New Build Hotend Issues

[RTLdan]

Hi all!
Just got my printer built and I've run into an issue with the Hotend not heating up.
I did a search and found this post: http://forum.seemecnc.com/viewtopic.php?f=54&t=2271
Which is almost exactly like what happened to me. Only problem is, his solution doesn't seem to be mine.

My hotend worked last night. While I tried to tune it, it timed out, so I left off there for the night.
This morning I made only two changes - reflashing with Arduino to reverse my XYZ travel direction, and plugging my endstop connectors into the MAX ports instead of the MIN ports they had been mistakenly put in. Hotend doesn't heat up now. Hmm.

The hotend thermistor appears to be working fine. It agrees with the heated bed about ambient temperature.

The bed heats just fine. I've tried testing both the nano fuses (which appear good) and even swapping them since the bed works.

I've also tried flashing firmware again (with the firmware that has my travel reverse values).
No such luck.

I've also tried turning on the hotend and then messing with my wiring to see if there is a bad connection somewhere in there. Can't find a bad point in the wires via that method.

Throughout the entire build I have been very careful about static, so I can't think of a possibility during the build that would have caused the board to short (plus, as mentioned, the bed heats, extruder motor and XYZ travel just fine, etc...)

Where would it be recommended that I start my investigation to figure out what's going wrong?
Any ideas?

All help is much appreciated.
Thanks in advance!
-Daniel
Portland, Oregon

[Eaglezsoar]

If you have an LCD check the various modes to be sure nothing is set that would effect the hot-end turning on.
Using a multimeter set to measure voltage DC, measure the hot-end output of the Rambo to see if 12 volts is present when the hot-end is
supposed to be on.
Be careful with the probes so that nothing gets shorted. If you get 12 volts at the Rambo it would indicate bad wiring from the Rambo to the hot-end.
If you do not get 12 volts on the Rambo hot-end output then I would once again make the changes to reverse the XYZ rotations as you
indicated that was needed and reflash once again using the Arduino. After reflash, turn off the printer then back on and test to see if the
hot-end now turns on.
Please let us know the results of this.

[RTLdan]

Hi Eaglezsoar!
Thanks for your suggestions.
I went back out and checked the LCD...couldn't find anything that should affect the hot end.
I also tried running it with the LCD unplugged, as I had read in some other threads that the LCD was causing some weird issues.
No luck there.

I did one more attempt reflashing with unmodified firmware - completely stock from the SeeMeCNC site. Nothing.

My next job is to check for the 12v as you said. Just to be sure I know what I'm doing, I want to test the Rambo's far left "Hot 0"
negative and positive terminals for 12v dc with the machine powered on? Can I use the screws themselves as test points or do I have to probe the wire to my hotend right above the terminal connector?

Thanks again for your knowledge and help!
-Daniel

[Eaglezsoar]

Hi Eaglezsoar!
Thanks for your suggestions.
I went back out and checked the LCD...couldn't find anything that should affect the hot end.
I also tried running it with the LCD unplugged, as I had read in some other threads that the LCD was causing some weird issues.
No luck there.

I did one more attempt reflashing with unmodified firmware - completely stock from the SeeMeCNC site. Nothing.

My next job is to check for the 12v as you said. Just to be sure I know what I'm doing, I want to test the Rambo's far left "Hot 0"
negative and positive terminals for 12v dc with the machine powered on? Can I use the screws themselves as test points or do I have to probe the wire to my hotend right above the terminal connector?

Thanks again for your knowledge and help!
-Daniel

Use the screws themselves, and take note of any lit LEDs that you see close to HOT 0 is it on or off?

[RTLdan]

Ok, I'll use the screws themselves. I won't be able to take a measurement for a couple of days as I am leaving on a work trip in a couple hours.
But as far as the LED's... yes, I saw that when I turned on the hotend in Repetier, two LED's were glowing red on the left side of the RAMBo board near the HOT 0 area. Is that significant?
Thanks!
-Daniel

[Eaglezsoar]

Ok, I'll use the screws themselves. I won't be able to take a measurement for a couple of days as I am leaving on a work trip in a couple hours.
But as far as the LED's... yes, I saw that when I turned on the hotend in Repetier, two LED's were glowing red on the left side of the RAMBo board near the HOT 0 area. Is that significant?
Thanks!
-Daniel

If the LED for HEAT 0 is lit that means that everything on the Rambo should be working. The LED for Heat 0 turns on when Heat 0 is active, at that point a Mosfet chip turns on and
allows the voltage to Heat 0. Unless you have a bad Mosfet, which is unlikely because a fuse should have blown first, the Rambo should be good. It's a shame you can't measure the
voltage but we both can wait. Send me a PM if you wish when you get back and measure the voltage. I may lose track of this thread by then and not see your reply. You can send a pm
by clicking on my name and seeing the options. Have a safe trip!

[RTLdan]

Hi again Eaglezsoar!
I got off my lazy butt and took the measurement really quickly...the good news for me is that I am indeed getting 12v at the HOT 0 location - which is also the bad news for me I suppose...time to hunt down my bad wiring! I installed a heater cartridge instead of the two resistors, so I'm a little suspicious that maybe that's giving me trouble. I guess we will see when I get back!

Thanks again!
-Daniel

[Eaglezsoar]

Hi again Eaglezsoar!
I got off my lazy butt and took the measurement really quickly...the good news for me is that I am indeed getting 12v at the HOT 0 location - which is also the bad news for me I suppose...time to hunt down my bad wiring! I installed a heater cartridge instead of the two resistors, so I'm a little suspicious that maybe that's giving me trouble. I guess we will see when I get back!

Thanks again!
-Daniel

That's great news! You won't have to buy a new Rambo. I would suspect the heater cartridge probably opened. They released a bunch of junk ones not to long ago.
It's been my pleasure to help you troubleshoot your problem. We are on this Forum to help others and to learn from others.

[RTLdan]

Hi once again!
Thought I'd give a follow up post.
Back from my trip and got a chance to test my wiring...12vdc all the way up to the cartridge. I just removed the cartridge and it looks kind of "burnt out" so to speak. I've ordered a new cartridge so I'll pop that in when it comes. I might actually order a few more to have on hand for times like this!
Now I'm just happy that I followed Geneb's advice and used quick connectors!

Thanks once again for all your troubleshooting help Eaglezsoar! You are the best!
-Daniel

[Eaglezsoar]

You're welcome. I'm glad you found the problem. Happy printing!