Originally shared by Marcus Wolschon
Bad news.
After the test-cuts yesterday I wanted to do the first real jobs on the TravelCNC (http://marcuswolschon.blogspot.de/2013/07/travel-cnc3d-printervector-cutter.html)
…and when I switched on the power supply my X-axis stepper driver vaposized in a big pile of smoke.
Stepper works fine, all other 3 axis work fine.
Power connection to the blown stepper driver is fine too.
So sorry. I hope you find what caused this problem & replacement part soon.
yes.
4 of the better chips including shipping cost as much as one of the drivers. 
I’m currently milling with the Y axis connected to the A driver to continue my tests.
It seems that at least all lost steps are not completely gone.
Yes, AliExpress.
a FMD2740A from “Thomas Wu”.
I just noticed.
In the description the write
"Power supply voltage 12 to 50VDC "
but in their graphics it becomes 12-40VDC
AliExpress has an interesting rating system.
Before me there here 4x 5star ratings.
I rated 1 of 5 stars. Now it lists:
“Item as Described: 4.9 Above Average”
Shouldn’t that be “4.0” and nothing about any average?
Never again from china, not to cnc. On drive board from them I had 700mm/min. And mising steps, I get drive board from Poland, and I have 10000mm/mm on the same contstruction
No, this is Polish production.
What board is it and how many Amps?
The chinese are offering me to send it in (lol, from here to HK that cost s as much as the unit itself) and don’t say a word about the unsuitable parts I mentioned.
Electronics are never “landfill” they are hazardous waste and a lot of the more expensive materials used can be recycled.
Good news: on more lost steps, much improved speed and torque and the chinese dealer is even offering to pay for the repairs (I’ll only send it back to china when replacing that chip doesn’t work.
It’s simply too expensive and time consuming and getting a new one with the same underspeced chip won’t be a permanent solution.)
The original electronics of the YOOCNC/carving-cnc 3040 had a combined board that does spindle-VFD and power supply for the stepper drivers.
So you can imagine how noisy the supply voltage to the steppers was.
on the rating system: (4x5star plus 1x1star)/5 ratings = 21/5=4.2 average. So they’re faking it, or doing some sort of weighted average.