Electrical wires melting

Tarantula hardware issues, upgrades and configurations
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Zebriah
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Joined: Sat Jun 23, 2018 3:18 am

Electrical wires melting

Post by Zebriah » Sat Jun 23, 2018 2:59 pm

Greetings, I have 2 Tevo Tarantula's and my second has only been plagued with small issues since I got it. So to go over it's current issue I'll explain. When I first got the printer I also got a mosfet for the heated bed and a modular PC PSU with connectors to wire up to the tevo. Out of the box everything worked but I was constantly getting heat creep and it would jam. After finally just replacing hot end with e3d one it was working. But not for long. My mosfet started getting so hot it melted. I removed it and connected bed through the board and tried this. It worked wonderfully for a few weeks. Until I broke the acrylic y. So, I got the aluminum Y from frankhauser and now when I connected it all again the wires to the PSU melted on heat up. I switched wires and tested just heating the nozzle. No issue. Heat the bed and it starts melting. I tested resistance of bed and I'm getting ~1.4 ohms. I believe there is a short but how do I find it and fix it?

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royg
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Re: Electrical wires melting

Post by royg » Sun Jun 24, 2018 12:47 am

When you test the heated bed and get hot wiring, is the heated bed also heating up? As for the heated bed resistance that you measured, most low cost multimeters are fairly inaccurate when measuring resistances under ~5 ohms, so the ~1.4 ohms that you measured may or may not be right. As you are lucky enough to have two Tarantulas, I would recommend that you measure the heated bed resistance of both heated beds using the same multimeter for both readings, and compare readings. That may give you an indication of whether the questionable heated bed has a low resistance heater element. (That's assuming that your two Tarantulas both have the same physical size (i.e. 200 x 200, or 200 x 260mm) heated bed.)

As for the wires melting, definitely indicates excess current, assuming the replacement wires that you've used are rated for the current. I wonder if your MosFET has died causing the excess current flow. The MosFET that I've been using for a long time now came from Tevo, and works great - never any sign of overheating or failure of the Tevo MosFET. I think this Tevo MosFET was originally intended for the Tevo Black Widow, but it works well on either 12 volt or 24 volt printers.

Link to Tevo MosFET at Aliexpress Tevo Store

Not very conclusive advice I know, but I hope that has at least helped to some extent.

Regards,

RoyG
Tevo Tornado (MKS Gen L version) - Genuine E3dV6 - BLTouch
Tevo Tarantula with a Laser Cutter/Engraver Add-on.
OctoPi (on an Odroid XU4)
Fusion 360, Cura, Slic3r, Ideamaker

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