Temperature Sensor Not Reporting

[mm_build 1]

So the other day I took apart my hot end, and since then the temperature hasn't been reporting properly. I really don't think I "did anything" to the hardware, but I have a hard time thinking it's a coincidence.

Once the hot end was disassembled (top off, bottom off, pcb unscrewed) I was tilting the machine back and forth to make some adjustments to the fan, when I noticed the blue LED flicking on and off. I eventually traced this to a loose connection at the plug to the main PCB. Also during this time the reported temperature in Pronterface changed to 0. I reset the machine and it came back with a temp of about 1 or 2. Anyways, I ignored that until I could glue the wires into the white housing which appears to have fixed all connection problems. The problem is now, whenever I connect to my machine it reports a temperature of about 27.83 degrees, whether I have the thermocouple plugged in or not, (not sure if that's normal). Also, it does not report changes to the temperature any longer. I can heat until the plastic starts smoking but it will still report the same 27-28 degrees.

I tried removing my thermocouple for inspection, but there is a screw in the aluminum block which will not budge. Also the TC is loose within the block, I can move it in and out about 3-4mm. I haven't really played with this part before so I don't know if that is normal.

[joergen 2]

So the other day I took apart my hot end, and since then the temperature hasn't been reporting properly. I really don't think I "did anything" to the hardware, but I have a hard time thinking it's a coincidence.

Once the hot end was disassembled (top off, bottom off, pcb unscrewed) I was tilting the machine back and forth to make some adjustments to the fan, when I noticed the blue LED flicking on and off. I eventually traced this to a loose connection at the plug to the main PCB. Also during this time the reported temperature in Pronterface changed to 0. I reset the machine and it came back with a temp of about 1 or 2. Anyways, I ignored that until I could glue the wires into the white housing which appears to have fixed all connection problems. The problem is now, whenever I connect to my machine it reports a temperature of about 27.83 degrees, whether I have the thermocouple plugged in or not, (not sure if that's normal). Also, it does not report changes to the temperature any longer. I can heat until the plastic starts smoking but it will still report the same 27-28 degrees.

I tried removing my thermocouple for inspection, but there is a screw in the aluminum block which will not budge. Also the TC is loose within the block, I can move it in and out about 3-4mm. I haven't really played with this part before so I don't know if that is normal.

Double and triple check if the TC cables are actually connected to the TC board (and check if the green terminal is connected to the TC board)... Siert emailed me the other day that if the TC cable gets disconnected, the arduino gets into a undefined state and can potentially overheat the head.

[mm_build 1]

Haven't sorted out the problem yet. I don't have a multimeter handy to test it but as far as I can tell everything is connected. It's hard to tell what's going on inside of the clips, but it feels like it's solid and I've unplugged it and plugged it back in so many times now that it should have worked at least once. I even took off my glue and wiggled the wires inside to make sure they made contact. I updated the firmware to try and reset the undefined thing, and it could be nothing but it didn't sound right when I updated. Usually it makes that whirring sound, but it lasted a long time and the sound didn't sound normal. It sounded like someone dropping a bomb from a long ways.

PS, would it burn something out if any of these wires touched? When I tugged on the ends to see which one was loose, the red and black came out together, so I pulled the green one out too. I was touching them to the terminals to see which ones make the light go on, and there is a good chance they made contact with each other and / or the pins on the board, because holding 3 wires into position with two fingers is harder than it seems in theory. :oops:

[joergen 2]

Haven't sorted out the problem yet. I don't have a multimeter handy to test it but as far as I can tell everything is connected. It's hard to tell what's going on inside of the clips, but it feels like it's solid and I've unplugged it and plugged it back in so many times now that it should have worked at least once. I even took off my glue and wiggled the wires inside to make sure they made contact. I updated the firmware to try and reset the undefined thing, and it could be nothing but it didn't sound right when I updated. Usually it makes that whirring sound, but it lasted a long time and the sound didn't sound normal. It sounded like someone dropping a bomb from a long ways.

PS, would it burn something out if any of these wires touched? When I tugged on the ends to see which one was loose, the red and black came out together, so I pulled the green one out too. I was touching them to the terminals to see which ones make the light go on, and there is a good chance they made contact with each other and / or the pins on the board, because holding 3 wires into position with two fingers is harder than it seems in theory. :oops:

It becomes hard to tell without a multimeter and I do assume the 5V comes from the arduino voltage regulator... to check if you killed your arduino, see if it still connects to your computer without powering up the rest of the printer.

if you've got your multimeter, you should see 5V between the black and red (up on the print head on the TC board), and the blue led should light up once it gets power via USB. you should also see about 200-250mV between green and black, since that is the proper output of the TC board.

btw, I wasn't referring to the green/red/black cables when I asked to check the connection, but actually the orange/red cables that come from the actual thermocouple.

