Vectra M2 Thermisotor Error - FIXED!!

Joshevelle

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Hello R2R Community.

This will be my first post, I am usually a spectator, but since I could not find anything in the whole web related to this problem, I wanted to share this information with the community.

I have two Vectra pumps, M2 and L2. Two weeks ago, I heard water noises coming from my tank. The Vectra M2 was off, and its Quiet Drive was Flashing Red/Orange, I was able to connect via Mobius and there it was, "Thermistor Error".

Thermistor Error Vectra.jpg

Looking into the forums, meaning this community, I found that there are many other users that faced this very same problem.

The problem, according to Ecotech webpage is that a component inside the motor has gone bad, the solution they propose is to ship back the pump to them so they can either, fix it or send you another pump, of course if you are out of warranty, you would be charged for it.

I had only used this pump for no more than two months, the problem is that I bought it from a fellow reefer locally, he bought the pump brand new in California and it was too big for his tank (in Mexico), the pump was stored in his house for a bit more than a year, then I bought it from him. He is a close friend, so I know that is true.

We both live in Guadalajara, Mexico, so shipping the pump back is not an option for us. Only the shipping charges would be enough to buy another pump.

Long story short, out of warranty with a shiny almost new pump.

I tried everything, disassembly/clean the motor, clean the connectors, nothing helped. So, I was about to buy another pump, and decided to mess with the electronics of the Vectra M2. I am an electronics engineer, and the pump was already dead, I had nothing to lose.

My findings were really helpful for me.

There was nothing in the web regarding the guts of the Vectra, nothing, not a single connection pinout, circuit, tear down video, NOTHING. So, I went totally blind during the disassembly.

I started by taking measurements for the Vectra L2 that was working perfectly. Starting by the male connector coming from the motor, we have five connections, three are the BLDC motor (Brushless DC), and the other two are for the so called Thermistor, this is a device that constantly monitors the temperature inside the Vectra, this type of devices changes its electrical resistance (ohms) when they are exposed to thermal changes, this is how the Quiet Drive knows if the pump goes dry (it increases its temperature, drastically).

This is an easy fix if you are familiar with electronics, if you are not, and you have a dead Vectra with the same error, take it to any electronics repair shop and show them this thread, they will understand it.

This is the internal diagram of the Vectra, as well as the connection to the Quiet Drive:

Vectra Pump.jpg

From the pump side, we have the male connector. BLDC Motor are terminals A, B and C, Thermistor terminals are 1 and 2. While the Vectra L2 was working, I shut it off, and took the measurement for the Thermistor resistance, it was 30K ohms. The Vectra M2, was off for more than a week, the "cold" or off status measurement for the Thermistor was 64.5 ohms, which must be its value at 25C (water temperature), yes it was inside the sump the whole time.

This is the male connector from the pump:

Vectra Male Connector.jpg

This is the female connector from the Quiet Drive side (sorry for the blurry image):

Vectra Female Connectorf.jpg

I was tracking the problem by taking the measurements with all the Vectra M2 connections done, and the Quiet Drive PCB exposed. The problem was not in the motor, it was in the tiny cable going from the female connector in the Quiet Drive, to the PCB inside the Quiet Drive.

First you have to measure directly in the male connector going into the PCB board in the Quiet Drive, is the connector highlighted in green, sorry I did not take a picture while disconnected, but you have to press the upper tab and pull the connector:

Vectra Board to Cable.jpg

Open Cable Vectra.jpg

I tracked it down by measuring continuity and there was an error in the connection #1, that corresponds to the Thermistor, the Quiet Drive was sensing an "open" circuitry in the Thermistor, hence the error message was Thermistor Error. I fixed this by adding a "bridge", which is a small cable added to the gray cable.

Notice how the gray cable is already cut down, but it was not like that when I removed the black insulation material, the gray cable was in mint conditions, except it did not have electrical continuity. You would need a bit of experience to know where is the open circuit, but is not that hard, I use a multimeter and a small needle to pinch the cable.

After this fix, the pump has been running perfectly, no errors whatsoever.

The cause? well, I noticed that the two cables for the Thermistor are a smaller than the three cables for the BLDC motor (you can notice that in the picture). Mixing cable wires with different gauges inside the same cable is not a good idea, from the manufacturer's perspective, you could save a couple of cents per meter of cable, of course, cents adds up when you are buying kilometers of cable.... From the user point of view, you are paying a bunch of money for a top-quality product that, apparently, is failing in the field.

The natural bends in the external cable during the installation, stress up the inside wires, the two cables corresponding to the Thermistor are the most prompt to break because of the stress.

Summary: if you have a Vectra pump with a Thermistor Error and you are out of warranty, start by measuring continuity using a multi meter, disassembly the Quiet Drive and make sure that the PCB has the corresponding measurements for the BLDC motor (A, B and C connections, shown in my notes) and the Thermistor (1 and 2). If it doesn't, track the open circuitry, chances are, you can fix your own pump.

sorry for the long thread, but I wanted to give as much information as possible, I couldn't find anything in the web, and I hope I can help a fellow reefer by posting this.

Saludos from Guadalajara Jalisco, Mexico.
Joshua Nuno _\m/
 
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Joshevelle

Joshevelle

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I'm a bit confused still. Are you bypassing the thermistor or are you simply repairing the open in the cable?
I did fix the gray cable.

DO NOT BYPASS THE THERMISTOR.

if you do that and for any reason your pump baffle goes dry (it has happened to me (ATO fail)), the QuietDrive would not know when the pump is over heating. Hence, a bypass thermistor means, a FIRE HAZARD.
 

Heres_doe_

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I did fix the gray cable.

DO NOT BYPASS THE THERMISTOR.

if you do that and for any reason your pump baffle goes dry (it has happened to me (ATO fail)), the QuietDrive would not know when the pump is over heating. Hence, a bypass thermistor means, a FIRE HAZARD.
Will this be the same for a m1? How does the body open up as well?
 

reefinaglassbox

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My L2 stopped last night throwing thermistor error on the mobius app. When the pump stopped there was no push notification on my mobile from the mobius app.
What's happening with these pump is the thermistor within the pump is failing or in some case the wire is broken which OP reported here , in my case it's more of thermistor failure . Essentially the controller is not getting any resistance reading and has becomes a open circuit

IMG_5774.jpeg


Vectra.jpg


I am not sure whether it's a NTC or PTC type thermistor, probably it's NTC. Now to keep the controller happy and by providing a resistance in acceptable range I soldered a 100 K E resistor between the terminal shown with arrow in the image . The pump is back in action now.
The stuff which I don't understand is why ecotech put this thermistor in the controller equation probably for shutting down the pump when it's outside operating temperature limit.
You can still achieve that but plugging in the Vectra power supply to a temperature controller and fixing the Ink bird/ similar temp controller sensor to pump body.
Looks like ecotech needs to change the pump design and take out the thermistor external to the pump, when a pump operating 24/ 7 on a saltwater environment it's a recipe for failure .
 
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