Temperature T:0 B:0 on Gen3 Electronics...

Hi,

I hope all are well,

I have been having problems with my Reprap electronics recently with problems with the Y axis and temperature readout. After some help from forum user (Thanks ) I am now having trouble with my thermistor. I have little electronics experience and can't find a solution. Description below.

When the machine is started and connected to RepSnapper, there is an M105 command sent to the machine. I was previously receiving an accurate temperature reading, but now only get the following:

Sending:M105
Received:T:0 B:0 with Parameter 0 B:0
Received: ok EA with Paremeter EA**********************
Sending:M105
Received:T:0 B:0 with Parameter 0 B:0
Received: ok EB with Paremeter EB**********************

I think this is down to a loose connection somewhere but don't know where.

I have checked the thermistor connection and the resistance changes with changes in temperature. The temperature also increases when the heat is activated.

Any input or ideas on what to check would be appreciated.

Thanks to all.

Raj

With official firmware, thats the typical error you get when the extruder board is powered off. E.g. rs485 comm error cant find the extruder board slave mcu to talk to. Its a wonder that it heats up, it could be an an issue, since if they cant talk, then probably didnt got an instruction to do so in the first place (see if stuff heats up even without motherboard). Check rs485 leads and the 180R resistor should be only in one place, e.g. its on motherboard and on extruder board it should not be mounted.

In firmware for rs485 communication settings see the start of intercom.h, there should be same settings in both cases for extruder board firmware and for motherboard firmware, basically same things for both. If baud rate or buffer or some other stuff is different, then it wont talk properly.

Hi Noobman,

Thanks for your help. I'll check the firmware intercom.h files as you've outlined.

The thing which is confusing me is that at one point or another, the electronics have been functioning - Temperature readout, extruder/bed heat and fan.

At one point I was having problems with the Y axis and the temperature readout and after cleaning up the header pins, that's when it started to get 'weird'.

Sometimes i'd get a temperature readout and no Y axis movement and sometimes i'd get Y axis movement and no temperature readout.

I tried to upload the firmware onto the extruder board to see if this would help but i'm not sure if it uploaded successfully. I selected arduino diecimiela ATMEGA168 (probably a spelling mistake there) from the Arduino software (version18) and uploaded the firmware (loaded from Extruder.pde). Although the software said the upload was completed, i did not see the debug light flash as it does on the Motherboard.

I have also been looking at the components and descriptions on the RepRap wiki to get a better idea of what could be the problem.

I'm not sure of your knowledge of electronics (mine is poor) but could there be a problem with the SN75176A chips/connections on the motherboard/extruder.

Thanks

Raj

RepRapRaj83 Wrote:
-------------------------------------------------------
> Sometimes i'd get a temperature readout and no Y
> axis movement and sometimes i'd get Y axis
> movement and no temperature readout.

AFAIK one has nothing to do with the other, its weird, maybe the wires are too close and there is some crosstalk or even a short between some pins, but beyond that - nothing that could cause an issue like that that crosses my little head.

> I tried to upload the firmware onto the extruder
> board to see if this would help but i'm not sure
> if it uploaded successfully. I selected arduino
> diecimiela ATMEGA168 (probably a spelling mistake
> there) from the Arduino software (version18) and
> uploaded the firmware (loaded from Extruder.pde).
> Although the software said the upload was
> completed, i did not see the debug light flash as
> it does on the Motherboard.

Dunno if i recall correctly that firmare, but i think that debug lights up long like 3 sec and depends on rs485 talking. I dont think debug lights up at all if it cant connect to motherboard. Yes you selected right one - diecimila i think means two thousands Y2K in italian. Again check intercom.h settings in both motherboard and extruder firmwares to have same settings, baud, buffer and same error codes. Although if sometimes works and sometimes doesnt, that probably points to a hardware problem.

> I'm not sure of your knowledge of electronics
> (mine is poor) but could there be a problem with
> the SN75176A chips/connections on the
> motherboard/extruder.

Thats responsible for rs485 talking. There is one on each board, at each end of the two communication wires. However there should be only one 180 resistor. I remember now someone had a similar problem and was due to the purchased board having almost no solder on it - or barely any solder at all. Check your for solder, who knows. I think that thread should be somewhere in Electronics forum, and i think you should try find it - i dont recall specifics atm.

Hi Noobman,

Thanks again for the input.

RE: Axis/Temperature weirdness - I did check the Y axis header connections on the motherboard on the suspected 'faulty' motherboard against the connections on my working mendel to try and identify any shorts/broken connections, just in case anyone is interested, see sttached.

I couldn't spot any major differences in resistance between the two (measured in the 20K range) and i couldnt spot any differences in the connections between the pins which would suggest a short.

RE Firmware upload - I should have explained myself a little clearer in this. During firmware uploads on the motherboard, the 'debug' light flashes on/off rapidly for about 10 seconds. it then stops and begins to flash at the 'normal' rate of once every second.

When i uploaded firmware onto the extruder board, i only saw the 'debug' light flash when i connected the usb/ttl cable to my laptop, 6 flashes in all, 3 sets of two pairs which were split by noticeable spaces of time (o.o....o.o....o.o). During actual firmware upload, the light remained off although it did complete.

I'm going to ask some more possibly silly questions on the forum in order to get to the bottom of this. i'll put any findings on the forum to make sure no-one else has the same trouble.

Thanks again Noobman.

Raj

Hi all,

Further checks have confirmed it's a hardware problem - the problem (and solution) remains a mystery.

