VPP755 Loses a lot of pressure

[JPincho]

Hi there. I've bought an entire circuit last year include a VPP755 with reservoir. For some reason, when I power on, everything seems ok, I can see the water flowing back to the reservoir with a decent pressure, but after a couple of seconds, it goes down to almost a drip. I tried unplugging the PWM and leaving only the molex, and changing the dial on the bottom to 4. Nothing changed. I added more distilled water, in case that would be the cause, but still no change.
Is this normal? It doesn't feel like it.

 

[Eddy]

No, this is not normal. Are you reading the speed of the pump? If so, does it change at the moment when the flow decreases?
If the speed is constant, then the problem lies elsewhere. If you are using hoses, check them. When the system has been running for a while, the water warms up, so the hoses become softer and bend further in tight places, which can hinder the flow and even cause it to break off completely.
If you don't use any hoses, then I would rather assume that there is dirt somewhere in the system. And the dirt then sits in front of the channels in the radiators, for example, and partially blocks them, or something has got in front of or into the nozzle fins of the CPU or GPU cooler. When the water is at a standstill, the dirt may fall back, so that you first have a good flow at the start of the system before the dirt pushes in front of it again and obstructs it again.

 

[Shordy87]

Hi,

i had a similar problem. After a short time there was almost no flow in the reservoir. but the temparatures and pump speed was fine. I then left the lid of the reservoir open for a few minutes while the pc was running and the problem was gone. Maybe it will help with you

 

[JPincho]

I am not reading the speed. How can I do that? I know I'd have to connect it back to PWM, and then what?
This is all a brand new system, It did this from the beginning. I am using maleable tubing, but all of them are in straight lines.
I tried a few more things. Back in BIOS ( or setup, or whatever it is called now ), I changed the mode for cpu fan and chassis fan 2 from temperature dependent to full power. Both fans really started blowing hard and making a lot more noise, as expected.
If I connect the pump's pwm cable ( that is not actually a PWM from what I've read, still voltage based ) to those slots, nothing changes. Either in PWM or voltage mode.
So I tried messing with the definitions for the AIO slot ( where the pump was connected ) and still nothing changed.
I unplugged the power molex to the pump, it obviously died, and as soon as I plugged it back in, it went full power for a couple of seconds and then back to the drip drip drip. This was all done with the system on, so I could test if it was some different voltage supplied to the Motherboard during boot, or something.
Then, to check out the possible dirt problem, I closed the loop with only the pump. Nothing changes. One single tube coming out from the pump and back into the pump does exactly the same thing.
I don't get it.

 

[JPincho]

Hi,

i had a similar problem. After a short time there was almost no flow in the reservoir. but the temparatures and pump speed was fine. I then left the lid of the reservoir open for a few minutes while the pc was running and the problem was gone. Maybe it will help with you

I am now running with the reservoir open, and still the same. Did not work for me..

 

[JPincho]

I just noticed the GIF I had uploaded was rejected for being too large. I recorded the pump's action again, so I'll upload it here.
On the second time, I unplug the molex for the pump while the system is running, and immediately plug it back in, so the water doesn't even have time to settle. It does go full speed for a few seconds and then back down. Also, with the reservoir lid open ( Obviously I now see a lot less moisture in the reservoir. I guess the water not running at its desired speed makes it not cool decently in the radiators )
Also, I just noticed that the time the pump spends in full power is always exactly 10 seconds. It drains the radiator pretty quickly, all seems good, and then 10 seconds later, gets really slow.

I cannot attach the full video, here's a link to it on google drive.

VID_20210226_132643.mp4

drive.google.com

EDIT:
I can't get any readings from the pump, no matter where I plug it into. in BIOS, it always says N/A. I'd guess the PWM module is dead, but then again, if I inplug that cable, it should just run full power from the Molex, right?

 

[Eddy]

Ok, I'm a bit confused by all the explanations because I can't quite understand some of it. Therefore, please only answer the following things so that we can get some structure into these discussions and I can follow you.

1. The 4-pin Molex connector is plugged directly into the power supply unit. Correct?
2. Please plug the 4-pin PWM connector into CHA3 FAN. Then set it to PWM in the BIOS and push the fan curve there completely up to 100%. On your second screenshot you can see the fan curve with the line and the white dots. Everything must be pushed all the way up.
3. At the bottom of the pump, there is a small black dial. There are also numbers around it. Please set it to the highest number. Below is a picture of what it should look like.

And now restart the computer and tell me what happens.

 

[JPincho]

That is almost exactly what I did.

1. The 4-pin Molex connector is plugged directly into the power supply unit. Correct?

Correct.

2. Please plug the 4-pin PWM connector into CHA3 FAN. Then set it to PWM in the BIOS and push the fan curve there completely up to 100%. On your second screenshot you can see the fan curve with the line and the white dots. Everything must be pushed all the way up.

Back in BIOS, I changed the mode for cpu fan and chassis fan 2 from temperature dependent to full power. Both fans really started blowing hard and making a lot more noise, as expected. If I connect the pump's pwm cable ( ... ) to those slots, nothing changes. Either in PWM or voltage mode.

The difference was that I plugged it into chassis fan 2 because it's closer. For some reason chassis fan 3 is on the other side of the motherboard. I can control a fan with it, change its speed, read back its speed, so the connector is ok. When plugging the pump, tried setting the control for that connector in PWM, full cycle and the end result says nothing. The pump goes down in power after 10 seconds, and I can't read any value from it.

3. At the bottom of the pump, there is a small black dial. There are also numbers around it. Please set it to the highest number. Below is a picture of what it should look like.

It is currently at 5. I had assumed the open part of the notch to be "forward", but from your picture it seems it's the other side. I corrected it, and nothing has changed.
In BIOS, I set it to full duty cycle, nothing happened. set it to off, no cycle at all, nothing happened. It seems the pump is completely ignoring the PWM input.

From what I understood, the pump uses the measurement from PWM but never goes over the setting on the dial, so if no PWM is connected, by being connected to the PSU with the dial up to 5, it should be at max power, right? It doesn't.
Or maybe it thinks it's reading something wrong from the PWM connector, and that assumed value is very low, and limiting the power?

TL;DR
Nothing changed

 

[Eddy]

Well, easy... pump is defect. There is nothing more you can check, so please start an RMA. The pump does not respond to the PWM signal and it does not respond to manual control. Then you don't have to think any longer, there is nothing more you can do as an end customer.

 

[JPincho]

ok, this is going to sound stupid, but I cannot find the link for RMA in alphacool's website. Can you help me?

 

[Eddy]

Write an email with your order number or customer number to info@alphacool.com