@dc42 Thanks for your help, David. Okay, I measured R19 and R53. They both give me 4.7K and from reading the resistors that is correct.
I also checked out the resistors for the thermisters3-7 and they all show 10K which checks out.

So I checked the traces for ADVREF and found the problem. I found a ~4M ohm resistance on the trace which explains a lot of the behaviour I've been observing. Would explain why I was still getting a 3.3V that dropped down to 0.15Volts as I measured it.

I have not yet pinpointed the bad trace though. I've stared at the board till my eyes bleed and I spotted no burn marks or scratches that would indicate the area. Just that it's fine up until the expansion header pin. From there I see goes to the bed thermistor resistor. Which is also fine.

So any suggestions where I could try to run a wire to skip over the bad trace?
No way I can solder to a side of any of those resistors. I don't have a scope, steady hand, and the skills to do something like that.

I was thinking I could start it on the back at the ADVREF pin on the expansion header and then solder to something big enough to try to see if that would jump the bad spot and get my board finally working.

Thanks

For the Duet2 pcb 1.04c

Okay so here's the problem.
None of the thermistor connectors work accept the one for measuring the bed temperature.
It was a difficult problem for me to diagnose because at first I thought that the problem was with the actual thermistors I tried.

What is happening is that the voltage starts off at 3.3V on the open pins. But it immediately starts to drop and will settle down to about 0.15 volts over a period of 5mins or so.

The pins for thermistor0 read at 3.3Volts.
All the others including the expansion pins have the voltage drop problem.
I've downloaded the pcb file to look at the board using KiCad but I can't figure out where the problem might be.
What I noticed was that thermistor0 is getting voltage from ADVREF but the other thermistors don't seem to have that in their connections.

So I'm not sure where to go with this.
I think it might be a bad capacitor but that's just a half educated guess. Just because of the way the voltage does the slow drain.

So I want to know is problem happened before?
Is there a single point on the board where there might be a chip that's gone bad?
Or is it actually at the Atmel CPU?
How can I narrow down the area where the problem might be?
I've noticed a fuse (F1) in the schematics but I'm not so sure that's the problem because one thermistor works.
I do not have hands steady enough to measure individual pins coming out of the Atmel but from the way a thermistor circuit is supposed to be designed I seriously think the source voltage is the problem anyway.

As for my knowledge I learned circuit and board design back in college (25 years ago) but I could only design the most basic of boards right now.

Anyone have an ideas be much appreciated.
Thanks

Daniel

Its got to be the E0 E1 sensors on the board somewhere. The bed sensor works fine.

I bought the Duet about 6 months ago. I had tried to install it then but it failed to work so shelved it until now.

The printer didn't come with a heated bed.
Yeah, I've tried other thermisters. Just try a couple of new ones I dug up. Same problem.

But I haven't tested it using the bed temperature pins instead. I'll try that.

@Phaedrux Gotcha

; Configuration file for Duet WiFi (firmware version 3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.1.4 on Tue Oct 20 2020 15:34:09 GMT-0700 (Pacific Daylight Time)

; General preferences
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"My Printer" ; set printer name

; Network
M552 S1 ; enable network
M586 P0 S1 ; enable HTTP
M586 P1 S0 ; disable FTP
M586 P2 S0 ; disable Telnet

; Drives
M569 P0 S1 ; physical drive 0 goes forwards
M569 P1 S1 ; physical drive 1 goes forwards
M569 P2 S1 ; physical drive 2 goes forwards
M569 P3 S1 ; physical drive 3 goes forwards
M584 X0 Y1 Z2 E3 ; set drive mapping
M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
M92 X89.27 Y89.27 Z400.00 E420.00 ; set steps per mm
M566 X900.00 Y900.00 Z12.00 E120.00 ; set maximum instantaneous speed changes (mm/min)
M203 X12000.00 Y12000.00 Z7200.00 E2400.00 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z50.00 E250.00 ; set accelerations (mm/s^2)
M906 X1000 Y1000 Z1000 E1200 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 X0 Y0 Z0 S1 ; set axis minima
M208 X210 Y160 Z220 S0 ; set axis maxima

; Endstops
M574 X1 S1 P"xstop" ; configure active-high endstop for low end on X via pin xstop
M574 Y1 S1 P"ystop" ; configure active-high endstop for low end on Y via pin ystop
M574 Z1 S1 P"zstop" ; configure active-high endstop for low end on Z via pin zstop

; Z-Probe
M558 P0 H5 F120 T6000 ; disable Z probe but set dive height, probe speed and travel speed
M557 X15:210 Y15:160 S20 ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0 ; map heated bed to heater 0
M143 H0 S120 ; set temperature limit for heater 0 to 120C
M308 S1 P"e1temp" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin e1temp
M950 H1 C"e1heat" T1 ; create nozzle heater output on e1heat and map it to sensor 1
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit

; Fans
M950 F0 C"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H1 T200 ; set fan 0 value. Thermostatic control is turned on
M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency
M106 P1 S0.75 H1 T150 ; set fan 1 value. Thermostatic control is turned on
M950 F2 C"fan2" Q500 ; create fan 2 on pin fan2 and set its frequency
M106 P2 S0.75 H1 T150 ; set fan 2 value. Thermostatic control is turned on

; Tools
M563 P0 D0 H1 F0 ; define tool 0
G10 P0 X0 Y0 Z0 ; set tool 0 axis offsets
G10 P0 R0 S0 ; set initial tool 0 active and standby temperatures to 0C

; Custom settings are not defined

The thermistor is some cheap part that came with the machine. Generic settings of 100K worked fine.

