Lesson CHEAP CHINESE MONSTER MOTO CLONES AND PROBLEMS

In all I think @OZHEAT does not understand what this site is all about. Sure if I was building a sim with a commercial budget, I would not be using cheap MM and DC motors. Ideally I would use AC Servo motors and matching controller/drivers - off the shelf - easy, but unfortunately not within my hobby budget. Making this stuff work, where all the 'Experts' said it was not possible, is also a personal challenge .

So a little further investigation I have found how ST can trace the chips with the codes.



So lets look at this chip



So we can see from these chips they were assembled at 99 "Muar" and the 3 digit lot number is "03U"

Country of origin MYS is "Malaysia" and the test site 99 was "Muar".

Now this is where I'm kinda lost, the year says "1" which I presume would be 2011 not 2001 however the chip didn't start manufacturing until 2013 that I can gather.

The week number is "14" which makes sense.


Now am I just being dumb or have I missed something so simple ??

I think you have it right except the chip started manufacturing around 2004.

Ahh nice work @BlazinH, I was just going from the date of the last datasheet. So they did manufacture the one above in 2011 which would make sense, however it was sat around for 4 years until it got into my hands.

@SeatTime Don't really know how to reply to this.
l'm all for diy on a budget, hell i'd rather build my own if I can.
Use a cheap motor driver like the MM but use it within it's capabilities.
hmmm, according to you SeatTime with 40 years experience in the field, you are the expert!

l'd assume that these cheapest MMs were originally from a run of boards for sparkfun but tested faulty or couldn't achieve higher currents without overheating, so they flogged them of real cheap on ebay rather than reworking them..

Soon enough, they found they had a high demand for them and did specific runs for ebay sellers printing anything except sparfun on the back but didn't test them at all relying on chinese QC (that means to me that QC is done by the end user complaining it was not working).

When you complain to the ebay seller they would say it works and it must be your fault, you post a vid for the seller and they concede that it is faulty and you can send it back for a replacement.

Now you think to yourself that postage back to china is going to cost too much and just forget about it.

You fine a different ebay seller and buy more, with a few extra just in case of faulty ones.

The sellers finally cotton on that the faulty ones aren't being ultimately being sent back and instead buying even more and to satisfy demand ask the manufacturer to increase supply, even if they are faulty.
The manufacturer thinks to himself, hmmm what if I start cutting corners to save money because ebay sellers don't pay as much as sparkfun, what can I do?

How about using less solder paste under the chip's heat pads or alter the time in the reflow oven as this will allow more to be produced in the same time or freeing the oven for other tasks. Reliability isn't an important quality for these batches, quantity is.

This works for a while and they sell heaps but they aren't getting as much complaints as they thought they would. Maybe many users aren't using them in high demand applications.

The sellers go back and discuss it with the manufacturer and ask for higher fault rate.

The manufacturer says we tried to have a reasonable fault rate, only other thing we can do is apply too much solder paste in some areas by making solder stencil larger in a few places but that will create shorts.

The sellers say go ahead and do that, which is now the products you now receive.


So what conclusions do I come up with?
1- people will accept a high fault rate for MMs and just buy extra.
2- this high fault rate is a good business strategy for manufacturer and sellers, how many would you buy if they all worked flawlessly?
3- it is not faulty vnh2sp30 chips but faulty manufacturing.
4- like a lot of chinese/indian products the quality is pretty bad but they sell, we all complain about it, but we still buy them!!! Who is to blame?
5- l do consider a lot of asian products a kit of parts which works a lot better if you disassemble and reassemble/remake with the care.
6- if you want reliability out of the packet buy them from sparkfun or pololu.
7- If you want cheap buy from ebay, expect to have to rework the board.
8- some people are so pig headed, I'd say that they were like a horse with blinkers on.


SilentChill, your up next....

Hah @OZHEAT I have to agree with most of what you say there your making sense. rather than talking data sheet crap

I was going to post something similar to what you have said there.

I have removed alot of the chips and I have reflowed them myself seems around 240-250 degrees is just about right for me. I have removed solder and added solder which ever the chips need.

I also have run the iron over the pins too to make sure they are all nicely joined. pain in the arse but seems I'm getting somwhere.

I have to disagree that the chips aren't faulty as I have quite a few which just short internally or don't put full power through 1 way replace the chip and the board works fine.

I've found some with no solder at all under some pins and on the heat slugs. the quality is just terrible on some of them and it does seem like they are done on purpose sometimes.

I have now added heatsinks to the bottom of the boards aswell as on the top of the chips. try and get rid of a few more degrees.

I forgot to mention some of the soder they use is shite some breaks away into micro balls and then floats around the board until it nicely shirts something out.

So now I use a toothbrush and alcohol to get rid of them

@SilentChill I watched your youtube video on testing the MMs.
While I don't deny that they are faulty, you diagnoses are flawed.

you said your power supply outputs 12.15v dc
Your say "good" with a output voltage reading of >12v and "a bit low" @~11.8v
This is wrong, if your getting >12v I can safely assume the low side is shorted to ground and is faulty.
l would say about 11.7v would be about the correct output.
In a correctly working half bridge you will never get full power supply voltage due to resistance of the bridge circuit, which includes the resistance of the mosfets(RdsOn) and the current sense resistor.
Your >12v s means shorted to ground on the low side bypassing the current sense resistor, hence a low voltage drop.
Your zero volt output indicates high side is grounded which would be the reverse of the 12v output.
You can confirm what outputs are shorted by using your multimeter, there should be no continuity between ground or +ve to any outputs when not powered.
When you apply a motor load to the outputs and you say "Slow" I suspect that the chips protection is shutting down the chip, the only problem is that because the configuration your using the pwm input and that resets the chip protection every 3-4 cycles. Hence it acts a bit like pwm but not variable pulse width, it acts with missing pulses.
Why don't you put your multimeter across the motor terminals?

thats about it, if you want to know how i'd be going about testing let me know...but it won't be tonight, I've spent enough time typing tonight.