[mm_build 1]

I am able to connect to the printer without the power plugged in, just with the USB cable.

I measured the voltage at the PCB from Red to Black it is approximately 4.84V. I measured the voltage from Signal (green) to Black, and it is about 20 mV. Holding the multimeter to the contacts causes the voltage to drop steadily in 0.1mV increments until it was about 10mV. Coming back a few minutes later it was up to 17mV but started dropping again as I probed. At the bottom of the of the TC board where wires to the TC are soldered, I could not get any reading between yellow and red.

[joergen 2]

I measured the voltage at the PCB from Red to Black it is approximately 4.84V. I measured the voltage from Signal (green) to Black, and it is about 20 mV. Holding the multimeter to the contacts causes the voltage to drop steadily in 0.1mV increments until it was about 10mV. Coming back a few minutes later it was up to 17mV but started dropping again as I probed. At the bottom of the of the TC board where wires to the TC are soldered, I could not get any reading between yellow and red.

you might have killed your TC board... (you really did measure only 20mV, not 200mV?)

as I said, the board puts out 10mV/C, so at room temp you should see 200-250mV +-30mV or +-3C error). if you see less, and the temp/voltage doesn't increase when heating (you can just use a hairdryer just to see if the TC reacts... this should increase the output to 500-700mV), it's either dead, or more experienced users need to weigh in on this issue.

[mm_build 1]

you might have killed your TC board... (you really did measure only 20mV, not 200mV?)

Yep, twenty not 200.

I heated up the nozzle in Pronterface (haven't managed to break the heater ..yet), it got nice and hot. The voltage measured ~50mV before heating, and the same after. The situation was the same where the longer I held the multimeter to the contact points, the lower the voltage would drop. It went down to 30mV in a matter of about 20 seconds. *sigh*

[Daid 306]

The TC Board (with the blue led) reports it's own temperature if it doesn't find a thermocouple connected. So a possible cause could be a broken wire in the thermocouple or a broken thermocouple.

[joergen 2]

you might have killed your TC board... (you really did measure only 20mV, not 200mV?)

Yep, twenty not 200.

I heated up the nozzle in Pronterface (haven't managed to break the heater ..yet), it got nice and hot. The voltage measured ~50mV before heating, and the same after. The situation was the same where the longer I held the multimeter to the contact points, the lower the voltage would drop. It went down to 30mV in a matter of about 20 seconds. *sigh*

If you disconnect the red/orange TC wires from the TC board, and measure the voltage between the 2 wires, you should see about 0.7mV at room temp, and if you heat the TC up a bit (hairdryer) to 60-70C, you should see about 2-3mV... this requires a good multimeter... if your multimeter has a temp function and you have a TC that came with it, you can 1st hook up this TC, and see what temp and voltage it is giving you. then hook up the orange/red wires of the UM TC to your multimeter, and compare the 2 readings. this should rule out any fault wether the TC is dead, or the TC board is dead.

[mm_build 1]

you might have killed your TC board... (you really did measure only 20mV, not 200mV?)

Yep, twenty not 200.

I heated up the nozzle in Pronterface (haven't managed to break the heater ..yet), it got nice and hot. The voltage measured ~50mV before heating, and the same after. The situation was the same where the longer I held the multimeter to the contact points, the lower the voltage would drop. It went down to 30mV in a matter of about 20 seconds. *sigh*

If you disconnect the red/orange TC wires from the TC board, and measure the voltage between the 2 wires, you should see about 0.7mV at room temp, and if you heat the TC up a bit (hairdryer) to 60-70C, you should see about 2-3mV... this requires a good multimeter... if your multimeter has a temp function and you have a TC that came with it, you can 1st hook up this TC, and see what temp and voltage it is giving you. then hook up the orange/red wires of the UM TC to your multimeter, and compare the 2 readings. this should rule out any fault wether the TC is dead, or the TC board is dead.

I hooked up the TC that came with my multimeter and put the hot air dryer on it, The temp was anywhere between about 50-90C with the voltage between 1.5-2.5mV. (Hard to measure because it cools down so quickly). I unscrewed the wires from the TC on the UM and put the dryer to the aluminum block. At about 65C I was measuring about 1.7 mV. I let it cool a bit, and at about 51C I was measuring about 1.2mV.

These tests lead me to believe that there is nothing wrong with my Arduino or TC. Does this mean the chip on my TC PCB is blown? I read on the back what looks like "AD597", can I simply buy a replacement chip and solder it in? Or is there something else I should be doing to confirm the problem?

