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Old 15 November 2020, 10:07   #1
Marty_McFly
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Floppy drive wheel. How to disassemble it without breaking?

Hi guys,
I am attempting to repair an old CITIZEN Amiga slim drive, but to access to the components of the pcb I need to remove the black wheel to which the floppies are hooked and rotate when are inserted into the drive.

This is the front side of the wheel

[/url]

And this is the rear side



Is there a way to remove it in a safe way?
My main concern is that trying to pull it away, it could damage hopelessly.

Is there anybody that can help me?
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Old 17 November 2020, 00:51   #2
Bruce Abbott
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There should be a grey plastic circlip holding the shaft in. Just expand it by wedging something into the slit and it should pop off, then the shaft will come out easily.

Here's a picture of a Citizen laptop FDD with the circlip removed.
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Old 17 November 2020, 16:06   #3
Marty_McFly
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Hi, thank you very much, your tip worked!

Now I am trying to understand what's happened to this drive.
The 2 engines work, I tested both of them. The ready signal is ok, but after inserting any floppies the second engine does not turn on. The problem is that the current does not arrive to the second engine, I mean the one that pull and move the belt.

Any ideas? Some capacitor?
It seems that there are no broken tracks on the pcb.
It stopped working since I reassembled it and closed its case after the replacement of the belt. I noted that the drive did not run and opening the case I noted a stench of burning, like of plastic or component burning.

Attached you can see a photo of the pcb. The wires to the 2nd engine (red and blue) are visibile on the north-east side of the picture.



Thank you very much for any helps.
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Old 17 November 2020, 19:34   #4
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Which motor do you mean by 'second engine' - the disk motor (,with the drive belt) or the track motor (that moves the read/write heads)

Have you checked the disk presence switch to make sure that works?

The ready signal should only come on when the disk is detected, and when the disk motor gets up to speed.

Have you used Amiga Test Kit to check the floppy drive signals?
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Old 17 November 2020, 19:56   #5
Marty_McFly
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Thank you for your aid.
I mean the disk motor. I confirm that the disk presence works on the base of more tests I made by Amiga SysTest (Test Kit).
Every time I press with a finger the switch (you can see it in the picture, below the hole near the writing "C70-1070" on the left) SysTest confirms the READY sign but the disk motor remain turned off.

Is there some datasheet of this drive? Maybe a way to find the problem could be with an examination in reverse of the circuit, starting from the disk motor until the READY switch, because in my opinion the problem is in the middle of these 2 points. Some component in the middle. Do you agree?
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Old 17 November 2020, 20:37   #6
solarmon
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I have quite a few of these external Roctec / Citizen slim drives, so I can help you check/test anything against a working one.

You are right, with this drive the READY signal does seem to appear even with and without the disk inserted.

What you should find is that when the motor signal turned on (press F5 when you in the Signal Test page in Amiga Test Kit) then if will disappear, and only appear again when you put in the disk (and the disk presence switch is working) and the motor is spinning (you should see the Index Pulses counter incrementing) fast enough and then the Ready signal appears if everything is working.

When the disk motor is on, the LED on the drive should also be on - so do you see this? The disk motor turns on when it gets a Motor signal is on - so you need to check that the motor signal is getting through to the drive.

The Index pulses will only increment when the disc motor is on and the hall effect sensor is working.

What happens when you turn on the motor signal with F5 and have a disk in (or hold down the disk presence switch)?
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Old 17 November 2020, 21:44   #7
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Hi, when I press F5 only the motor n.1 moves on, the n.2 remains stopped.
In any case I confirm that every time I press the presence switch the led lights on and on SysTest the READY signal is recognized.
Please see photos below:





Just a note about the area with the wires that go to the motor n.2 (belt), I zoomed that area.



The only way to turn on the motor is linking the red cable to the pin of the component circled in blu. But it is not the correct link because the motor remains always turned on, ignoring the pressing of the switch. I think because it takes 5v from there.

