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Author Topic: I probably killed my first machine ๐Ÿ™
zumselman
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Posts: 4
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Post I probably killed my first machine ๐Ÿ™
on: March 6, 2018, 14:02
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Hello,
my name is Jรผrgen from Germany - a few weeks ago I discovered v-plotters for the very first time and tried to build one on my own using the polargraph software - I succeeded and got some really nice results until my power-supply died (I ignored that it was too weak)

I run an arduino-uno clone
with a clone adafruit V1 motor-shield
2 NEMA 17 stepper motors
and my polargraph software is the most recent from 1 nov 17

I bought a new 12V DC 30A power supply that seems to work fine - my multimeter shows 12.03 volt and the old PC-Fan works properly.

The photo on top shows the last correct drawing which ended unexpected leaving the motors just making some high-frequency noises.

After setting the whole thing up again I got the drawing on the bottom with motors shaking and obviously not doing what they should do.

The Adafruit V1 motor-test is also not working properly, so it does not necessarily seem to be a software-problem.

Does anybody have a hint on how to find the error in my setup - which item should be replaced first to make it run again.

I would be so glad to get some help - maybe someone already experienced a similar behaviour of the hardware.

Kind regards,
Jรผrgen (zumselman)

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gamebox13
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Posts: 11
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Post Re: I probably killed my first machine ๐Ÿ™
on: March 6, 2018, 15:44
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Too much speed or too low current

zumselman
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Posts: 4
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Post Re: I probably killed my first machine ๐Ÿ™
on: March 6, 2018, 17:43
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Quote from gamebox13 on March 6, 2018, 15:44
Too much speed or too low current

Thank you for taking the time to reply to my problem gamebox13,
settings and current had not been changed since the incident.
After the regular Adafruit V1 Shield motor test did not work properly any more, i suspected the shield might have been deep-fried by the dying power supply - I checked the motors using my cnc-shield and they rotate as smoothly as before. Plugged into the V1-shield they refuse to react to the test-sketch in the desired manner

so my newbie mind thinks of two options
- the V1 shield does not like my new power supply (that seems to work perfectly with the CNC shield)
- the V1 shield is broken due to the broken power supply incident

I think I'll have to order a second V1 shield to find out

sandy
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Posts: 1317
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sandy
Post Re: I probably killed my first machine ๐Ÿ™
on: March 6, 2018, 20:56
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Hi Zumselman, sad to hear about your accident! The Adafruit Motorshield v1 has got two L293DNE motor driver chips, and you can replace them if necessary. It's probably just as cheap to replace the whole shield though!

The motors must be matched to the motorshield. Each driver can supply 600mA continuously, so you should have motors which will draw around the same. If your motor draws more than 600mA (or actually 1.2A at peak) then the L293D chips get overcooked.

Having a power supply that can't supply 2.4A at peak might mean the power supply gets overcooked.

Your new 30A supply should do very nicely!

sn

zumselman
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Posts: 4
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Post Re: I probably killed my first machine ๐Ÿ™
on: March 6, 2018, 22:16
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Hi Sandy and thank you so much for your project and for answering my cry for help. The motors I previously ordered for a different project came with misleading specifications - the title said 0,4A but in the text I now read "rated current / phase 1,7A" which might indicate that the chips will have no chance to survive in this configuration. Even if the supply will last the shield might be the weak part now. I will give it a second try and maybe order two less powerful motors in the near future in case the machine stops again.
Regards
Jรผrgen

sandy
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Posts: 1317
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sandy
Post Re: I probably killed my first machine ๐Ÿ™
on: March 11, 2018, 19:27
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Good luck! It is possible to piggy-back extra L293DNE chips on the adafruit shield to get some extra current out of them (http://blog.tinyenormous.com/2010/06/23/how-to-piggyback-driver-chips-on-ladyadas-arduino-motor-shield/). Also adding heatsinks or a fan will increase the amount of current the board can handle a bit.

zumselman
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Posts: 4
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Post Re: I probably killed my first machine ๐Ÿ™
on: March 14, 2018, 11:12
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Oh, that's an interesting suggestion - thank you very much!

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