Thanks for all your help by the way!

[joergen 2]

Yes, it might be that the AD597 died... For whatever reason...

I would suggest to take off the TC board completely, and inspect it under a loupe of microscope for any dry solder joints, and cracks... If you can, resolder everything that looks suspicious... I think replacing the AD597 is possible, but requires quite a bit of soldering skills... I certainly couldn't do that... I hate SMB parts, they are too small for my taste.

[mm_build 1]

Yes, it might be that the AD597 died... For whatever reason...

I would suggest to take off the TC board completely, and inspect it under a loupe of microscope for any dry solder joints, and cracks... If you can, resolder everything that looks suspicious... I think replacing the AD597 is possible, but requires quite a bit of soldering skills... I certainly couldn't do that... I hate SMB parts, they are too small for my taste.

Well I know what I am up against now. I am no expert at soldering, probably one of the worst, but I bet I can get it right if I have to. I will update this space when I have my new chip. If that doesn't work out I will consider replacing the TC PCB, and if that doesn't work out, well there's only so many parts to replace. Thanks again!

[Daid 306]

I think replacing the AD597 is possible, but requires quite a bit of soldering skills... I certainly couldn't do that... I hate SMB parts, they are too small for my taste.

SMD, not SMB (SMB = SuperMarioBros :mrgreen: )

The AD597 comes packaged in one of the largest SMD packages available, which is quite solderable, with proper equipment. However, it might have been soldered lead-free with is a bitch to solder by hand. Try to remove the old chip first to see how wel it goes.

BUT, first see if there are any bad solder connections, one of the SMD pins might be floating above it's pad, not making contact. Sometimes SMD pins disconnect after fabrication because they where badly soldered. If you have a good soldering iron then you could solder down each leg with a tiny bit of extra solder.

Also check the connector pins, they have had bad solder on connector pins on the main board so might also be possible that you have a bad solder there.

[mm_build 1]

I have not had much time to play with this lately, but I finally replaced the AD597 and did some testing.

The AD597 chip itself appears to be functioning correctly, however I am still getting a bogus signal. Measuring voltage between pins 5/6 and ground, the output appears to be bang-on correct to 10mV/C. Heating the extruder in pronterface and measuring the voltage at the pins shows that the mV are increasing and decreasing proportionally to the temperature.

The problem is that when I measure from the green signal wire (where pins 5 and 6 lead to), the voltage is pretty random. I am measuring anywhere between .45 and 4.5 volts at the signal wire. It seems to change when I reset the machine, and it seems to be totally random. However, this voltage reading is consistent with the temperature reading in pronterface. For example, when the voltage is about 4.5, I will get a temp reading of about 450 degrees.

The voltages in the signal wire are not coming from the TC board. I completely unplugged the TC board and measured the signal pin on the main PCB, and the voltage was the same. Am I supposed to be getting random voltages from this pin at the PCB side? And if not any tips for what next?

Thanks.

[mr_seeker 0]

I have not had much time to play with this lately, but I finally replaced the AD597 and did some testing.

The AD597 chip itself appears to be functioning correctly, however I am still getting a bogus signal. Measuring voltage between pins 5/6 and ground, the output appears to be bang-on correct to 10mV/C. Heating the extruder in pronterface and measuring the voltage at the pins shows that the mV are increasing and decreasing proportionally to the temperature.

The problem is that when I measure from the green signal wire (where pins 5 and 6 lead to), the voltage is pretty random. I am measuring anywhere between .45 and 4.5 volts at the signal wire. It seems to change when I reset the machine, and it seems to be totally random. However, this voltage reading is consistent with the temperature reading in pronterface. For example, when the voltage is about 4.5, I will get a temp reading of about 450 degrees.

So, where do you get the bogus signal? At the PCB connector or at X2-1?

[mm_build 1]

So, where do you get the bogus signal? At the PCB connector or at X2-1?

Both places, X2-1 when the signal wire is connected to the main PCB. When the signal wire is disconnected, it's only at the main PCB connector.

The "bogus signal" does not appear to travel backwards to the pins on the AD597, for whatever reason.

[mm_build 1]

SUCCESS-ish!

Since the voltage at X2-1 was different from the voltage at pins 5/6, I thought perhaps there was a break or a short or something. Well, I directly soldered pins 5/6 to X2-1 with a bit of wire, and the result so far is desirable.

My machine is reporting accurate temperatures for the first time since the trouble began. I still don't know what the phantom voltage coming from PCB side was, but connecting directly to pins 5 and 6 seems to override whatever was coming off the main PCB. Perhaps it was a signal used to search for the AD597? At any rate things are moving forward now, I will update if I encounter any more problems.