Laptop FDD Replacing

This Is Information About How To Replace (HP OB 5000c) Laptop's FDD with standart 34 PIN FDD .



Most of the laptop's FDD are 26 pin. The problem is that they are mounted in additional plastic case (this is made for convenience of the user , for instance you may easily remove the drive)and in this box there is additional wiring to the drive. Remove this case ,then carefully take out the wire (You are going to use it when connecting the new drive) , see how many pins your's FDD has. If they are not 26 I can't help you (try finding the pin-outs for this drive , or for the port on the mobo ). So now we have a small wire which has 26 pins on the one side (where it was connected to the FDD) and X on the other (where it is connecting with the mobo).On table 4 You can see the pinouts for 26 and 34 PINS Floppy Drives.

1.    Background of the plastic box (inside Cannon md3661 FDD)

Bacground Of The Box
















2.    Background of the plug

'THE' Cable




As You can see on the one side (where the cable is connecting with the FDD) there are 26 pins but on the other side (where it is connecting with the mobo) there are 20 pins









3.    Cable <=> Plug

26 pin cable

20 pin plug

 

26 pin cable

20 pin plug

1

1

 

14

15

2

3

 

15

14

3,5

5

 

16

7

4

2

 

17,19

17

6

11

 

18

16

7

N/C

 

20

8

8

4

 

21

18

9

13

 

22

19

10

12

 

23,25

9

11

N/C

 

24

20

12

6

 

26

10

13

N/C

 

 

 

4.    Pin-Outs  
(if somebody have different pinout he can send it to [email protected])

NON Standart
20 PIN plug

26 PIN
FDD

Standart
34 PIN FDD

   Signal

1,5

1,3

(+5V)

   VDD

14,17,18,9

15,17,21,23

(GND)

   GND

3

2

8

   /IDX

8

20

26

   /TR00

19

22

28

   /WPROT

20

24

30

   /RDATA

11

6

34

   /DSKCHG

2

4

14 / 12

   /DS0 / 1

12

10

10 / 16

   /MTR0 / 1

7

16

22

   /WDATA

16

18

24

   /WGATE

N/C

13*

2

   /DRVDEN0 / 1

10

26

32

   /HDSEL

6

12

18

   /DIR

15

14

20

   /STEP

14,17,18,9

15,17,21,23

Any Odd #

   GND

* In My Case Pin 13 is not connected. Also In the pin-ots sheet
from whom I colected the information it was written that
pin 13 is NOT CONNECTED . If somebody knows something
more, please mail me : [email protected]



5.   Signals & Descriptions

Signals

Descriptions

  /IDX

  Index Pulse (Prodused by the spindle motor for timing)

  /MTR0 / 1

  Motor On (0 = DOS A:   /    1 = DOS B:)

  /DS0 / 1

  Drive Select (0 = DOS A:   /    1 = DOS B:)

  /DIR

  Direction (A low here changes the direction of the head stepper motor)

  /STEP

  (Each pulse here cause the head stepper to make a step)

  /WDATA

  Write Data

  /WGATE

  Write Gate (Write Enable - a low turns on the write circuit)

  /TR00

  Track 0 (A low puts the head stepper over track 0)

  /WPROT

  Write Protected

  /RDATA

  Read Data

  /HDSEL

  Head Select (A low selects head zero)

  /DSKCHG

  Disk Change Switch

  DRVDEN0 / 1

  Drive density selection (0=High  /  1=Low)

Important Notice : In Some cases the standart 34 PIN FDD does NOT
work when connected at PINS #14 and #10 (Signals /DS0 and /MTR0).
I these cases connect the drive to PINS #12 and #16 (Signals /DS1 and /MTR1)



Usefull links

How Magnetic Disks Work  - very eloquent document about magnetic disks especialy for floppys
Probing The FDC  - it does'nt matter that it is relating atari, read it to understand the FDD and FDC
www.ohmslaw.com  - very nice site relating making robots from (FDD) hardware and other.

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