Could you check on your drives If there is some other point to which I could link the red wire, just to isolate the bad components? Because in my opinion the not working component could be in that area... a datasheet would help a lot

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Old 17 November 2020, 22:15   #8
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Do you have continuity between the red wire pad on the disk motor, and the top right pin of the component. That pin should join to the red wire pad which should join to the motor view the red wire.

If you use the logic probe, on that pin or pad you will see that it pulses high when the motor is on.

The red and blue wire is basically the two ends of the coil of the disk motor.

I noticed in your picture of ATK, that the WPR (Write Protect) switch signal is not active. When you press the Write Protect switch down then the WPR signal should go off.

When you press the disk presense switch down, the disk motor (and LED) should come in briefly and then go off again. It is only when you press F5 to turn on the motor signal that it should stay on.

Also there is no TRK0 (Track 0) signal. If you repeatedly press F6 it should step in and out of Track 0 and the TRK0 should go on/off. (I noticed on this Citizen drive, for this behaviour to happen, the motor signal must be on)
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Old 18 November 2020, 01:01   #9
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Hi, please have a look at these photos.
Here I pressed the presence switch + write protection switch:



Here I pressed F5 Motor on/off but the motor n.2 remained turned off, no signs.



Returning back I pressed F6 (READ) in the main menu of floppy mode keeping pressed presence switch, and this is the resulting screen:



In any case I discovered that the aluminium capacitor linked to the motor n.2 resulted not working properly (gives me 2uF insted of 10uF), and I replaced temporarily with an electrolitic of the same values. But notwithstanding the motor n.2 remains unactive...



Only a couple of notes:
The led lights on only with F5 signal test selected. Out of that option it never lights on, nor for a short time.
If I link the red wire pad to the pin with the text "0W" the motor n.2 turns on and at high speed. But I think that it is not a correct link, or not?
As written with a such link the motor remains active and ignore any pressure on presence switch.
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Old 18 November 2020, 08:47   #10
solarmon
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If you press the presence switch, WPR signal should appear. Then when you also press the write protect switch then the WPR signal should disappear. This may be a separate issue, but it should stop the drive from working in other ways.

Apologies, I was wrong about the component pin. The red cable pad actually goes to the + (positive) pad of C36 (the one you replaced). The blue cable pad should go to the - (negative) pad of C39.

If C39 (and C35) has leaked you need to clean up the area and test continuity of the pads and traces.

The TR9 component seems to be a voltage regulator. The red cable pad is joined to the middle pin of it (the one between 'BF' and '0W' - and also the large pin on the other side (next to the 'TR9' label).


Last edited by solarmon; 18 November 2020 at 09:20.
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Old 19 November 2020, 02:02   #11
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I am really exhausted. I just ended 3 hours of attempts.
The only sure things are that
1) the 2 capacitors near the motor n.2 work fine. No leaked.
2) to the motor n.2 does not arrive the 5 volt current, exactly to the red pole no current.
3) a critical role seems to be played by the component TR9. It seems a transistor PNP. The 5 volt arrive only to the pin n.1 near the text 0W. If that transistor is a PNP then that pin could be the "Emitter" and this could explain the output of the current from the mid pin and the opposite large pin on the other side of the component, that in my case do not work.
In my case this transistor could be damaged, and this would explain because the only +5v current is on the Emitter and is the only presence of current in that zone. There are no other points where there is a 5v active of current. It is all dead.
For the rest I checked all the tracks and there is continuity, no broken tracks on the pcb.
If you agree I could send to you the drive for repairing, if you are able to do it. And if you can replace that component.
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Old 19 November 2020, 08:39   #12
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I do have spare Citizen drives that you can buy. You can also send me your drive as part payment. Please PM me.
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Old 19 November 2020, 13:59   #13
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I made some progress in trying to understand the circuit related to the disk (spindle) motor.

TR9 a transistor/voltage-regulator.

AN8235S is a 3.5-inch FDD Spindle Motor Controller - the specs sheet can be found at:

https://www.datasheetarchive.com/pdf...M&term=AN8235S

I have updated my diagram to show the connections based on my new understandings.

