Something bad happens when I use the duet _Expansion board

I only use duet and duet_EX,not the shield 0.4.I have already know the noise issue and put some extra CAPs on my board.(I am now trying to put VSSA into my duet_EX).
The phenonmenon is here:
I try to control my E1 extruder and it moves as the order.Then I rise the temperature(LED of heater besides the IPD036 on) and it gets to 185C,the E1 extruder begins to shake silghtly and out of control(A problem of noise?).I find the LED besides the IPD036 shakes(on and off,not quickly) the same as E1(amazing synchronous) after lots of times I try.the E1 goes well sometimes if I set the temperature down(LED is off).
I am sorry for my poor English that I can not describe the phenonmenon accurately.Call me if you have any doubts.
Is this a problem of noise or VSSA issue?How to solve this strange problem?

I suspect that one of the +12V or ground power in connections to the Duet or DueX4 is not making good contact. Power down your machine immediately, and check that the terminal block screws are all tight.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

But I can rise the temperature stably.It goes bad only when the temperature get reached.
I will still try your advice.thank you.
Maybe you can give me other reasons or advices?

Quote
sevenljy
But I can rise the temperature stably.It goes bad only when the temperature get reached.
I will still try your advice.thank you.
Maybe you can give me other reasons or advices?

A poor 12V connection will cause a voltage drop when high current is drawn (e.g. by the heater). While on continuously, the voltage drop will be constant and so the board will be operating on a lower voltage, which will probably work OK. When the temperature is close to the set point however, the heater will be switched on and off rapidly by the PWM control, which will cause an oscillating voltage to the rest of the electronics. While the rest of the electronics may well tolerate a constant under-voltage, a voltage that is changing up & down very rapidly can result in all sorts of misbehaviour.

Dave

Is the first extruder heater also hot when this happens, or have you left it turned off?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I left it turned off and only control the E1 extruder.Is this a problem?the E0 works well.

Quote
sevenljy
I left it turned off and only control the E1 extruder.Is this a problem?the E0 works well.

That's fine, I just wondered whether the power supply might be struggling running 2 hot ends.

Did you check the screw terminals, in particular the ground connections?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I do some experiments today and I am sure that the screw terminals.are tight enough,the voltage is +12V through all the experiments! Maybe it is the noise issue?
The LED of E1 shakes the same way.But when I check the LED of E0,which never shakes(never off through human eyes) as the LED of E1.The PWM control of E1 just works the same way as E0?
I am so confused and I will try more times.
Please give me more prefessional advices.My behaviour is very careful when I do with the electron!

How have you connected ground power to the Duet and DueX4? The ground wiring between the Duet and DueX4 terminal blocks must be short (I suggest 50mm or less), thick, and secure. Don't run separate ground wires from the PSU to the Duet and the X4. Instead, use a 2-way 15A or 30A terminal block close to the Duet and X4 to receive the incoming power from the PSU, then have short wires from that terminal block to the Duet and the DueX4.

If you do this, then the noise issue will only affect the temperature readings. If the ground wire between the two is too long, then there will be more noise, perhaps enough to affect the signal integrity and give rise to the symptoms you describe.

Here is how mine looks.



Edited 1 time(s). Last edit at 04/21/2015 10:52AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

HI.DC42.
YES,my ground power wires are very long between two board.I have no idea that this may be a big problem.I will try.Thank you so much!

I just find out it is not working after I cut off my power and ground wires.Still the same situation as before.
Maybe I should change into shield?

Can you post a photo of how you have the power and (more importantly) the ground connected to the 2 boards?

The shield is easier to use, but a number of us have the DueX4 working well.

Edited 1 time(s). Last edit at 04/22/2015 04:14AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].