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Old 06 September 2019, 22:02   #1
solarmon
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Panasonic JU-253-043P floppy drive - _RDY (READY) signal not asserted

Hi,

I have an internal Panasonic JU-253-043P floppy drive that does not seem to assert a _RDY (READY) signal:



This has been tested on an A1200 rev 2B, but I don't think that is a factor.

The switches have been set correctly - the same as another working Panasonic JU-253-043P floppy drive on the same A1200, using the same power and data cables:



This floppy drive has had the usual heads cleaned and motor gear lubricated, but without the READY signal then we haven't reached that stage yet.

Using DriveTest shows that everything else is working OK, apart from the READY signal:



But since no _RDY signal is asserted, then DF0:???? is shown and X-Copy cannot therefore see a disk in DF0:



I will be looking to replace the 10uF 35V cap by the fly wheel, and I've still to check/compare the trimmer resistor with the working drive, but the fly wheel seem to be spinning at a decent speed:



and there is another yet to be identified cap on the rear board:



Can anybody provide any advice on the circumstances that would make a floppy drive not assert the _RDY (READY) signal?
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Old 06 September 2019, 22:19   #2
idrougge
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Have you tried flipping the RY/DC switch?
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Old 06 September 2019, 23:01   #3
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Quote:
Originally Posted by idrougge View Post
Have you tried flipping the RY/DC switch?
Thanks! That is a very good point! I was so focused on the READY signal that I didn't try the DISK CHANGE one.

I tried that and the drive did assert pin 34 to low, and X-Copy detected (or accepted) that there was a disk in the drive (due to the DISK CHANGE signal now asserted on pin 34), and I was able to initiate a CheckDisk to start the alignment process:



However, I notice that the DiskCheck was going very very slowly, and was showing all 2's for each block. And I needed to eject and insert the disk to trigger a DISK CHANGE signal if a wanted to do another DiskCheck otherwise X-Copy would state that there was no disk on the drive.

I tried to fine tune the alignment by loosening the tracking motor screws and rotating it after every block check. But this trick did not change anything and X-Copy CheckDisk continued to show all 2's.

So, at the moment, I don't know whether it is not working because of misalignment, or if there is (probably) still something inherently wrong with the drive, considering this READY SIGNAL issue. Or both.
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Old 07 September 2019, 09:30   #4
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I know it doesn't help your situation exactly but in order to rule out a disk drive fault, connecting the drive using the following adaptor will at least let you know the drive isn't at fault because it requires no drive modification to be used:

http://www.ianstedman.co.uk/Amiga/de...daptor_v2.html
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Old 07 September 2019, 11:31   #5
solarmon
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Quote:
Originally Posted by lesta_smsc View Post
I know it doesn't help your situation exactly but in order to rule out a disk drive fault, connecting the drive using the following adaptor will at least let you know the drive isn't at fault because it requires no drive modification to be used:

http://www.ianstedman.co.uk/Amiga/de...daptor_v2.html
This is not a PC drive that needs modification. It had a switch that allows you to set pin 34 to RY (Ready) or DC (Disk Change).

I have another working drive that is the exact same make and model.
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Old 07 September 2019, 20:07   #6
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I replaced both caps with 10uF 35V ones and that did not change anything.

Amiga Test Kit's floppy drive Signal Test showed that INDEX pulses were not detected.

Investigating this INDEX signal was not working I put a logic probe on the hall sensor IC on pin 2 (top right in the picture below):



On the working drive, this was pulsing everytime the magnet on the fly wheel went past it.

However, on the faulty drive, this was not pulsing.

So it looks like a faulty hall effect sensor IC - and I need to find a source for this 4-pin SMT package, possibly one of:

http://www.hallsensors.de/Hall-IC.htm

http://www.hallsensors.de/CYTY101A.pdf
http://www.hallsensors.de/CYTY108A.pdf
http://www.hallsensors.de/CYTY105A.pdf
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Old 08 September 2019, 09:45   #7
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Only one I could find is this:

https://rover.ebay.com/rover/0/0/0?m...2F401559972998
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Old 19 September 2019, 10:16   #8
solarmon
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Quote:
Originally Posted by lesta_smsc View Post
Thanks for checking.

Looking at the data sheet for it, it does not look to be the right pinouts.

I did go ahead and got some CYTY101A from:

https://www.sonnecy-shop.com/en/insb...4.8-mv/mt.html

and soldered it on as best as I could. However, the same behaviour - no pulses coming out of the output pin.

I don't know whether it is because it is the wrong hall effect chip, or there is another component issue that is preventing the index pulses from being generated.

I damaged the original hall effect chip when removing it (with soldering iron tweezers) - so I can't go back to that. I don't want to take out the hall effect chip from my working floppy drive. So I'm a bit stuck at the moment!
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