5.25 floppy disk drive slipping

[acer]

Hi all,
Recenty i got Apple II Europlus model, with two disk drives.
Machine itself is working ok, there was some bad capacitors inside PSU so i replace them,

Since i do not have any floppy disks for machine i tried to use ADTpro, via audio sockets.
And that part is working, but both floppy drives have issues.

I done some research online, but did not manage to solve problem.
When i start to format disk with ADTPro, drive is doing ok until it almost reaches end of disk.
At the end metal pin on head assembly slips out of grooves on white wheel and wheel just turning.

According what i found my track 0 is ok, at least looking ok, dot on wheel is in line with metal pin.
Rails are clean, head is cleaned, also grooves on wheel i cleaned.

Here two pictures of drive with head position at beginning and end position.


Anyone have idea what can cause this issue?
Thanks in advance.

 

[bibilit]

Hi, to be honest those drives are bullet proof and just need a little maintenance.

Rails just be cleaned and lightly lubricated, the rubber belt should be clean and the disk spindle should rotate freely.

be sure the motor is also not gummed.

the small metal pin can be twisted a little bit to make good contact,, but from your pictures i can see that the drive is comming in contact with each stop.

the only thing that can prevent the drive from working is a wrong speed (300 RPM) a bad logic chip or a damaged head.

 

[acer]

Logic board had bad 74LS125 so i replace it.
Moving white disk with hand, metal pin is in grooves all the time.
Rails are cleaned, head is moving freely, also head is cleaned.
Belt is ok
Spindle is moving freely, will try to make small movie, maybe it can help.

Will try to check rotating speed and also head resistance.

 

[bibilit]

74LS125 is pretty common issue, when the cable has been moved from one row to another in the board.

can you explain that part of the issue ? "At the end metal pin on head assembly slips out of grooves on white wheel and wheel just turning."

 

[acer]

Will try to make movie tonight, then you will see what is problem

 

[acer]

Here you can see problem

 

[bibilit]

Can be another bad chip.
Never seen this before, but can be the MC3470, can go bad if 74LS125 is damaged

You said you have two drives, maybe swapping cards, then chips can be the solution.

 

[bibilit]

http://archives.oldskool.org/pub/drivers/Apple/Apple%20II/Disk%20II%20servicing/AppleBox%20Disk%20II%20pages/older/AppleBoxService5.pdf

 

[acer]

Will try to swap cards, but this other drive have similar issues. So possible that both have bad MC3470.
Is there any possibility to get those chips somewhere, except aliexpress?

 

[bibilit]

Got mines from Aliexpress at some point, and worked just fine, and if not you can still have your money back.

 

[acer]

Will order one batch, 5 pieces are in batch.
Thanks
Will update about progress.

 

[acer]

At some suggested me on one FB group, i have disassemble everything,cleaned rails and white groove disk and now it is working ok.
Thanks everyone.

 

[bibilit]

IIRC is more or less what I said in the first place.