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Wiring Harnesses

Posted by Roberts_Clif 
Wiring Harnesses
June 03, 2017 07:52AM
Have been using my 1st 3D printer now for 8 months, the last time I upgraded the software was months ago. Just purchase a 2nd Hictop Aluminum 270X220X190 build area.
I started getting erratic printing, on my Brand New 24V Hictop from day one, after some time and dozens on bad prints, starting diagnosing the errors that were happening .

The errors were many and happened on an unscheduled basis, that is all but one. This error happen from the first time I installed the Marlin Software.
The main problem that was not getting the filament run-out sensor to work correctly, this would appear to function correctly but would always fail with a filament out error.
I have this working on the 1st 3d Printer and it was working correctly until. I had Printed a cover for the Controller board forcing me to re-bundle the wires runs around the 1st Printers controller card.
Then it too had Problems with the filament run-out sensor. This is when I discovered it was not a programming or controller card error.
This is a familiar RepRap 1.3/1.4 style controller from Hictop. for which I have modified with a single heat-sink and cooling fan.
Have also attached heat shields onto the Stepper driver chips not in photo

Started troubleshooting this, started with the SD card diagnostics and found it was in working condition. Replacing the LCD Cables the problem still existed.

What was discovered was that using the Spiral wrap tube and tie wraps to bundle all cables closely together, is really not a good Ideal.

What was happening is the Stepper motor cables were injecting their signals to the other cables making for a very erratic behavior.
As you can see all my cables are running down the side with the stepper motor connectors, the signals being combined at this point causes the crossover.

1. Using a modified endstop board with led as my filament run-out sensor, the signals cross feed into the circuit via the cabling, and was inadvertently thinking filament was out.
2. Signals were cross feeding into the SD card cable and making erratic print moves. Including crashes into the Hotbed and other X and Y axis erratic moves.
3. Most likely there were instances the signals bleeding into the Thermal Sensor as I was getting Thermal shutdown readings, when temperatures were stable.

Re-Ran all cables loosely giving appropriate space from the stepper cabling to avoid signals being inject into the adjacent cable.
Specifically the Wires around the Controller were separated according to type Stepper / heaters or sensors / end-stops.

Separating the stepper signal cabling giving adequate space between control cables, has solved all my issues.
Re: Wiring Harnesses
June 03, 2017 08:09AM
All cables carrying small signals (thermistor leads) or high intermittent currents (motor, heater etc.) should be twisted pairs. Twisting reduces the chances of the cable inducing or having signals from nearby wires induced in them via magnetic coupling. Motors typically have two coils and four wires, The wire pairs for each coil should be twisted, and the two pairs of twisted wires kept close to each other. Shielding cables reduces the chance of capacitive coupling (if the shield is properly grounded at one end). Never share a ground wire between a high current load and a small signal pair.

I make a lot of the cables in my printer by twisting wires for them. I designed and printed a tool for the purpose.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Wiring Harnesses
June 04, 2017 09:40PM
Well I was mistaken. Still have problems with the SD card Reader on the Hictop 3DP12.

It is really strange. Can take the 3 Controllers and the 3 LCD2004 displays and get them all to work correctly on my Hictop 3DP11 that has a 12v at 20 amp supply.

Now here is my dilemma if I take any of the cards connect it too my 3DP12 which has a (1) 24v 15 amp power supply it errors only when the LCD is attached to the Top Frame.
If I uninstall the MLCD2004 and set it in front of the printer it works perfectly shown in the Photo below.

I will try most anything to try to fix this problem, as I really do not want to have the Display forever in front of the 3D Printer.

Looking for a solution.

1. I have purchased a replacement 24Volt 20amp Supply has the exact same problem.

Edited 9 time(s). Last edit at 06/05/2017 07:13AM by Roberts_Clif.
Re: Wiring Harnesses
June 05, 2017 07:20AM
Have just measured a voltage difference of 599mv from ground to the Extruder stepper motor case will try grounding and return the MLCD2005 Display back on top.
The voltage is originating from the nozzle heater as there is a voltage difference of 6mv from the nozzle to the stepper motor case.

Being is such close proximity to the MLCD2004 this indeed may lead to a solution. The X-Axis stepper does not have a residual voltage but it too will be grounded.

After further inspection it was originating from a shorted temperature sensor the voltage was 4.6v in the idle position and dropped to 599mv while running.

I wrapped the washer holding the sensor in with high temperature tape isolating it from shorting.

The MLCD2004 display mounted back on top, stopped working again will remove and place in front of the 3D Printer and continue testing for a solution.

Attached display to front just out of the hotplate zone no errors.

Actually this is becoming too much of a chore I will simply use one of my spare MLCD2004 displays and continue testing for a solution.

It appears the location (1) is part of the problem. most likely there is too much interference at the location will try some shielding.

1. By location I mean that the cabling has to be routed a certain way to reach the MLCD2004.

Edited 11 time(s). Last edit at 06/05/2017 10:47AM by Roberts_Clif.
Re: Wiring Harnesses
June 06, 2017 07:48PM
I have made a EFI Shield for Hictop Aluminum Printers download from Tinker-cad below
Hictop Controller Cover

Make a trip to your local hardware store and purchase a roll of Aluminum Duct Tape about $4.00.

1. What is required is to print the Above case or one of your own design.
2. Cover all areas inside the Printed case Include a least one screw for GND. Making sure you cut out all the holes. Added A fan for cooling purposes.
3. Attach the Cover to your Controller Card and You are Done.

4. For added protection covered the MLCD2004 cover also (THIS IS NOT MY DESIGN) It can be downloaded from tinkercad.

If you use anything here please state where you found it.

Edited 3 time(s). Last edit at 06/07/2017 03:19PM by Roberts_Clif.
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