On the AN8235S chip, Pin 5 (SS) is the Start/Stop signal - which is effectively the Motor signal. Pin 15 (DO) is the output going to TR9, via R36 (330 ohm) which feeds the red end of the motor with 5V from VCC rail. Pin 16 connects to the blue end of the motor.

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Old 19 November 2020, 15:57   #14
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Thank you very much my friend.
In my opinion we are near to the solution.
In the case of no solution I would give away that drive to you.
I will find in any case a way to pay/return your availability.

I would focalize the attention once again on the TR9 transistor. I made some search and It results to be more exactly a PNP bipolar smd transistor. I tried to check if ii works fine some minute ago with a multimeter and probably -as supposed last night- the fault is there.
Please have a look at the picture below and see the letters...



It would be really helpfull if you could make the following test on a working transistor of your citizen drives.
Pin A and Pin C work like 2 anodes and the pin B is the cathode. If you put the red pointer of a multimeter on A and the black one on B (set to diode mode) you should see some voltage. The same or similar voltage should result if you put the red pointer on C and the black one on B.
In my drive on the latter gives a voltage. The first link (A and B) gives error. So this could be the fault.

In any case please let me know what results from the test on your drives.
Thank you very much! I will study in any case your last clarifications.
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Old 19 November 2020, 16:25   #15
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The pin you have labelled as 'A' is the VIN pin and this should be connected to VCC which should be 5V.

The pin you have labelled as 'B' is the VOUT pin and should be low when the motor signal is high, and should be high when the motor signal is low. (since /MTR is 'active low').

Do you not get 5V at 'A' (VIN)? If not, then you need to check the trace. It should be connected directedly (have continuity) to the VCC pins - check continuity to pin 1 and 2 on the floppy connector (CN1).

In terms of the test, yes I get a voltage reading for both tests. But I would check that VCC is getting to the TR9 component - and the other traces going to/from it. Make sure the traces are OK first.
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Old 19 November 2020, 17:03   #16
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Yes the traces are ok, If you look at my older posts I already checked and written that the only point in which with a multimeter results a +5v is pin A. There is continuity with VCC, already checked but cannot be differently, because +5v comes from there. About the test do you confirm that putting the pointers as written you have in A-B and C-B some voltage?
If yes I could need only of that component...

Please make the test with the drive turned off and using the multimeter in diode/continuity mode test.

Last edited by Marty_McFly; 19 November 2020 at 17:10.
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Old 19 November 2020, 19:22   #17
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Quote:
Originally Posted by Marty_McFly View Post
Yes the traces are ok, If you look at my older posts I already checked and written that the only point in which with a multimeter results a +5v is pin A. There is continuity with VCC, already checked but cannot be differently, because +5v comes from there.
Oh, sorry, I forgot you had mentioned that already.

Quote:
Originally Posted by Marty_McFly View Post
About the test do you confirm that putting the pointers as written you have in A-B and C-B some voltage?
If yes I could need only of that component...

Please make the test with the drive turned off and using the multimeter in diode/continuity mode test.
In diode continuity mode, I do get voltage across A-B (0.673V) and C-B (1.816V).

I suspect your C9 is maybe the component that has burnt?
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Old 19 November 2020, 20:12   #18
Marty_McFly
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Quote:
Originally Posted by solarmon View Post

I suspect your C9 is maybe the component that has burnt?

maybe you mean TR9 ?
Would you have this component to sell to me?
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Old 19 November 2020, 20:21   #19
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Quote:
Originally Posted by Marty_McFly View Post
maybe you mean TR9 ?
Would you have this component to sell to me?
Sorry, yes TR9.

I don't have the component, but you should be able to get an SMT/SMD PNP transistor / voltage regulator with the same pinouts.
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Old 19 November 2020, 23:01   #20
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off topic: Is their a Arduino Floppy Test project? Or Amiga/PC is best?
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