Question PSU = PSU running; PSU+Pump = PSU not running (Leaktest w/ ext. PSU)

[Homeman]

Hey Stranger! After researching for 6 Hours straight with no success... I need your help

Used equipment in this scenario:
PSU: Thermaltake 630W, Corsair SF750
Cables: Generic 4-pin Molex Cable
Pump: Standard Alphacool D5 Pump
Tool to short the circuit: Paperclip

I am currently trying to leaktest my custom loop by connecting 2 pins of the D5 pump to an external psu and...
here is the issue:

The PSU itself (no devices connected) runs fine when I short the circuit with a paper clip.
The molex power wires give me 5v and 12v on my multimeter. So the PSU seems to be ok.

Now what boggles my mind:
I connect the red and the black pin of the D5 pump into the psu 4-pin molex (tried 5V and 12V) and turn the PSU back on... nothing.
The PSU is not powering and the psu power cables show 0V on my multimeter.
The connection of the PSU and D5 Pump leads to the PSU not giving any power. And I can replicate the issue: When I disconnect the pump, the PSU, when turning the switch back on, seems to run fine, no problems.

What am I overlooking here, am I really that stupid to run a leaktest?

I very much appreciate your time

 

[Ralston18]

9 volts?

I would not expect that...

FYI:

https://www.lifewire.com/molex-4-pin-peripheral-power-connector-pinout-2624582

List Molex pins, wire colors, and voltages.

This PSU?

https://www.amazon.com/ThermalTake-SMART-MODULAR-MANAGEMENT-SPS-630MPCBEU/dp/B00BDBZH3A

You mentioned external PSU - is there also an internal PSU?

If you have used any modular power cables from other make and model PSUs then that could be part of the problem.

Try to diagram out the connections and pins from source (external PSU) to pump.

I recommend discontinuing all further attempts to make the connection(s) until the proper connections and pins can be worked out and proven safe.

You may be one wire/pin away from things not ending well......

 

[Homeman]

Thank you for sharing ideas and concerns.

I got 2 external PSUs available to use for leak testing. I got "Corsair SF750 W" and "ThermalTake Smart Modular 630W" -> https://www.amazon.com/ThermalTake-SMART-MODULAR-MANAGEMENT-SPS-630MPCBEU/dp/B00BDBZH3A.

The internal PSU(V1100 SFX Cooler Master) is currently connected to all the other components in the computer system.

I have no original power cables of the ThermalTake 630W left. I use the power cables of the Corsair SF750 W or the power cables of the V1100 SFX Cooler Master.

At the moment I sadly have no colors on any wire except the wires that go out of the pump - which are 2 loose pins (red & black)

Voltages of Corsair SF750 molex power cables and the pump's outgoing wires:

https://imgur.com/a/GLlTCtE

 

[DSzymborski]

Ummm, modular power cables are not universal. Anything using a modular cable from the wrong PSU has a high risk of being fried unless you know for a *fact* that the pinouts on the PSU side are identical.

 

[Homeman]

Ummm, modular power cables are not universal. Anything using a modular cable from the wrong PSU has a high risk of being fried unless you know for a *fact* that the pinouts on the PSU side are identical.

I understand. Now the Corsair psu has its original power cables attached, hence the layout and everything should be OK. On the images I provided, the corsair psu has it's original cable attached and gives 12V. How do I know if I fried anything?

 

[Ralston18]

My concern is that using modular power cables from different PSU's may be the source of the problem.

12 volts - 3 volts = 9 volts.

Sketch out some wiring diagrams/connections that may reveal how that 9 volt measurement may be coming about.

On the molex connectors determine there is a pin to pin correspondence: Pin 1 to Pin 1, Pin 2 to Pin 2, etc..

Verify that the pinouts are correct before connecting anything.

 

[Homeman]

My concern is that using modular power cables from different PSU's may be the source of the problem.

12 volts - 3 volts = 9 volts.

Sketch out some wiring diagrams/connections that may reveal how that 9 volt measurement may be coming about.

On the molex connectors determine there is a pin to pin correspondence: Pin 1 to Pin 1, Pin 2 to Pin 2, etc..

Verify that the pinouts are correct before connecting anything.

It is Type 4 if that is what you mean? The 9 volt measurement came out on the ThermalTake 630W and not on the Corsair Psu.

