A look inside a cheap chinese frequency converter

In this video I take a look inside the NFlixin nf-9000 inverter drive.
I got this for free and the warranty is gone since I drilled a hole in the heat sink for an earth connection. So, I’m willing to take a gamble and see what’s inside this cheap Chinese vfd.
Maybe I get lucky and somehow I fix the problem.

Want to support my video efforts, you could buy some shit through my Ebay and Banggood affiliated links below :)

some products I really like:

[Rolingmetal]

FYI: Without the sensor connected, F062 (heat sink temp) reads zero and rises rapidly when I short the connector the drive goes almost immediately into overheat protection. So the sensor most be an NTC and firmware seems to be programmed to start the fan immediately. (Perhaps to cool the build-in brake resistor)
Unless I find a parameter to change this behaviour, witch seems unlikely given the limited manual, there is not much I can do. Looks like the manufacturer was correct and the manual wrong. It still sucks though!

[whidbeyman]

Thie third wire on a 3 wire fan is usually a tachometer output. The CPU monitors the tacho signal and generates a fault if fan speed goes to zero with power applied. Fans speed is controlled by duty factor of power applied. Fan motors are nearly all brushless types, and a series resistor may or may not work. The goop on the heatsink is usually a grease filled with titanium dioxide to improve thermal conductivity. The 'condoms' are probably a composite of silicone resin and some sort of glass fiber or thermoset plastic mesh that improves its compressive strength. There is usually enough thermal grease left on the heatsink and components that reassembly is satisfactory. However, this assumes you didn't scrape it off and/or damage the 'condoms' during disassembly. You can use a 3 wire fan by just ignoring the tacho output wire. Just be sure to get the polarity of the other wires correct. Your drive fan is probably a 24 volt model. Computer fans will be 12V or 5V, so not useful. You should be able to order a quieter replacement fan from any electronics distributor. Presuming you are in Europe, maybe Farnell.

[dynoguy]

That sensor is most likely an NTC so it's measuring, not switching. Be careful when you re-assemble the IGBTs and the rectifier, good thermal contact to the heatsink is essential. Also make sure the insulation is not damaged and correctly in place as the IGBTs are at 320V against the heatsink. Mine is definitely quieter, but you can use one of these cheap temperature controlled PC fans. Or just unplug it, the controller will switch off when it gets too hot anyway.

[EducatingSavvas]

I wonder if the drive heats up during normal operation, and the the spindle is turned off - if the fan will remain on if the sensor detects the temperature is still over 45C?

[norbertpalkovic]

Good day, I bought a frequency converter FN-9000 220V 1, 5Kw. Some parameters eg. :F089 / F090 min / max for AL1, min frequency F016, AC volt F084 I cannot overwritten. I don't know why, I could ask you for help. Thank you for your reply.

[Xynudu]

Why not just replace the fan with a quiet one ?

It just looks like a PC case fan, and they are generally very quiet, and run continually.

Cheers Rob

[lv_woodturner]

I think the next step is to disconnect the fan. Your motor is smaller load than the 2.2 KW capacity. Likely the fan is not required. I would disconnect the fan and try again.

[davesmith]

Another great video. I really like your calm, understated style. keep them coming ;-) Thanks.

From what you said in the video and also the other comments about other fans and resistors I think you are on the right track already with this. But as 2 more alternatives :


2) May not be possible if your lathe motor has no fan, but if the motor has a fan, as a twist on the "since your load is small maybe you dont need a fan at all" approach .. the control panel can be mounted remote from the unit, mount the VFD so the airflow from the motors fan blows through the heatsink, and leave the VFD fan not running

good luck