@Noobman - I first looked at the Intercom.h files on both boards – both had matching settings for communicating over the RS485 connection.
@Noobman – Checking for the R180 resistor on the motherboard (labelled R16 on the board itself), this is present. The R180 resistor on the Extruder (R1 reference) is not present.

I checked the faulty electronics by switching (one by one) the electronics on my working mendel with the ones with which i'm having trouble, this way if the printer stops working, i would know what part needs looking at.

I first checked the working printer - turned it on, connected it to my laptop and then made checks on axis movement, heater checks, fan activation and temperature readings - all working.

Started by replacing the extruder board, as above, turned it on, connected it and then looked at the readings, getting a reading of 13 degrees, accurate as I’m in an unheated room in England in November.
Extruder Board – off the hook.

Followed up by switching over the USB/TTL cable on the working reprap electronics just to make sure there were no problems with that.
USB/TTL cable - off the hook too.

Finally connected the motherboard to the working extruder board and USB/TTL cable. Powered it up and it was working???????????????????????

I was reading a temperature readout of 13 degrees and my axis were all moving. Truly stumped and inexpected!
It didn’t last long though. As soon as i moved the motherboard onto my MDF mounting sheet, it returned to a zero temperature readout and the y axis stopped working – again. Gone round in a big circle but at least i know what is at fault.

I'm suspecting this is due to a poor connection on the motherboard. As i keep on having trouble with my Y axis too – I’ve compared header connections on the faulty board against a working board which i HAVE attached this time.
As before, if anyone has any idea of what the problem could be, i’d be grateful for the input. Alternatively – If forum users would be so kind as to entertain/dismiss the possibilities below, this would also be helpful. For the electronics wizards out there,any info on how to test these in the most thorough manner would also be appreciated. Thanks

1. Excessive ‘Noise’ coming from the wiring around the motherboard.
2. A ground connection on the motherboard is loose resulting in temperamental behaviour through a charge being built up somewhere.
3. A broken connection/pin on the USB/TTL cable pins. I have checked the pins on the board and they look unbroken.
4. Pixies, Elves, the global economy etc.....

Thanks to all.

Raj

I think by default the motherboard has the "gnd" from usb cable alone, which isnt same gnd as the psu. The gnd from psu can come via stepper motor boards to the motherboard, and maybe that is not enough, maybe the switching steppers gives it extra noise too. Perhaps make sure to add an additional gnd from your psu to the motherboard itself - thats a standard recommendation with gen3. Use a good thick shorter wire than the others. There are two gnd pins to a corner of those headers near the mcu on mb12. Also same thing with the other boards including serial one if using that stuff, direct gnd to the psu of your mendel, not the psu of the computer.

Also if the mb works alone but when mounted it doesnt, perhaps re-melt and re-do the solder connections, check for the tht parts their leads, if when mounted its straight, if it makes a short, etc. Maybe its just a cold solder joint or something. If no solder iron / hot air station, at least try run the board with that stuff that dries your hair after you took a bath - set it to hottest and run it over board for a good time, closely, dont worry wont melt the solder, if its something like dirt, capacitors with water in them, etc, could help, although it doesnt do the proper job of a hot air station would. When it returns to 0 temp i think it means its loosing connection to extruder, but the mb still works since it does report the zero. So check extruder board and the wiring between too. Cant think of anything else that would help with a hardware issue.

Try a pull up on the RS485 A line and a pull down on B. These are missing on gen3 and mean that when the drivers are tri-state the receiver can be high or low. I suspect if it is low it will screw the comms.

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[www.hydraraptor.blogspot.com]

Noobman/Nophead,

Thank you both for your responses. I'll look at re-soldering the joints on the MB and adding additional ground connections.

@Nophead - Could you explain what you mean by trying a pull up on line A and a pull down on line B. Apologies but i'm unfamiliar with these terms.

Thanks again to you both. I will post any results/outcomes tomorrow.

Raj

A 1K5 resistor between the A line and 5V and between the B line and GND. With a single 180R terminator these will give a definite logic 1 between messages. Without them you could get logic 0 which will cause a flood of 00 with framing errors to be received between messages and may corrupt the first character of the message.

---

[www.hydraraptor.blogspot.com]

Yet more weirdness after going through some of the suggestions outlined.

After heating the boards up with a dryer and resoldering connections on the MB/EB, i tried my luck and connected up the boards. Partial success. The temperature reading was being returned and changed in line with when the heater was turned on and off.

Then came a check on the Y axis. Connected to Repsnapper, when a command is sent to move +/-1 unit of measurement, i hear a change in the sound coming from the stepper motor driver and also see the light sequence change around the stepper driver. I have checked the cable and stepper driver by connecting it to another axis and it works.

Would this be due to dirty/fluxed up connections or would it be more likely that this is a cold soldered connection/poor ground/high noise issue?

Any thoughts or suggestions would be welcomed.

Thanks and regards

Raj

I am not sure i get the current situation. I understand that basically everything works now except Y motor itself, so when you connect those outputs from the y stepper driver board to another motor then it works allright?

Perhaps it could be something with that motor - its connectors / wiring / or metal powder got into it when filing the shaft, etc?

Hi Noobman,

I should have explained myself better.

The Y Axis motor, ribbon cable and Y axis stepper driver work. I have checked this by testing the same parts by connecting them to both the x and z axis header on the motherboard. When the same parts are tested with inputs from the different axis, all works as expected.

I'm having a read of the wiki in order to get a better idea of the electronics and possible problem/solution. I will post any findings later.

Thanks

Raj