Powering the BL touch directly from the power supply.

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Powering the BL touch directly from the power supply.

Postby gCreate_Kyle » Wed Jul 13, 2016 1:41 am

There has been reoccurring problem with the BL touch auto bed leveling sensors. In some cases, they are not receiving enough power. This causes the BL touch to fail the self-test, blink its red LED and refuse to work. Other symptoms are inconsistent measurements, early triggering, or the Z-axis climbs during the bed probing routine.

Fortunately, the fix is simple and easy to do. You need to run a 5V wire from the power supply directly to the BL touch. Since we are running more connections to the power supply, we might as well run a 12V wire to fix the flickering LED light too.

To access the extra plugs of the power supply you need to remove the back of the LCD screen bracket.
RearLCDscreenScrews.PNG

SideLCDscreenScrews.PNG


There will be a bunch of unused plugs from the power supply inside. 3.3V(orange), 5V(red), 12V(yellow), ground(black) circuits are available.

DSC_0031.JPG


Find a 4 pin connector with one set of wires running into it. Plug the white end of the cable into the 4 pin connector.

extra_bltouch_wire(3).jpg


DO NOT USE A 4 pin connector with 2 sets of wires running into it. It may not be powered.

DSC_0022.JPG


Run the cables into the electronics box.

DSC_0023.JPG


The red wire provides 5V for the BL touch. Plug it into the pins shown in the picture. If you had a jumper in these pins, you can remove it.

extra_bltouch_wire(1).jpg


Before plugging in the yellow and black wires, unplug the green wires from the 12AUX pins. You can remove the green wires from the electronics box.

12vAuxPinsRamps.png


Plug the yellow and black cables into the RJ-45 connector as shown in the picture.

extra_bltouch_wire(2).jpg


Tidy up the wires and reattach the back of the LCD screen cover and you will be ready to print.

If you need the wiring harness contact us at support@gcreate.com or submit a support ticket on the website.
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Re: Powering the BL touch directly from the power supply

Postby neobobkrause » Sat Jul 30, 2016 11:47 am

I just installed the wire harness for Powering the BL touch directly from the power supply that arrived yesterday.

But the bl touch probe still fails when the unit is first powered up after a long period of bring powered off. I imagine this is because some capacitor somewhere isn't fully charged before the probe's self-test begins. Is there a way to introduce an additional one to two second delay in the firmware boot sequence before that self-test begins? Otherwise I'm destined to always double boot every morning.

Another issue that came up after installing the harness as described in Kyle's post is that the LED lights no longer lit up. There's 12.05v coming across the black and yellow wires of the new harness, and I'm plugging it into the correct pins as shown in the photos. I put a voltage meter on the same headers on the gantry end of the RJ45 and found the same voltage. Stumped with nothing else to chase down, I tried reversing the connector of the new harness in the electronics box -- and the lights lit up.

With an eye toward keeping that wiring to spec, should I keep the connector reversed, or should I reverse the LED leads coming off the headers in the gantry?

Thanks,

- Bob
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Re: Powering the BL touch directly from the power supply.

Postby gCreate_Kyle » Mon Aug 01, 2016 11:52 am

With an eye toward keeping that wiring to spec, should I keep the connector reversed, or should I reverse the LED leads coming off the headers in the gantry?


Reverse the LED leads coming off the screw terminals in the extruder.

Is there a way to introduce an additional one to two second delay in the firmware boot sequence before that self-test begins?


There is no way to do this. The BL touch automatically does the self test when it is powered. You can try adjusting the position of the set screw found on the top of the BL touch. This will not effect the offset of the probe. This set screw sets the "up" position of the probe.
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