Getting one working Floppy Drive from two non-working ones

[solarmon]

It's the small one abit further down to the right in that picture, right by the fly wheel. There is a magnet on the rim if the fly wheel that passes over it as it rotates by.

[Sim085]

I attached another image. Is the hall effect sensor the one in the yellow box at the top or the orange box at the right bottom corner? (Sorry I am a newbie in these things, tried to search on google images but cannot find a match).

EDIT: Ok, I think I got it. Changed attached image. Am I correct that is the hall effect sensor?

Originally Posted by solarmon

It's the small one abit further down to the right in that picture, right by the fly wheel. There is a magnet on the rim if the fly wheel that passes over it as it rotates by.

[pipper]

...deleted

[solarmon]

See my thread on a similar subject here:

http://eab.abime.net/showthread.php?t=98729

The hall effect sensor is this black chip in the middle:

[Sim085]

Will go through that thread. I will also try to transplant the hall effect sensor from the dead drive to this one to see if that changes anything.

Originally Posted by solarmon

See my thread on a similar subject here:

http://eab.abime.net/showthread.php?t=98729

The hall effect sensor is this black chip in the middle:

[Sim085]

I have checked the specification of the hall effect sensor on the other thread. From what I understand when the chip detects something it should output 2.45V to 2.55V. Is this correct?

Therefore I thought - If I go to Amiga Test Kit Signal Test screen, and I push 2.45V on the output pin of the Hall Effect Sensor, the should the pulse index increase by 1 each time I apply the 2.45V? Or ... I'll just burn everything?

If it worked then it would be proof that the problem is the hall effect sensor.

[solarmon]

I haven'y measured the voltage so I cannot say. I have been using a logic probe which will indicate a high or low signal.

What I have observed is the following behaviour of the hall effect sensor pins and test points (TP):



Pin 2 seems to be the output and when the motor is turned on, it will go HIGH and with LOW pulses for each time the magnet passes the hall effect sensor. This signal goes to the IC on the right for further processing.

This is the bahaviour on a working Panasonic drive. I do not get the LOW pulses on my non working Panasonic drive, even with a replacement hall effect chip. Which I do not know if it is the correct one unless I swap it out with the working drive, which I'm reluctant to do.

[Sim085]

Originally Posted by solarmon

I'm reluctant to do.

I would also be reluctant. I would not do it. Only reason why I am doing so much experimentation is because in my case both drives where not working in one way or another and I reasoned (wrongly it seems) that I could "easily" get a working drive out of the two

Anyway, I used the diagram you provided and I would think I have the same exact results. It is hard to test the low on pin 2 as to get a high you need to turn the motor on and not sure if the dip in voltage when the magnet passes over is long enough to be observable. But to me it looked like stuck a little less than 5v.

[richud]

Hi, thought I would post here as this is top google hit about it...hope it helps someone.
I have both a JU-253-043P and JU-253-033P which both had/have issues.

The 043P didn't like reading parts of disks sometimes (repeatably at same points on the same disk) and sometimes was fine, a bit strange. For example I could take several games, load them all fine one day - next day all would fail to load at various repeatable points.
Did a lot of fiddling with track0 position sensor, motor position and top head, eventually replaced caps with some SMD 1210 ceramics. Old caps capacitance was fine (didnt measure ESR though!) and no obvious leakage signs.
I have just borrowed an external drive to boot the wonderful Amiga Test Disk (ATK) in DF1, then able to redo calibration (which ended up on same as marks to begin with) it now seems ok, so not sure if was caps or its just dicky and the period between dickiness has just increased.

The 033P spins up but does nothing after track0 seek 'failing', like it cannot find track0 because sensor is in wrong place. After much fiddling, still nothing.
As now just borrowed external drive and can run ATK - discovered there are no index pulses.
So after reading this thread and others assumed the hall sensor was the problem....

Looking at solarmon's diagram (took me a while to get my head round it)

P1 5v
P2 output (held high)
P3 TP?
p$ GND

...and testing my non-index outputting one, I came to conclusion my hall sensor is in fact ok.