Not trying to bag you guys, just trying to help you guys.

PS. Seeing that you didn't like me not actually used a MM, I have ordered 3 to try out but you probably know that will be around a month to get here.

Oh I forgot, I did look at the board layout and put arrows at high potential locations of the board where shorts could occur.

hmmm, pic didn't post and I can't find the upload button editing my last post.

@OZHEAT I did put the multimeter across the motor terminals. that's my whole point in the video, the voltage is ok I would say anything below 11v would be shite but when you are getting above 11v on the multimeternal you think yeah that's great but as soon as you put load on the chip it shorts out internally it's not the board it's the chip the chip I say the chip the chip is faulty when it does that I can't say enough times the chip is faulty

The power supply out puts 12.85v or something like so your looking into pick at nothing the test works to show that the board or the chips if fecked.

I am not an electronics expert as you may gather but I just did the video to show the people I bought the MM's off and for everyone else to test, it's not to perfection or to the exact millivolt or whatever.

Your suspicions are yet again flawed by believing in what your reading and having no practical experience with the chips.

Stay away from the text book when you get your MM's

Sorry your shorting points are wrong as the traces run under the board they are not open to contact. I will take a picture for you here



So again because you don't know what ya talking about your wrong.

Also different boards have different designs and traces so not all are the same.

I know your trying to help but seriously stop trying to catch me out.

@OZHEAT Good to hear that you have purchased some electronic components - your real learning starts now.
FI - Some of my old findings in actually investigating faulty MMs are below:

First image shows how the main pads on the driver chips had not even been flow soldered - looked fine from the outside.




Second image shows a different board and how some of the chips had not even been placed properly on the board.
Repaired - it then worked perfectly. Believe me I too looked for a different solution due to the suspect quality control of these boards, but it still turned out cheaper for me to swap out serviceable chips from other boards and I did have a better run of serviceable MMs than @SilentChill. As I have stated before, If you don't have the expertise to change out the chips then I would go the Sabertooth route. More money, but likely less hair pulling for the less technically experienced. Although one thing that I do not like about the Sabertooth driver is that I cannot easily tap into the control signals which I use to feed my actuator limit switches.

@SilentChill , A H-bridge is a H-bridge. basically just transistors aka switches and something that drives the switches.
Doesn't really matter if it is integrated in a single chip or done by separate components on a board, symptoms of faults will be similar.
Yes, a MM has some added "features" such as shutdown protection and current sensing.

I will leave you alone.
You seem content in your ways, maybe you'll reach your century soon. gl

No Im not content at all quite the opposite but I have proof of what's wrong you have nothing at all.

You have contradicted yourself about the boards and chips possibly being b grades from sparkfun. which is what I was saying in the beginning.

So yes leave this thread be and when you have some evidence of your own please come back and share your findings other than theories and hypothesis

Where oh where did I say b-grade chips?
Go ahead a keep torturing your boards, just to prove they are faulty?

This is for anyone who would like to test their Motor monster "clones".
It is no secret that the fault rate of these h-bridges is very high.
Expect to have to rework the board.

This is a some things of what I would do, hopefully you will adopt some or all.

1- Fresh out of the packet before connecting any wires inspect the board. the most low level test is using your multimeter on continuity/buzzer setting.
Test each output A1, A2,B1 & B2 with VCC(positve supply), board ground( top layer) & switched ground(available near each output).
There should be No continuity between any of them, if you do, you got a short.
2- If your satisfied your ok, next would be to take baby steps in power testing.
A small low power dc motor or maybe a car taillight globe for a load.
For motor power supply, either 5 or 6 AA batteries in series or a light globe between your power supply and VCC, this is so you limit current to the board. You don't wan't to put whatever amps you power supply can handle through a short unless you are intending on sending it back to seller.
3- The board provides some "features" namely Current Sense (cs1 & cs2) en/diag, use them. If you look for add ardinio libraries search vnh, it will display vnh5019 by pololu. Besides 1 extra pin that the vnh2sp30 doesn't have (cs disable) they are very similar. The demo.ino will ramp each motor back and forth, monitor average current and tell you when a fault is detected reporting to the ard com port. Hopefully someone can expand on the fault report by displaying the states of the different pins instead of just "motor1 fault".

cbfa ....

if it tests early on in your testing, rework it. Don't keep going and torture it just to prove it is faulty. maybe a few more chips will survive.

@OZHEAT

OK @OZHEAT I had 6 more MM's arrive yesterday and in total 1 board fully worked and the other 5 only one chip out of 10 worked in both directions. There were no shorts on the boards everything checked out as soon as power connected everything checks out ok forward and reverse LED's nice and bright, connect a motor and it shorts out either not working at all or just driving the motor very slowly and the chips overheat incredibly quickly.

Explain that to me if they are not faulty chips ????

@SilentChill that seems not to be good at all... but as i read you have new powerful babies in your hands...

i think the days of MM are at their end for motion. they should be used for wind only as you said before although i am going to try them first in my next build.

you are the one who has bought the most MM here and guess from different sellers too.
could you post the sellers with the faulty ones so people avoid them?