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Is it safe to leave Ultimaker2 DC switch always ON and use AC switch instead?

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Posted (edited) · Is it safe to leave Ultimaker2 DC switch always ON and use AC switch instead?


I don't know if this may be a problem or not, but I use an external SPST (single pole, single throw) switch at the AC side and I leave the switch on the PCB (i.e. DC side) always ON (I did this due to mounting and accessiblity problems in my build). The AC switch turns the Switched power supply on and off, of course.

I am really at the end of my wits here, trying to figure out why my Ulticontroller keeps blowing up (chip U3).

If the above is not a problem, may my problems be due to bad power supplies? If so, how can I check that?

Any help is welcome as these problems are getting very frustrating...


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    Posted · Is it safe to leave Ultimaker2 DC switch always ON and use AC switch instead?

    Hi Umagi,

    First to your procedure powering up the Ultimaker, -you did not state the model you have but I'll assume UM2 here.

    As there is a DC power switch, this one should be switched on last and off first! First AC then the DC! The reason for this might be a slow rising voltage from the DC power supply delivering power to a "computer". As such slow ricing voltage may prevent a proper start reset; this might be the reason for the DC switch... But this answer should normally come from the producer.

    You also said that the U3 IC has been blowing up, -how many times?

    As there are two more OP amps as U3, with supply voltages paralleled, I doubt this problem is caused by the power supply. This U3 OP amp is used for amplify the signal from the (platinum) PT100 temperature probe no1.

    Here I would check the wiring from the extruder and to the control board. The fact is that the heater (containing one wire with 24 VDC and another coming from the PWM controlled ground reference). If the 24VDC line is intermittently come in contact with one of the (two) wires from the PT100 temp sensor, your U3 OP amplifier will be history.

    Please check those wires carefully, the part to mostly pay attention to is; the wiring part from the extruder –to the feeder –also through the hole close to the feeder motor.

    Those wiring thats allways move.

    One last question, does this occur during printing (loosing temp and stop)? Or?

    Good Luck.


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    Posted · Is it safe to leave Ultimaker2 DC switch always ON and use AC switch instead?

    I do not agree with Torgeir.

    There is no "slow voltage rising" on the DC-side of the switchmode power supply that will harm your Ultimaker. If that was the case, thousands of appliances, laptops etc. would blow up daily.

    You can safely leave the DC-switch in the on-position.

    // Per.

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    Posted · Is it safe to leave Ultimaker2 DC switch always ON and use AC switch instead?

    Ok. Have no problem with that, however I'll never said it will blow up, it's is all about a safe reset sequence. Also, -there is a power switch on a PC.

    Not to start a big argument of this, but I'll been working for a very long time with electronics -and just offered my opinion/experience here.



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