If this helps anyone with the drive unplugged and hall sensor in circuit
good drive resistances
1-2 4.92kO
1-4 2.349kO
2-4 7.28kO
3-4 1.152kO

bad drive (that i think also has an ok hall sensor)
1-2 4.70kO
1-4 2.795kO
2-4 7.5kO
3-4 1.590kO

Using multimeter between gnd(p4) and output(p2) [It is easier to probe the leg on the IC than directly on p2 when drives spinning!]
should show different when motors spinning to off on DC & on AC setting a kind of even fluctuation when motors running. Presumably it pulls the output low on each pass.
My multimeter has a frequency setting, and then a sub function to measure rpm - on both drives this read 0.3k rpm i.e. 300 rpm - so thus assume both hall sensors ok.
(Also you dont need disk sensor 'down' to measure things, should always ouput when its spinning)
The head testing on ATK also shows nothing like, alignments totally out, and disk read test on ATK all B's. (Im 99% sure thats all actually fine).
It seeks fine to 0 -40 -79 , spins fine, motor on/off fine, everything appears totally ok.

Thus in conclusion I think my hall sensor is ok, drive mechanics are ok, and the problem is sadly elsewhere....

Other notes
-----------
In ATK will only show index pulses if the 'disk in' sensor is down (one furthest in of the two), just having motor 'on' without that won't show any,

Testing voltage with drive powered on and then manually moving the motor plate magnet's around over the sensor didnt seem to produce any change on the output, this seemd a bit odd. Manually doing anything never got me any change. I would just go straight to testing it in ATK with motor spinning.

The Hall sensor chip on bad drive marked '250', other one has nothing descernable on it.

[sirlemonhead]

I have one of these drives with the same symptoms that I've messed about with on and off over the years.

Whatever I've done recently, the motor won't spin with the 5v line connected. If I connect nothing but the 12v and two ground wires to the power connector, the motor spins (though I've no idea at what speed) but as soon as I connect the 5v line, the motor stops.

I noticed this problem because the function in Amiga Test Kit to turn on the motor stopped working.

The drive was recapped years ago but that never fixed the problems I was having (no index pulses)

With everything connected, I'm seeing 12v and 5v at a few places, down at the PCB by the spindle. The 12v line will be at around 12.70v with the 5v connected (and no motor spin) and this drops to 12.10v when the 5v disconnected and motor spinning but I assume the load of the motor is what's dropping this.

Anyone any suggestions for what I can do or check to at least have the motor function correctly with Amiga Test Kit again so I can go back to try figure out the index pulse issue?

[mart1n]

I picked up an A1200 dirt cheap that came with a JU-253-043P. Long story short:
- Cleaned and lubed the drive
- ATK booted without an issue first try
- Second time it refused to work and continued to do so until I left it for the day after (... when it worked _ONCE_ and then gave up again)
- Replaced both 10uF SMD caps with new SMD caps (Panasonics)
- Still only worked once per day or so
- Decided to recap the A1200 to rule that out. No change.
- Tried another Citizen drive. No issues at all.
- I've been fiddling with the variable resistor next to the hall sensor but it doesn't seem to make a difference (originally at 19k ohms - tried anything from 6k to 35k).
- The drive works when the fly wheel decides to spin. This happens quite rarely but when it does the read test, head allignment etc works without any issues in ATK until I power cycle.

... then I stumbled upon this rabbit hole (thread)

I just made a little discovery. I can get the drive to work whenever I want to. I just have to move the magnet on the fly wheel a little bit (maybe 3-5mm) left to the hall sensor and then insert the disk. As soon as I power cycle I have to repeat this to get the drive working again. Not a fantastic user experience

Is the hall sensor RIP or is there something else with my drive?

[larsovef]

It seems like these Panasonic JU-253 can be hard to repair. I am working on one now, after the regular stuff: clean, lube, change caps the disk spins up but does not read. Upon initial boot up it does not even return to track zero. But it is ticking and searching. What to do next?

Originally Posted by mart1n

I picked up an A1200 dirt cheap that came with a JU-253-043P. Long story short:
- Cleaned and lubed the drive
- ATK booted without an issue first try
- Second time it refused to work and continued to do so until I left it for the day after (... when it worked _ONCE_ and then gave up again)
- Replaced both 10uF SMD caps with new SMD caps (Panasonics)
- Still only worked once per day or so
- Decided to recap the A1200 to rule that out. No change.
- Tried another Citizen drive. No issues at all.
- I've been fiddling with the variable resistor next to the hall sensor but it doesn't seem to make a difference (originally at 19k ohms - tried anything from 6k to 35k).
- The drive works when the fly wheel decides to spin. This happens quite rarely but when it does the read test, head allignment etc works without any issues in ATK until I power cycle.

... then I stumbled upon this rabbit hole (thread)

I just made a little discovery. I can get the drive to work whenever I want to. I just have to move the magnet on the fly wheel a little bit (maybe 3-5mm) left to the hall sensor and then insert the disk. As soon as I power cycle I have to repeat this to get the drive working again. Not a fantastic user experience

Is the hall sensor RIP or is there something else with my drive?