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new board, strange motor behaviour

Posted by blabberjack 
new board, strange motor behaviour
September 25, 2015 01:00PM
Hello, I recently fried my Ramps Controller, I was doing a long print overnight, I woke up quite late and decided to go and check on the machine, the feed had blocked, no big deal, it happens sometime. My ramps controller is in a nest of wires though so to terminate the print I usually flip the socket instead of pressing the reset, I have to switch it off and then back off so that the fans keep running to cool down the hotend and keep the blockage from getting worse. Anyway I switched it on and off a little too quickly and shorted my 12v supply. Luckily I had another one on hand, unluckily I am a total moron and in my sleepy stupor I got the + and - mixed up and fried the board.
So I ordered another board, just the top part, the original arduino is still in use and hooked it up today. The endstops and SD card are working fine as well as the bed and hotend heaters and thermistors however the motors make a huge ammount of noise and don't really get moving at all (X and Z move a little, Y stutters back and forth, though I may have gotten the wires mixed up on the Y, the other two are 4pin plugs the Y is mashed together from jumper pins). The drivers are from the original top board.
Do I need to replace all my stepper drivers or could it be that my arduino is slightly fried and needs replacing?

Fried board with reversed polarity, replaced shield board, motors not working everything else fine- replace arduino/replace stepper drivers or what?

Thanks for reading : )
Re: new board, strange motor behaviour
September 26, 2015 12:35AM
You can't 'short' a supply by power cycling . . . a short is an errant electrical connection. Some supplies will 'crowbar' (go into protect) from this, and simply leaving it unpowered for a while may bring it back to life. If not, check it for blown fuses.

- Tim
Re: new board, strange motor behaviour
September 26, 2015 04:26AM
I´d put my money on the stepper drivers, they are easy to break. The arduino OTOH has a reverse polarity protection AFAIK.
Re: new board, strange motor behaviour
October 15, 2015 07:37AM
Sorry for the delay, I had to wait for drivers to be delivered. I have them installed now but actually the board appears to be more broken now, motors now don't respond at all and the termperature probes are reading between 2 and 10C which is much colder than it really is, they also don't respond to when I heat the hotend/bed. endstops are still responding.
I got the DRV8825, haven't used them before but I don't see how they could be responsible for this malfunction.
try the arduino?

*Bed and extruder are now responding, so everything but motors despite the replacement drivers. Could having faulty drivers in place before have damaged the working drivers?*

**had a look at the pins on the new drivers and realised I had put them in backwards! I just assumed that the little pot would be facing the same way, silly me. I stuck them back in the right way and got the result I talked about in my first post: lots of noise, no movement.
Luckily I bought five drivers and only installed four so I was able to put in a single new driver that hadn't been installed backwards to test and it gave the same result so I don't think the problem is the drivers.
Also curious note when the drivers were turned the right way around again, the temperature readings returned to normal, weird eh?
what do you think I should do next, I have the single driver that I know (probably) work, am I best just replacing the whole shebang?**

Edited 2 time(s). Last edit at 10/15/2015 08:08AM by blabberjack.
Re: new board, strange motor behaviour
November 02, 2015 01:47PM
Hello again, I went ahead and replaced the whole board, arduino, ramps and drivers this time just with standard pololus took a while for it to be delivered.

I've now got two of the motors moving smoothly, everything else working fine; endstops, heaters, thermistors etc.

what is happening now is that when the x,y and z motor leads are plugged in, at least one motor moves erratically.
with only Y&Z plugged in, those motors move smoothly.
I moved the X pins over to the E1 and now the Y motor moves erratically.
If I switch the motors around, the problem moves between motors, so the 'X' is always erratic when Y&Z are also plugged in, 'Y' is erratic if E1 and Z are in.

I'm really at my wit's end here, the only thing I can think is that my power supply is somehow insufficient, I'm using a 12V, 10A supply though its quite a cheap one. Is this possible?
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