 

[Ralston18]

9 volts being out of tolerance - correct?

FYI:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Take a look at the tolerances.

https://www.lifewire.com/power-supply-voltage-tolerances-2624583

 

[Homeman]

9 volts being out of tolerance - correct?

FYI:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Take a look at the tolerances.

https://www.lifewire.com/power-supply-voltage-tolerances-2624583

Thank you, these resources seem to be very informative for this topic.

 

[Homeman]

The thing is, previously this pump was connected to this exact PSU (Corsair SF750) and fully integrated into the PC system. I recently bought a stronger psu (V1100 Cooler Master), aiming for system stability because my system was running on insufficient power supply. The pump at that time (2 weeks ago) was always running, except for the increasingly frequent system failures I had - the pump was audible and running with the corsair psu. Now, my plan was to use the corsair psu as an external psu to test my loop for leaks. I am not sure what i am doing wrong (besides not knowing enough about tolerances and repair safety yet)

 

[Homeman]

9 volts being out of tolerance - correct?
FYI:

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Take a look at the tolerances.

https://www.lifewire.com/power-supply-voltage-tolerances-2624583

_______________________


The pinout is kind of weird. Idk if I am just dumb for not knowing that, but the pinout is mirrored and rotated by -180° if I look at the 24-pin motherboard side frontview:

https://imgur.com/a/sTvhbgf

I tested the 24-pin entirely. All values are perfect. The maximum deviation is lower than 0.5% if we compare it to the reference pinout diagram below:

 

[Homeman]

Well, I got impatient and connected the pump to my internal psu. The pump was pumping faster than ever and also… there was a leak on a tube connection, . Why is the pump not working with jump started psu? I just ordered a leak tester that uses air to test the loop, i am sick of this.

 

[Ralston18]

Could be 12 - 3 = 9

or 3 x 3 = "9"

The 3 being or should be 3.3v

If a 9 volt reading is still being measured then you need to draft out a schematic of all wires, connectors, and pins.

And, after reading back, what is the underlying reason for using an External PSU to test for leaks?

Remove the external PSU completely. Does the 9 volt reading change?

 

[Homeman]

Could be 12 - 3 = 9

or 3 x 3 = "9"

The 3 being or should be 3.3v

If a 9 volt reading is still being measured then you need to draft out a schematic of all wires, connectors, and pins.

And, after reading back, what is the underlying reason for using an External PSU to test for leaks?

Remove the external PSU completely. Does the 9 volt reading change?

there is no 9 volt reading at all for the Corsair SF750.
The 9 volt reading was from the ThermalTake Psu that had the wrong molex wire attached.

Question: Why is my pump working when connected to a psu that is not jump-started, but is not turning on with a jump-started psu?

 

[Ralston18]

Some devices are started by a switch that provides power when switch is closed = ON. And power is stopped when the switch is OFF.

Other devices are started in a more complicated manner that begins with a brief electrical connection (e.g. a push button) that, in turn, initiates some circuitry that results in the device being ON. However, a second press of the push button does not turn off the device. Powering off is done in some other manner.

That all said, if at some point there was a "wrong molex wire attached" then who knows what may have happened as a result with regards to the circuitry involved.

Exactly how were the original connections and any following connection made?

What pins in what connectors were used to "jump start".

My thought is that something was damaged during the testing process.

Especially if both PSUs were connected at the same time -

You need to sketch out some diagams showing all wires, connectors, and pins. PSUs, pump, fans....

 

[Homeman]

Some devices are started by a switch that provides power when switch is closed = ON. And power is stopped when the switch is OFF.

Other devices are started in a more complicated manner that begins with a brief electrical connection (e.g. a push button) that, in turn, initiates some circuitry that results in the device being ON. However, a second press of the push button does not turn off the device. Powering off is done in some other manner.

That all said, if at some point there was a "wrong molex wire attached" then who knows what may have happened as a result with regards to the circuitry involved.

Exactly how were the original connections and any following connection made?

What pins in what connectors were used to "jump start".

My thought is that something was damaged during the testing process.

Especially if both PSUs were connected at the same time -

You need to sketch out some diagams showing all wires, connectors, and pins. PSUs, pump, fans..

I understand. The situation might be more complicated...