M295XS Configuration

M2952
M2954

M2952SAU, M2952SYU, M2954SAU, M2954SYU Configuration

Family Alias : AL3'S

Terminal CN7

Pin	Status	Function
1-2	SHORT* OPEN	SCSI ID (bit value 1)
3-4	SHORT* OPEN	SCSI ID (bit value 2)
5-6	SHORT* OPEN	SCSI ID (bit value 4)
7-8	-	Spindle sync connection
9-10	Reset switch	Drive reset when shorted. This pins are normally connected to a momentary switch. Normal operation when open.
11-12	SHORT OPEN*	Write protection enabled when shorted
13-14	SHORT* OPEN	Enables onboard SCSI termination of the bus when shorted.
15-16	External LED	Use for connection of an external LED

Terminal CN6

Pin	Status	Function
A	SHORT* OPEN	When shorted the spindle starts to rotate when power is applied. When open the spindle will not spin up until a START/STOP UNIT is issued by the host.
P	SHORT* OPEN	SCSI bus parity check is executed when shorted.
D	SHORT OPEN*	Normal operation is expected when these pins are open. Short them for offline self diagnostics which will continue until the drive is powered off.

Orientation

The drive may be installed in one of five orientations; either PCA down or on any other edge. Inclination from vertical or horizontal should not exceed 5°.

Mounting Screw Fixing

When the mounting screw holes on the side of the drive are used, then use only the two pairs of outer holes. Do not use the centre holes in conjunction with only one of the outer holes. Drives with the suffix M accept M3 screws while drives with the suffix U accept #6-32UNC screws. The screw must not penetrate the drive by more than 4 millimetres to avoid damage to the circuitry or negation of any shock damping capability.

Grounding

Magneto-Resistive Read heads are a significant factor in the achievement of very high capacities in small form factor hard disk drives. These drives use Magneto-Resistive (MR) heads and therefore require special handling considerations. The MR head must be electrically biased in order to function, and Fujitsu use +5.5VDC on these drives. The voltage is generated by the drive electronics from the normal +5VDC and +12VDC rails, so standard power supplies and connectors may be used.

With the MR head biased in this way, it becomes important to avoid the possibility of discharge between the head and the media, so, in order to ensure operational reliability, the disk enclosure (DE) and hence the platters themselves are also biased to +5.5VDC resulting in zero potential difference between head and platter. This means that the outer casing of the DE is set at +5.5VDC rather than DC Ground as would be the case on a conventional drive.

Users must ensure that the DE casing is NEVER shorted to the computer system's frame or DC Ground.

Fujitsu have taken steps to minimise the possibility of accidental shorting by coating the DE with an electrically insulating material and by removing the earthing tag that would normally be present. Also the drive is protected against damage in the event of accidental shorting through the use of a protection circuit in the head IC. This works by quickly shutting off the bias voltage when it detects a voltage drop. Any read or write operation during this time will result in a hard data error. When the short is removed the bias voltage is automatically restored and read/write operations will again work normally. Pay close attention to the mounting specifications of the drive ensuring that no component of the system is likely to abrade the disk enclosure surface.

Cooling

Allow space above and below the drive to provide for adequate air flow. A 2.5 millimetre gap around the drive is recommended. Fan cooling is also recommended. The disk enclosure temperature, measured at top centre, should never exceed 60°C.