Possible Short in the Power to the Heated Bed

You hae pictures?

 

Just to update. Had recieved a message via the Facebook team saying to send the bed back to Jerry in USA for repairs (because the plug was fused together so a replacement wire wouldn't suffice). I sent it off the next day.

The following day I get an email from Braydon and Jerry saying they are sending me replacement wires. I think they are all getting confused with the multiple different people trying to help me with this issue...and so am I lol.

Anyway, bed is somewhere on the way to USA.. hopefully it comes back repaired and I get my shipping cost reimbursed as promised via Facebook.

 

According to tracking my bed has been delivered to the team. Now we wait!!! I still have not been reimbursed for the shipping cost or had any replies after posting the bed off.

Looking at other peoples pictures, I'm not all that convinced that the wire being too tight (as mentioned in the information email) was the reason for all these melted plugs and wires. It seems to start only on the negative terminal of the plug.

Has the kaptone heater been changed from previous iterations of the printer? It's almost like the current draw from the heater was too much for the wires/plug to handle. Maybe a fuse should be included in line? Thougths?

 

Wow I'm having burnt wire problems too and sent 3 emails . Not a single reply . Seems They pick and choose who they wanna help out . Thanks.

 

Thank god I had my printer on a titled table and nothing flammable ..

 

Similar problem on earlier heat bed where it goes straight to the board without the connector this week. I have a picture of my bed connectors to show the difference. My problem was at the 11A power connector where the + line was scorched. I have two pics of the connector (MSTBA4 on schematic) which shows bubbling on the side and a scorched wire. I could not get continuity between the terminal and the pin on the bottom of the board so I believe this has shorted out inside the connector and I must replace it.

***Oddly, when I tested the voltage at the terminal for the heater, I did get 12V but the led never lit when the bed was being commanded to heat. I tested this by placing the positive multimeter lead on the heater terminal + and the ground lead to the gnd on the 11A power terminal... but when I tested gnd on the heater terminal I did get 0V. I am no electrical engineer so I am accepting there was not 12V on the heater terminal at least with sufficient amperage to heat anything.

I could place my hand on top of the board and see the temp respond in Repetier so I knew it wasn't the thermister. When I turned on the heater manually in Repetier I would get 5V to the gate pin of the mosfet so I knew D8 was driving it high (and the green graph on Repetier showed power on). 0v when off. I saw some discussions in the forums around the drive voltage not fully opening the MOSFET creating heat, but mine did show 5.0v, not less. So for now I won't dig into other MOSFETs. Those discussions seemed to be for temporary fuse related cutouts.

I could see 1 ohm on the heater element when testing ohms at the power terminal to the heater (not sure this is a valid check since I didn't disconnect the power lines, but I think it is). I had continuity between the polyfuse terminals so I think it is good.

I was about to desolder the MOSFET and test it (since I got 12V on the power line on the check above) when I came across this thread. Feeling stupid since this seems the most obvious place to start troubleshooting now. The connector scorching and disfigurement led me to check the terminal and with no continuity from the screw terminal to the corresponding pin under the ramps board it makes me think this is the culprit. That and the fact the LED is not lighting makes me pretty sure this will do it once fixed.

I smelled some electrical burning for last 2 prints... never a good sign but I couldn't identify its source on visual inspection and I was hoping it was filament or kapton on the hot end... I guess now I know...

I had added a fan and tapped power from this terminal so perhaps the connection I put in place wasn't good enough creating resistance (and resultant heat) but I think I may be just fixing a symptom to the documented design weakness... we'll see once I replace it.

Connected a schematic showing the troubleshooting in case anyone is interested.

 

With my above resistance measured at 1.0 ohm for the heatbed... perhaps this is my problem. I think that solving for I above I get 12A which would exceed the 11A power supply and the polyfuse. I'll think on this. Any way to increase the ohms on the heater (the thread I quoted from uses the word calibration) or is that just what it is? I may try to get a current reading once I get the connector, but not sure my multimeter can hack that and not confident in my inductance related DC meter.

I have ordered the RHEF1500CT-ND Fuse and IRLB3036 MOSFET as well. Sort of feels right to change those out if I am under the hood with a soldering iron.

 

Anyone get the replacement wiring yet?

 

I was one nail close to not using their wiring when I got my Y-Axis kit. After getting the email about the shorting wires, that sealed the coffin and I went and assembled my own harness using locking Molex's. I feel 100% safer knowing I have a properly built harness under there.

 

The new connector is rated for higher amps. It will resolve any and all issue. The picture with the end stop on fire is very confusing and wouldn't relate at all to this issueissue

 

So the recent information email talks about everyone receiving a return labelled box for the entire bed to be sent back.. thats great to hear that the team is going to that length to make sure the fix is in place for everyone.

I just hope I hear some news soon about my bed being returned fixed and/or reimbursment for the shipping cost. Its been a week since it was delivered to them... and I've been about 2 weeks without any printing action!

 

I know they have plans to take good care of you, but I'll press them to get yours out ASAP

 

I bought the new R1 (for replacing the previous R1), and I wanted to know if I using a MOLEX connector (like used for EIDE HDD of PCs) could solve the problem ?

 

I don't think those are rated to 9-10A nor should you use something with no locking latch.