was the case for the last one I saw.

Set the drive jumpers as shown on the Dell website.
 

Lorne

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If your drive happens to be toast, I have four 5 1/4" 1.2 MB floppy drives with beige bezels, and they're sitting here with nothing to do.

Two are Chinon, and two are Epson (but manufactured for HP with HP stickers on them).

You can have one for shipping if you need it.
It can't cost that much to send a half height floppy to Finland, can it?
Or, maybe they are as plentiful there as they are here.
 

aitotat

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I tried older multi I/O card on the 386 and now it won't freeze on the POST.

I tried to boot with known good 360k boot disk. XTIDE Universal BIOS displays some boot information so i know that boot sector was found. I couldn't get any further than that. Usually not even boot sector was found. Sometimes i got 02h error code (Missing address mark) and sometimes 04h (Requested sector not found). Now i only get FDD controller error message at the POST and 20h when i try to boot (Hard disk controller or drive problem).

I think the heads are stuck to cylinder 0. What should i do with it?
 

aitotat

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The drive didn't work with the first multi I/O card because i had drive swap jumper enabled. I should have connected the drive in the middle of the cable so it would have been detected as drive A.

Heads won't move properly (drive makes bad noise when it tries to move heads). Is there anything i could do to fix it?
 

Chuck(G)

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Does the head carriage move freely with no power applied to the drive? If not, it could be a matter of lubrication.

If so, it might well be a bad positioner (stepper) motor or one of its drivers.
 

aitotat

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It is very hard to move the head carriage by hand. I moved it a bit and the drive then returns the carriage when powering the drive. It makes loud noise when it returns the carriage.
 
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Chuck(G)

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I believe you may have identified your problem. Observe that the carriage is moved by means of a split metal band wrapped around and attached to a capstan attached to the shaft of a stepper. The shaft of the stepper should turn freely and easily.

It appears as if it does not. Fortunately (or not), the problem appears to be mechanical rather than electrical.

Lubrication and cleaning are the first order of business. Using a light solvent, such as paint thinner or even WD40, clean the rails. Observe and inspect for any dried grease on the rails and around the stepper shaft. If you must remove the stepper, be cautioned that you'll probably need to perform an alignment adjustment when you replace it.
 

MikeS

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I believe you may have identified your problem. Observe that the carriage is moved by means of a split metal band wrapped around and attached to a capstan attached to the shaft of a stepper. The shaft of the stepper should turn freely and easily.
Ummm, are we still talking about a JU-475? Every one I've ever seen (and I've seen a few ;-) ) had a screw-type head positioner...
 

k2x4b524[

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this is gonna seem a bit out of place but it could be the track 0 sensor. I had an alps 360kb do this, i got into it and i noticed the 0 sensor wasnt aligning up with the carriage when the drive powered on, but the heads moved to track 0 then banged like it couldnt find it. if you can try adjusting the track 0 sensor and see if that fixes it for you.
 

MikeS

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this is gonna seem a bit out of place but it could be the track 0 sensor. I had an alps 360kb do this, i got into it and i noticed the 0 sensor wasnt aligning up with the carriage when the drive powered on, but the heads moved to track 0 then banged like it couldnt find it. if you can try adjusting the track 0 sensor and see if that fixes it for you.
Yeah, I was kinda thinking that myself but forgot to mention it. Might be wise to make sure it's clean and the connections are good before you mess with the alignment; if a voltmeter/VOM/DMM is available, check the track 0 signal on pin 26 (with the drive selected and powered of course).
 

aitotat

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I tried to clean and lubricate the screw type head positioner. It didn't fix the problem but it helped me to see what the problem really is. There are two screws holding the head carriage on the head positioner. The screws seemed to be a bit loose so the carriage jumped off the positioner rail when step motor turned the screw type positioner.

I didn't have a correct sized screwdriver but i managed to tighten the screws a bit. It helped but not enough. At least the booting now starts so the drive succeeded to move to another cylinder. It is still noisy and boot did not complete but at least now i know what the problem is.

I need to get better screwdriver and remove the carriage to make sure it is completely clean. I assume the head alignment is necessary anyway since the carriage has already moved off the rail many times during the testing. Can it be done without the Panasonic Alignment Diskette mentioned in the service manual?
 

Chuck(G)

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I'm going to jump off a cliff here and say that unless you've actually loosened the positioner stepper motor, there's an excellent chance that you won't need to re-align the drive. There's an excellent post on this forum about aligning using a known-good ordinary floppy if you need to, however.

On those threads, you may want to use a drop of Loctite 222 to hold them in. Even a drop of nail polish on the screw heads may do the trick.
 

MikeS

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I'm going to jump off a cliff here and say that unless you've actually loosened the positioner stepper motor, there's an excellent chance that you won't need to re-align the drive.
Well, I'll join you in that jump, just like Cassidy & Sundance; I'd think it likely that the position on the screw would still align with a step of the motor. Worth trying anyway, before loosening the alignment screws.

Mind you, I've never seen those screws come loose, so maybe someone already tampered with that drive... is there a little bronze 'spring' in the carriage underneath the lead screw?
 
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MikeS

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I think we were pretty clear on which screws you were talking about (and next time maybe you could crop the picture to a little less than 1.5MB for those of us with dial-up access?). But at least I got the answer to one question; I see that the bronze spring is still in place.

But never mind taking pictures; do you get a track0 signal when the drive restores?

A tip, if by chance you have a dual-mode cable (for 5.25 and 3.5 drives): you can use jumpers and probes inserted in the 3.5 connector to conveniently manually step the drive and read the signals; the signals are all open-collector so you can't harm anything by grounding them.
 

aitotat

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I'm sure that those two loose screws were a symptom and not a reason for malfunction. I have now lubricated the rails (screw type rail and smooth rail that are on opposite sides of head carriage) and tightened the two loose screws.

HD diskettes can now be formatted, written and read just fine. There seems to be something wrong with DD diskettes. I don't know if this is related to the incompatibilities between 5.25" HD and DD drives.

The HD Panasonic can read DD diskettes it or some other drive has written. I have HD Teac drive that can read the DD diskettes written by HD Panasonic. DD Teac in Tandy 1000 SX and DD Panasonic in XT clone cannot read DD diskettes written by HD Panasonic. The can read DD diskettes written by HD Teac. I tried to format the DD diskette in HD and DD Panasonic drives but it did not made any difference.

Any ideas what i should do now? At least the head carriage now moves just fine.
 
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