Photos Part Three: Dissection and Inspection
If you’ve read previous reviews you’re probably begun to suspect that I like taking things apart. It’s true, I do. Because of that, I took the Water 2.0 Extreme apart too. I left the actual pump in one piece because it’s the same as the others, but the PCB is different so the lid had to come off!
Here we have the guts of the thing. A brushless, conless, motor, a couple active ICs, some filter caps and a few other passive parts.
This is a fairly standard pump/fan controller for running this sort of motor. Nothing special here.
This however has some brainpower, it’s a microcontroller from SiLabs. Unfortunately because it’s a microcontroller with custom code on it looking at a datasheet doesn’t tell us much about it. The code is the important stuff and even if I pulled it off with my Bus Pirate it would be, at best, assembly. In any case, this character talks to the software via USB and spits out a PWM signal to the fans. We’ll look at that PWM signal momentarily. Scattered around and about is some mildly dubious soldering, but nothing that’ll cause issues.
Here we have the PWM signal on the scope, the scope is set to 20 microseconds / 2 volts.
First we have at full low speed:
If you don’t know how PWM works, here’s the short version: The more time the line is up top, the faster the fans go. In this case the signal is switching on and off at about 24.6kHz and the signal is high (up top, looks like 3.3v) for ~6 microseconds, this gives us a PWM duty cycle of about 14%. Next up, roughly 50%:
Equal time high and low, roughly 50% fan speed.
At very nearly full speed the line is, of course, mostly high. At full speed it simply stays high the whole time.
In all cases this is a very clean signal, it looks quite good.
