HP manual Cooling for D315 Models, Tach, FANSEL1 FANSEL2, Pwrfan, Cmd

Chapter 4 System Support

4.7.4.1Cooling for D315 Models

The temperature controller produces the Fan CMD (which varies from 0 to +2.5 VDC) that is applied to the speed control circuitry of the power supply assembly. The output of the speed control circuitry controls the power supply assembly’s internal fan and is also routed back to the system board and, in the default jumper configuration, is applied as the Fan Sink signal to the negative terminal of the connected fans. The default jumper configuration also applies + 5 VDC to the positive terminal of the fans. With the Fan CMD signal being varied from +0.5 to -7 VDC, the chassis and CPU fans will be driven by a voltage from about +5 to +12 VDC, depending on the processor temperature.

In a characteristically warm environment or should the speed regulation circuitry be inadequate or fail it may be desirable to have the fans driven by a constant +12 VDC by configuring both FAN_SEL jumpers to pins 1 and 2.

Note that the power supply assembly fan operates independently of the CPU and chassis fans.

CAUTION: Both FAN_SELn jumpers must have the same configuration (jumpers on the same pins). Different jumper settings (one jumper on pins 1 and 2 and the other jumper on pins 2 and 3) may result in equipment damage.

				Chassis Fan				CPU Fan
					Header			Header
				(-)	1			(-)	1
		Fan Pwr		(+)			Fan Pwr (+)
					2				2
			TACH					TACH
		NC			3		NC		3
Processor					FAN_SEL1		FAN_SEL2
					Header/Jumper Header/Jumper
						1	1		+12 VDC
			Fan Sink			2	2
Therm-						3	3		+5 VDC
	Super
SMBus
	I/O Cntlr.	PWR_FAN			Fan		Power Supply Assembly
AMD1030
Temp.		Header			Sink
			1
Controller				Fan					PS Fan
		Fan CMD				Speed		(-)
			2	CMD
						Control
							+5 VDC (+)
							PS
							Circuits

NOTES: Jumpers shown in standard configuration.

TACH function of the fan(s) not used.

Figure 4-12.D315 Model Fan Control Block Diagram

4-28Compaq D315 and hp d325 Personal Computers Featuring the AMD Athlon XP Processor

Second Edition – April 2003