Xf551 head out of bound (newtronics mitsumi D503)

[manterola]

Hi All, 

I have a non-working Xf551. The head moves out of the diskette window range. The track 0 sensor is working correctly, the problem is in the other size (closer to the center of the diskette). 

If I ask for a disk formating the head moves nicely step by step from the outside to the inside, but finally start hitting the plastic border of the floppy window. 

First I thought the track zero sensor was wrongly located "too inside", but even after moving it as far as I can away from the center still the head hits the border close to the center of the diskette. 

I have little hope regarding this mechanics, but I want to try something else meanwhile I wait for a another d503 or other 360kb drive to show up in ebay with a decent price tag. 

BTW, I already checked that the xf551 works with another mech. Of my other xf551, so I concluded the problem it is NOT in the xf551 board. 

Thanks for any help. 

 

[+Nezgar]

Sounds like you've ruled out a lot already by swapping mechs with another drive.

 

It sounds like the stepper motor may only be capable of stepping in one direction, (inwards, toward track 39). Maybe signals intended to step outwards (towards track 0) are actuating as inwards, causing it to go "too far."

 

The stock firmware formats DSDD side 0 from track 0-39, then side 1 from 39 to 0, then repeats to verify.

 

So.. Not sure if the stepper motor in the mech is even installed in a way which could be accidentally be wired up incorrectly, or if its even accessible enough to replace that specific component...

[_The Doctor__]

you may have a failing stepper motor in that it's not reporting all steps correctly, or drives pcb may have a failing detection circuit... sometimes it can be failing connections or connectors/ribbons...

 

if you witnessed the mech preciously worked , but fails now... try a light cleaning and re-seating of any and all connections and sockets.. make sure ZIF tabs are opened then closed.... blow compressed air into the track zero top and bottom... take care not to damage any ribbons that are soldered or don't have release tabs... if pressure only insert and remove straight and with fingers or tool as close to insertion end as possible.

 

Lastly sometimes adjusting the stepper motor a full increment or two has made some temperamental drive work again (I've seen some folks spin them 180 degrees as well... this puts the spindle position opposite where it used to be.... and sometimes works.... if this works, you should consider replacing the stepper motor... though some folks go on for years after this..

 

barring the motor being wired up incorrectly, incorrect configuration, the wrong mech, or failing circuit... there isn't much else to say...

Edited September 12, 2019 by _The Doctor__

[manterola]

Thanks for your help, guys. You provided me with a lot of ideas and I was able to improve the situation. 

I tried different things along the weekend and I was able to make the drive to boot from double and single density disks. However, the head keeps hitting hard the end of run close to the track zero. No adjustement of the sensor, the stepper, etc make its better: it does not boot/read/work,  or it work but keep hitting and making hard to hear noises. 

I have not been able to format a diskette, either: I counted the steps while formatting and about 18 it is already at the end of the diskette window. 

I give up, I am still waiting for a good price floppy 360k mechanics. I already tried with a couple of 1.2m mechanics (modified to run at 300rpm) with different tracks numbers, step rates, etc and they worked but the disk produced are only readable by those and other 1.2m drives. 

Thanks again... 

 

Edited September 16, 2019 by manterola

[+Nezgar]

 

On 9/12/2019 at 12:25 PM, manterola said:

...even after moving it as far as I can away from the center still the head hits the border close to the center of the diskette. 

 

On 9/16/2019 at 2:28 PM, manterola said:

However, the head keeps hitting hard the end of run close to the track zero.

I'm confused. Track 0 is the furthest away from the centre of the disk.

 

Maybe a video would better illustrate?

 

Regardless, it's likely not aneasily servicable part... It's kind of sad that 360K drives are so hard to find nowadays considering how plentiful they were before everyone recycled their boring clone PC's...

[manterola]

I got a ju-455 360k floppy disk drive. It works great but I have two problems, one which I knew I will have: the drive is too long. So I will need to 1) get rid of the heatsink , 2)I might also need to move one of the large capacitors, and 3) put knew switching regulators in a 90 degree position so the floppy mechanism will go over the regulator.

But even if I do all of that, the drive faceplate and knob (is that the right word?)  is still prominent in comparison with the original mitsumi D503 mechanism.

I will keep waiting for a D503 a bit more or a Teac 360K which requires a simpler mod of the heatsink.

I hope to create a video of the existing non-working D503, this weekend.

Thanks!!!!

[+Nezgar]

Interesting... I acquired a spare Panasonic JU-455 mech earlier this year thinking I might test it in the XF-551, good to know ahead of time not to be optimistic about it fitting... Plus this one has a black faceplate, so it would look really strange in the XF-551 case anyway...

[luckybuck]

As of 2019, the most occuring mechanical fault is, that C14 on the rear side is defect?

[manterola]

On 9/20/2019 at 1:11 PM, Nezgar said:

Interesting... I acquired a spare Panasonic JU-455 mech earlier this year thinking I might test it in the XF-551, good to know ahead of time not to be optimistic about it fitting... Plus this one has a black faceplate, so it would look really strange in the XF-551 case anyway...

Finally, I got a d503 at good price, not tested and rusty..and with black faceplate. I clean it, got from staples (yes rusty staples) that were stuck  making the motor sound weird (they were there because of the magnets of the main motor) and lubricated it, and put the white faceplate from the non-working one.... and voila!. It worked. 

BTW. I discovered that ju-455s came with different faceplates, some more prominent than others. 

 

[José Antonio]

On 9/12/2019 at 1:25 PM, manterola said:

Hi All, 

I have a non-working Xf551. The head moves out of the diskette window range. The track 0 sensor is working correctly, the problem is in the other size (closer to the center of the diskette). 

If I ask for a disk formating the head moves nicely step by step from the outside to the inside, but finally start hitting the plastic border of the floppy window. 

First I thought the track zero sensor was wrongly located "too inside", but even after moving it as far as I can away from the center still the head hits the border close to the center of the diskette. 

I have little hope regarding this mechanics, but I want to try something else meanwhile I wait for a another d503 or other 360kb drive to show up in ebay with a decent price tag. 

BTW, I already checked that the xf551 works with another mech. Of my other xf551, so I concluded the problem it is NOT in the xf551 board. 

Thanks for any help. 

 

I think the problem could be in the lack of limitation of movement of the step motor, which the XF551 originally brought, but it could be missing in some like in the photos that I attach ...

[1050]

Clever. With the metal tab installed the step motor hits an OBstackle and reverts to the opposite direction of it's own accord. I would have thought it would be done with software instead myself, but what do I really know or even paid attention too.

 

Nice catch, next time I'm close to one of those I'll see it again for the first time correctly.

[manterola]

In my case the problem was fixed by changing the stepper motor. I used the stepper motor of a broken mitsumi d503 drive, and everything started to work. 

 

[_The Doctor__]

On 9/12/2019 at 3:49 PM, _The Doctor__ said:

you may have a failing stepper motor in that it's not reporting all steps correctly, or drives pcb may have a failing detection circuit...

first line of the trouble list I made. Glad you nailed it! COngrats!