NEC FD1157C

These drives are compatible with a standard Floppy interface.

Specifications

Capacity Formatted: HD 1.2 MiB; DD 700 KiB
Unformatted: HD 1.6 MiB; DD 1.0 MiB
Height 1.6 in / 41 mm
Width 5.7 in / 146 mm
Depth 8 in / 203 mm
Weight 2.6 lbs / 1.2 kg
Disk size 5.25“
Heads 2
Surfaces 2
Tracks/Surface 80
Track density 96 tpi (tracks/in)
Dit density HD: 9870 bpi; DD: 5922 bpi
Record method MFM
Rotation rate HD: 360 rpm; DD: 300 rpm
Shock rating Operating: 10 G; Non-operating: 30 G
Vibration Operating: 0.5 G @ 0 - 100 Hz; Non-operating 3 G @ 0 - 100 Hz
Seek time Track to track: 3 ms
Settle time 15 ms
Data transfer HD: 500 Kib/s; DD: 250 Kib/s
Power +5 V, +12 V
Power dissipation 4.8 watts
MTBF 12,000 POH
MTTR < 15 minutes

(Specifications come from an online datasheet downloaded from NEC on 2014-08-28.)

Jumper Settings

From http://jope.fi/drives/necflopp.txt:

Configuration 1: Non-twisted cable
USE MON VC HDE DEN M1 DCG LM1 LM2 DX
2 1 On 1 1 On 2 0 0 see note

note: Drive 1 (A:) has DX=0, drive 2 (B:) has DX=1

Configuration 2: Twisted cable (pin 10-16 twisted)
USE MON VC HDE DEN M1 DCG LM1 LM2 DX
2 3 On 1 1 On 2 0 0 1

note: Drive 2 and controller are on one the same side of the twist, and drive 1 is on the other side. Both drive 1 (A:) and drive 2 (B:) have DX=1.

Jumper setting options

(* is the default setting.)

Head Load Condition HS USE
Drive select & head load 1 1
Drive select 1 2
Head load 2 1
Drive select & motor on 1 3
Motor on 2 3*
Motor On Condition MON
Drive select 3
Head load 2
Motor on 1*
Display Lamp Condition IUS USC LED
Head load 2 1 1 and 4
Head load & Drive select 2 1 1 and 5
Drive select - 2 and 4
Ready - 3 and 4
Ready & Drive select - 3 and 5
Drive select - 2 and 5
Head load 1 - 1 and 4
Head load & Drive select 1 - 1 and 5*

Note: ”-“ indicates that the jumper position doesn't matter.

Density Switching
Record density High/Normal density signal DEN
High H level 1*
Normal L level
Normal H level 2
High L level
High H level 3
High L level
High H level Open
Normal L level
Rotation Change
Rotation in normal density mode HDE
360 rpm (“single speed mode”) 1*
300 rpm (“dual speed mode”) 2

Note: A rotation in a high-density mode is 360 rpm for both short plug and “HED”=1 and 2.[sic]

Disk Change/Ready
Disk change/ready signal output condition DCG
Ready signal 1
Disk change signal 2*

Basic Disassembly

⚠️ Use a J1 screwdriver or you will strip the screws! Screws on this drive are type J1 JIS screws. These are similar to Phillips screws, but not the same.

With the drive flat on a table, with door facing you, remove the screw on the right about midway down the chassis. This screw holds the RF shielding on. With the screw out, the shielding should slide forward towards the drive door. Lift the back up. You should be able to remove the shielding entirely. Reverse the process to put it back.

Extras

Cleaning video: