Temperature Drops after Print Starts

Hey Guys,
So I had to put in new thermistor recently, did some other structural changes (60mm height increase) and wired in a fan which isn’t currently connected. Yet now I am getting this issue with my hotend where once the print start the temperature drops even though it looks like the extruder is still rocking it.

I ran PID autotune, stored the values, brought the bed and then the hotend up too 230C using Repetier. Then I dropped in the GCODE. You can see down below the temperature curve. The temperature is fine and steady, jumps up the last five degrees needed (235C) and then the temp proceeds to drop while it appears as if current is still being put thru the heater. I canceled the print shortly there after as the extruder was starting to jam as it could no longer melt the plastic.

I am not sure if this is a software, hardware or gcode problem.

First part of code. Full package attached.

; generated by Slic3r 1.0.0RC2 on 2014-11-22 at 13:28:42

; layer_height = 0.25
; perimeters = 4
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = .35
; perimeter_speed = 60
; infill_speed = 90
; travel_speed = 130
; nozzle_diameter = 0.35
; filament_diameter = 2.8
; extrusion_multiplier = 1
; perimeters extrusion width = 0.35mm
; infill extrusion width = 0.39mm
; solid infill extrusion width = 0.39mm
; top infill extrusion width = 0.39mm
; support material extrusion width = 0.35mm
; first layer extrusion width = 0.38mm

G21 ; set units to millimeters
M190 S115 ; wait for bed temperature to be reached
M104 S235 ; set temperature
G28 ; home all axes
M109 S235 ; wait for temperature to be reached
G90 ; use absolute coordinates
G92 E0
M82 ; use absolute distances for extrusion
G1 F1500.000 E-1.10000
G92 E0
G1 Z0.250 F7800.000
G1 X72.354 Y77.224 F7800.000
G1 E1.10000 F1500.000
G1 X73.434 Y76.344 E1.12091 F1800.000
G1 X74.664 Y75.684 E1.14186
G1 X75.994 Y75.284 E1.16270
G1 X77.384 Y75.144 E1.18366
G1 X112.604 Y75.144 E1.71223
G1 X113.994 Y75.284 E1.73319
G1 X115.324 Y75.684 E1.75404
G1 X116.554 Y76.344 E1.77499
G1 X117.634 Y77.224 E1.79589
G1 X117.764 Y77.354 E1.79865
G1 X118.644 Y78.434 E1.81956
G1 X119.304 Y79.664 E1.84051
G1 X119.704 Y80.994 E1.86135
G1 X119.844 Y82.384 E1.88232
G1 X119.844 Y108.914 E2.28046
G1 X119.704 Y110.304 E2.30143
G1 X119.304 Y111.634 E2.32227
G1 X118.644 Y112.864 E2.34322
G1 X117.764 Y113.944 E2.36413
G1 X108.944 Y122.764 E2.55132
G1 X107.864 Y123.644 E2.57223
G1 X106.634 Y124.304 E2.59318
G1 X105.304 Y124.704 E2.61402
G1 X103.914 Y124.844 E2.63499
G1 X77.384 Y124.844 E3.03314
G1 X75.994 Y124.704 E3.05410
G1 X74.664 Y124.304 E3.07494
G1 X73.434 Y123.644 E3.09589
G1 X72.354 Y122.764 E3.11680
G1 X72.224 Y122.634 E3.11956
G1 X71.344 Y121.554 E3.14047
G1 X70.684 Y120.324 E3.16142
G1 X70.284 Y118.994 E3.18226
G1 X70.144 Y117.604 E3.20322
G1 X70.144 Y82.384 E3.73179
G1 X70.284 Y80.994 E3.75275
G1 X70.684 Y79.664 E3.77360
G1 X71.344 Y78.434 E3.79455
G1 X72.315 Y77.263 E3.81737
G1 X72.614 Y77.484 F7800.000
G1 X73.644 Y76.654 E3.83722 F1800.000
G1 X74.804 Y76.024 E3.85703
G1 X76.074 Y75.644 E3.87693
G1 X77.384 Y75.514 E3.89668
G1 X112.604 Y75.514 E4.42525
G1 X113.914 Y75.644 E4.44500
G1 X115.184 Y76.024 E4.46490
G1 X116.344 Y76.654 E4.48471
G1 X117.374 Y77.484 E4.50456
G1 X117.504 Y77.614 E4.50732
G1 X118.334 Y78.644 E4.52717
G1 X118.964 Y79.804 E4.54698
G1 X119.344 Y81.074 E4.56687
G1 X119.474 Y82.384 E4.58663
G1 X119.474 Y108.914 E4.98478
G1 X119.344 Y110.224 E5.00454
G1 X118.964 Y111.494 E5.02443
G1 X118.334 Y112.654 E5.04424
G1 X117.504 Y113.684 E5.06409
G1 X108.684 Y122.504 E5.25129
G1 X107.654 Y123.334 E5.27114
G1 X106.494 Y123.964 E5.29095
G1 X105.224 Y124.344 E5.31084
G1 X103.914 Y124.474 E5.33060
G1 X77.384 Y124.474 E5.72875
G1 X76.074 Y124.344 E5.74850
G1 X74.804 Y123.964 E5.76840
G1 X73.644 Y123.334 E5.78821
G1 X72.614 Y122.504 E5.80806
G1 X72.484 Y122.374 E5.81082
G1 X71.654 Y121.344 E5.83067
G1 X71.024 Y120.184 E5.85048
G1 X70.644 Y118.914 E5.87037
G1 X70.514 Y117.604 E5.89013
G1 X70.514 Y82.384 E6.41869
G1 X70.644 Y81.074 E6.43845
G1 X71.024 Y79.804 E6.45834
G1 X71.654 Y78.644 E6.47815
G1 X72.484 Y77.614 E6.49801
G1 X72.575 Y77.523 E6.49993
G1 X72.884 Y77.754 F7800.000
G1 X73.844 Y76.954 E6.51869 F1800.000
G1 X74.944 Y76.374 E6.53735
G1 X76.144 Y76.004 E6.55620
G1 X77.384 Y75.884 E6.57489
G1 X112.604 Y75.884 E7.10345
G1 X113.844 Y76.004 E7.12215
G1 X115.044 Y76.374 E7.14100
G1 X116.144 Y76.954 E7.15966
G1 X117.104 Y77.754 E7.17841
G1 X117.234 Y77.884 E7.18117
G1 X118.034 Y78.844 E7.19993
G1 X118.614 Y79.944 E7.21859
G1 X118.984 Y81.144 E7.23743
G1 X119.104 Y82.384 E7.25613
G1 X119.104 Y108.914 E7.65428
G1 X118.984 Y110.154 E7.67297
G1 X118.614 Y111.354 E7.69182
G1 X118.034 Y112.454 E7.71048
G1 X117.234 Y113.414 E7.72924
G1 X108.414 Y122.234 E7.91643
G1 X107.454 Y123.034 E7.93518
G1 X106.354 Y123.614 E7.95385
G1 X105.154 Y123.984 E7.97269
G1 X103.914 Y124.104 E7.99139
G1 X77.384 Y124.104 E8.38953
G1 X76.144 Y123.984 E8.40823
G1 X74.944 Y123.614 E8.42708
G1 X73.844 Y123.034 E8.44574
G1 X72.884 Y122.234 E8.46449
G1 X72.754 Y122.104 E8.46725
G1 X71.954 Y121.144 E8.48601
G1 X71.374 Y120.044 E8.50467
G1 X71.004 Y118.844 E8.52351
G1 X70.884 Y117.604 E8.54221
G1 X70.884 Y82.384 E9.07077
G1 X71.004 Y81.144 E9.08947
G1 X71.374 Y79.944 E9.10831
G1 X71.954 Y78.844 E9.12698
G1 X72.845 Y77.793 E9.14765

