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sergeo-85
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Speed FAN CPU

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Z420 workstations
Microsoft Windows 10 (64-bit)

Hello,

Sorry, I use translator.

The motherboard was moved to the PC platform, the Xeon E5 2670 processor, original CPU FAN. BIOS: J61 v03.92
Please help me, CPU FAN all the time works at 100% although the temperature of the processor is 35-40 C. changing the settings in the BIOS did not give a result. How to fix this problem?

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DGroves
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the HP z420 uses a temp sensor that is embedded in the power cable, either use the z420 power cable on the new system

 

or make a temp sensor, it's a npn 2222A transistor

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sergeo-85
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Sorry, I use translator.

Thanks a lot for the answer!

Please specify, you are talking about the cable (adapter) from the motherboard to the power supply? Or from the power supply to the 220V outlet? Could you give the wiring diagram of the transistor pn2222A?

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DGroves
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HP z420 Power LED thermal sensor switch with holder part# 663218-001 (Modified)

 

https://support.hp.com/us-en/document/c03283193

 

From a previous post on a z800 (uses same temp sensor as z420)

 

temp sensor is in the power cable/speaker harness it uses a common npn 2n222A transistor

 

the transistor is in the power cable covered with the black heatshrink tubing, which consists of several wires bundled together

 

and the transistor itself is a small black plastic TO-92 case 

 

and will only use 2 of the 3 leads (Base, Collector, Emiter)

 

simply peal back the heatshrink covering where the transistor is located in the cable

 

and note the wire color that goes to each of the 2 connected leads (Grey/Brown as i recall) and replace the transistor

 

with the same lead connected to the same wire covering

 

here's a link to the 2n222a pinout/picture

 

https://components101.com/2n2222a-pinout-equivalent-datasheet

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sergeo-85
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I'm sorry, I realized I need this cable, right (663218-001)?

Cable HP Z420_1.jpg

As I wrote above, I have a PC case, and this cable is not. On the forum I managed to find front panel connector pinout.

HP Z420 Front Panel.png

Do I understand correctly that if I connect the transistor to 11 and 12 pins, the fan speed will be regulated?

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mdklassen
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> How to fix this problem?

 

If you replace the fan, are the symptoms still the same?

 

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DGroves
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the HP cable with the transister only uses two of the 3 leads  (Base. collector, emiter)

 

https://components101.com/2n2222a-pinout-equivalent-datasheet

 

the two leads used go to pins on the motherboard header where the pwr/hd light connections are

 

YOU MUST MATCH THE TRANSISTER LEADS TO THE CORRECT MOTHERBOARD PINS FOR CORRECT OPERATION

 

i would peal back the covering where the transistor is on the hp cable, note which color wire connects to each transistor lead and then on the connector end note which header pin connects to which color wire

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sergeo-85
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> If you replace the fan, are the symptoms still the same?

 

I don't know, I don't have the ability to connect another fan. But if the fan does not get control, I think the other fan will work the same way.

 

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sergeo-85
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I connected the transistor as shown in the link https://components101.com/2n2222a-pinout-equivalent-datasheet (the first pin-emitter transistor is not involved, second pin-resistor 1 KOhm + base transistor, the third pin-collector transistor) to the front panel of the motherboard on the 11th and 12th contact (as in the picture that I loaded).

Unfortunately, it did not produce results.

Still might be the reason I don't have a memory fan and a chassis rear fan connected?

What is a "motherboard header"?

 

 

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DGroves
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did you connect the transistors leads BASE/COLLECTOR to the correct motherboard header's pins?

 

note the header has two pins and if the  transistor pins are swapped it will not work and damage the transistor

 

last to the people asking about swapping fans, the issue is not fan related but caused by the motherboard not having it's ambient tempture sensor connected. this makes the motherboard bios think it's either two hot or a bad sensor and the default rensponce is to ramp fans up to max

 

personally i would buy a correct HP cable connect it and verify the fans work as expected and then if nessary remove the plastic covering to expose the wires and extend all the wires to the needed lenght

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