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Re: Taz 5 Temperature Drops

Posted: Mon Feb 05, 2018 2:41 pm
by ScottW
otakuex wrote:
Mon Feb 05, 2018 2:05 pm
Thanks ScottW.
Just to make sure I didn't make a mistake, I recently replaced the thermistor and heater cartridge with the following parts. ... thermistor ... %2F+19+ohm
- 24v/19ohms option
You could double-check with Lulzbot tech support, but those certainly look like the correct parts to me.
otakuex wrote:
Mon Feb 05, 2018 2:05 pm lost me on 2). Are you talking about writing a custom gcode file? Can you give me a little more instruction or example on that? I haven't done that before.
There are PID controller values the firmware uses to help stabilize and prevent overshoot/undershoot of target temperature. There are defaults in the firmware which are usually fine, but you can also set your own values. The firmware also includes a testing routine, called "PID Autotune", which will test different power levels while watching temperature behavior and then spit out recommended PID settings based on those tests.

Beware that other problems (like bad connections, insufficient power, bad thermistor, etc) can cause Autotune to return bad numbers. So those things need to be ruled out first. I really don't think PID values are your problem -- because it is so intermittent.

But to check and set PID values for the hotend:
  • If you go to console and enter a "M503" command, the firmware will respond with current settings. Look for a line that starts with "M301" and jot down the numbers for P, I, and D values shown on that line. I think the firmware defaults for the standard Hexagon are P28.79, I4.83, and D108.51, so that's probably what you'll see.
  • Then with the hotend at room temp, send the command "M303 S210". The hotend will heat up, then hold around 210 for a while, and issue several messages over a period of a few minutes with P, I, and D values. When the command completes, look for the last set of those numbers and jot them down.
  • If the values from autotune are far different than firmware defaults (particularly if there is a really big P number) with a standard Hexagon, I would again suspect some other problem -- like power or wiring (or thermistor/heater, but you've replaced those). Otherwise, you can enter the new values by going to the console and sending "M301 Pxx.xx Ixx.xx Dxx.xx" command (where you replace the "xx.xx" values with those suggested by Autotune).
  • After setting the new values with M301, send an M500 command to store the values to memory -- otherwise they will be lost at next power cycle or connection. Finally, run the M503 again and verify that the values you entered are now shown.

Re: Taz 5 Temperature Drops

Posted: Thu Feb 15, 2018 7:28 pm
by mbur371189
I run my taz 5 with octoprint also. I had temp issues also. Mine had to do with the thermistor. I was able to fix the one I had. It was a bad soldier joint. It read fine with the dvm but during certain movements it showed itself. You mentioned that it's a very long print does it show up at the same time every time? I'd check that whole wiring run if possible. Good luck

Re: Taz 5 Temperature Drops

Posted: Wed Jan 09, 2019 11:35 pm
by otakuex
Thanks so much for your replies. After a YEAR (I moved and had to put this on hold for some months), I finally found the issue. I added a 2nd fan for the hotend heatsync in parallel with the mini blower. It was causing too much draw it seems and it was pulling power away from the thermistor somehow? As soon as I disconnected it, the temp shot up to what it should be in seconds. I figured it out by running a print and disconnecting one component at a time and monitoring the temp. Took a quite a while.

A little explanation so you don't think I'm dumb... I was getting constant filament jams and assumed it was heat creep, so I printed a duct ( ) and got this 40mm 5v 0.19a fan from ebay ( ... %2FA%3D%3D ). I connected it in parallel to the mini blower (also 5v) and everything seemed to work. I still got the filament jams and eventually noticed the temp drops, and I assumed they were always the problem and I just hadn't noticed before adding the fan, but now I guess some other factor was causing jams before adding this fan.

Now I found that my mini blower is dead - I cut the lines and confirmed it's still getting 5v. But even with just the 40mm fan connected, there's still drops. So I need to power it another way. Is there anywhere on the control board where I can get constant 5v, or somehow in conjunction with the thermistor being activated? I'd prefer not to down grade back to the less effective mini blower at a crazy cost of $18+shipping.

Re: Taz 5 Temperature Drops

Posted: Thu Jan 10, 2019 3:14 pm
by zachah
If you have access to a digital multimeter you may want to test the voltage of the PSU.

Plug the PSU (power supply unit) into a worked outlet, and then measure the DC output of the 4 pins on the output of the PSU.

Pins 1 and 2 will be live, while pins 3 and 4 will be ground. You should get 24V DC output when testing a live and ground pin.

Re: Taz 5 Temperature Drops

Posted: Fri Jan 11, 2019 2:52 pm
by otakuex
PSU pins 1+3 and 2+4 are 24.16VDC on each. I connected the new hotend heatsync fan to a dedicated 5V power supply. Would be nice to connect to the control board. Please let me know if anyone knows how I might do this other than the pins for the mini blower. I still have to clear the last filament jam. Will update after that.