83208x4.gcode (1.31 MB)

Try the print again, but with the bed turned off (remove this line of your gcode file:

M190 S115 ; wait for bed temperature to be reached

If the hot end temperature drops again it’s worth noting. If the temperature does not drop, we’ll look in another direction.

No dice…

I am ready for the next suggestion.

If it’s doing that with the bed off then it’s not something power supply related. Lets eliminate software, by using a different print host, like Printrun (Pronterface): https://www.lulzbot.com/support/downloads

Load the same gcode file and give it a run. If it happens again, we can look at the hardware, both the heater resistor resistance, and the RAMBo board (look for discoloration on the hot end connectors/mosfet underneath E0 heater, while powered off of course).

If it’s an AO-100, it might have a RAMPS board. connections are similar, layout is a bit different but you should be able to find a similar diagram easily enough.

Orias & Piercet
Thanks for the help, I got it fixed with some help from a couple guys on the RepRap IRC, (SystemsGuys & phil190). They suggested that I wiggle all the connections while the hot end is heated. Though the temp didn’t drop again, when I wiggled the four pin connector. I think I got a little jolt and it was quite toasty. It appears the standard connector, had partially melted at some point. Not sure what would have cause this but when I bypassed the connector that problem seem to have gone away and I got half decent print. Looks like need to adjust my extrusion settings but very happy to finally have finished print.

Yeah that is not a happy connector all right. Glad you got it figured out though!

I’ve had that same connector on my AO101 melt too.
IMHO those connectors do not have a high enough amperage rating for the job they are being asked to do. I upgraded mine to a higher spec connector. Been fine ever since.

I don’t know enough about connectors to pick a better one but I would like to. I had to hard wire it in to keep going and I want to be able to swap out hotends.

The only time we’ve seen something like that is when the connection between the two connectors was slightly intermittent. Make sure that the pins are fully seated within the connector housing.

What you mean its not completely idiot proof?! lol you are probably right. I can’t speak for others but I may have not had the connector fully seated before I initialized it.

BTW the pins for those things are kinda pricey!?

They can be pricey, but they’re handy to have if you ever need locking connectors.