Replacing DOA Chinese 3020, 6040, 6090 style CNC Router Electronics – Introduction have now replaced or supplied replacement electronics for around 100+ 3020, 6040, 6090, and other Chinese eBay routers with Dead on Arrival (DOA) Electronics.

It does not appear to be slowing down and so instead of helping on a one on one basis, we will now write up each repair/replacement so that eventually we have a list of the issues and fixes for each of the models.

eBay has no interest to discuss the problems or kick off the sellers as they know it would open up a can of worms for themselves to start assessing items for suitability and safety – they would also lose a lot of revenue, they make 10% of the cost of the sale including on shipping. Between $60 and $200 from each broken and dangerous CNC machine, they facilitate the sale of.

We should stop here and say: “3Dtek are not saying you should not buy these items and does also not believe that all of the sellers of these items are as bad as each other.  Simply do your research, be ready to make some modifications, as well as some make safe.”

None of the retrofit work we have done to date has been documented however we are tired of fixing these things and so have decided to write up each retrofit, they will have their own posts and a link to each one will be at the bottom of this page.  If you have a router with different electronics and need to fix it we can sell you the parts, & help you with the information in exchange for some photos to enable us to create a new write up for that model.

Background on the issues:

  • Generally, these 3020,6040, and 6090 style machines are mechanically OK, however, the electronics are both unsafe and unfit for use in Australia as well as being DOA or shortly after. 
  • If the electronics do work they generally require a parallel port which is difficult as you need an on-motherboard board parallel port, not a USB dongle and not most PCI cards which will unfortunately not work – don’t even try – they may appear to work but not when you actually go to do the job.     
    • The USB dongles and many PCI cards use software flow control for data transfer which is sort of like a long distance call used to be where you would speak the words and they turned up at the other end of the line turns up eventually – clearly, we need more precise timing in CNC.
    • This solution also requires a 32-bit version of windows from the Windows XP era which is difficult to find a keep alive, as well as a cracked copy of Mach3 which is unacceptable.
  • Some alternative packages are supplied with a rip-off Planet CNC USB controller which does not work and is understandably not supported by planet CNC. Further most eBay specials are advertised as, however, come with either a Parallel port or parallel to USB dongle which we have identified do not work and cause only frustration.
  • To date, we have not seen a Chinese machine with any Earth connections to the earth pins on the Power Supply Units PSU(s).  
  • Those that do have chassis earthing are generally earthed to a painted frame and without star washers.  The PSU’s are bolted to the frame so have a poor earth connection of sorts, however, to save $0.50 on an earth wire to the detriment of end-user safety is a bit of a sin.
  • Several of the units we have found to have active and neutral reversed on one or more of the internal PSU(s).
  • Many have used 350W power supplies to power 400W spindles.
  • All of the power supplies have not been approved and are not fit for use in Australia
  • Similar Story for all of the single to 3 Phase VFD units.
  • All of the 3 Phase spindles have an Earth pin on the plug, none have actually been earthed
  • None of the 3 Phase spindles had been wired using a cable of appropriate shielding, insulation break down protection, current carrying capacity etc.

The list goes on but these are the main issues that seem to plague 99% of the Chinese machines.

Are you worried now that there is a death trap in your garage?   We are not saying they are death traps, just that little to no concern for best practise or safety has been applied to the design of this machine and so treat it with some suspicion. Don’t leave it plugged in, don’t leave it unattended, don’t let your kids at it and why not ask an electrician to spend an hour fixing the little issues with the PSU’s and grounding so you can breath easy.


If you purchased the item from any source other than an Australian Business with ABN then you are likely considered the importer of the machine and as such retain responsibility for the device and any harm it creates, where ever it goes.  What this means is that if you on-sell the device you really should have the power supplies and VFD (if it has one) replaced with acceptable Australian approved parts and also have the other non conforming wiring bought up to Australian Standards before moving it along.

Or.. Better yet get it fixed an use it!


China CNC Episode 1: Bobs 3020 + 300W Spindle & Mini CNC Controller