The Heater fault is caused by the high temp sensed.
Oh leaving the E0 pins in an open state causes the temp to start at approx 40C and slowly climb up. My first guess is a capacitor charging. But without a board schematic.

;---------------------------------------------------------------------------------------------------------------------------------
M98 P"config.g"
HTTP is enabled on port 80
FTP is disabled
TELNET is disabled
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 365C

Error: Heater 1 fault: heater monitor 0 was triggered
;---------------------------------------------------------------------------------------------------------------------------------
M122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 3.1.1 running on Duet WiFi 1.02 or later
Board ID: 08DGM-917DA-G4MS8-6JKD2-3S46Q-TTT3B
Used output buffers: 3 of 24 (11 max)
=== RTOS ===
Static ram: 27980
Dynamic ram: 93740 of which 44 recycled
Exception stack ram used: 272
Never used ram: 9036
Tasks: NETWORK(ready,384) HEAT(blocked,848) MAIN(running,1824) IDLE(ready,80)
Owned mutexes: WiFi(NETWORK)
=== Platform ===
Last reset 00:07:28 ago, cause: power up
Last software reset at 2020-10-20 15:36, reason: User, spinning module GCodes, available RAM 9748 bytes (slot 2)
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0441f000 BFAR 0xe000ed38 SP 0xffffffff Task MAIN
Error status: 0
MCU temperature: min 21.8, current 30.8, max 31.2
Supply voltage: min 23.9, current 24.1, max 24.3, under voltage events: 0, over voltage events: 0, power good: yes
Driver 0: standstill, SG min/max not available
Driver 1: standstill, SG min/max not available
Driver 2: standstill, SG min/max not available
Driver 3: standstill, SG min/max not available
Driver 4: standstill, SG min/max not available
Date/time: 2020-10-20 20:21:11
Cache data hit count 774144141
Slowest loop: 7.20ms; fastest: 0.13ms
I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0, resets 0
=== Storage ===
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest read time 3.6ms, write time 0.0ms, max retries 0
=== Move ===
Hiccups: 0(0), FreeDm: 169, MinFreeDm: 169, MaxWait: 0ms
Bed compensation in use: none, comp offset 0.000
=== MainDDARing ===
Scheduled moves: 0, completed moves: 0, StepErrors: 0, LaErrors: 0, Underruns: 0, 0 CDDA state: -1
=== AuxDDARing ===
Scheduled moves: 0, completed moves: 0, StepErrors: 0, LaErrors: 0, Underruns: 0, 0 CDDA state: -1
=== Heat ===
Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1 -1 -1
=== GCodes ===
Segments left: 0
Movement lock held by null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
Daemon is idle in state(s) 0
Autopause is idle in state(s) 0
Code queue is empty.
=== Network ===
Slowest loop: 15.69ms; fastest: 0.00ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0), 0 sessions
HTTP sessions: 1 of 8

• WiFi -
  Network state is active
  WiFi module is connected to access point
  Failed messages: pending 0, notready 0, noresp 0
  WiFi firmware version 1.23
  WiFi MAC address 60:01:94:2e:1b:e8
  WiFi Vcc 3.39, reset reason Unknown
  WiFi flash size 4194304, free heap 21480
  WiFi IP address 192.168.0.26
  WiFi signal strength -67dBm, reconnections 0, sleep mode modem
  Socket states: 4 0 0 0 0 0 0 0

[0_1603250781513_config (2).txt](Uploading 100%)

Hello,

Got a problem with the readings from my extruder head. It's currently fluctuating between 790-900C on the web UI display and but the temperature is slowly climbing. The fluctuations are still over a wide 100C+ range. I'm running out of things to check. I've swapped between both E0 and E1 pins and both have the same problem. Yes changed the configuration when I swapped pins.
There is 0 power going to the heater. And a manual test shows it's still at ambient temp.

I've triple checked the Thermistor and it's fine. The ambient temperature is 19C and the resistance is at ~124K. There is very little fluctuation with that measurement. Just your standard changes you'd expect with noise, etc.
Checked the fuses which were fine. Still, replaced them with new ones. Which are also good.
Ohm'd the VSSA pin to ground and it's around 1 ohm.

The Duet3D v2 wifi is being installed into an old cartesian printer oh mine. The thermistor was working fine before I pulled the Arduino/Mega brains.
Duet version 2.03 firmware but I upgraded to 3.1.1 trying to troubleshoot.
Under 2.03 firmware I ran M305 commands to try to correct.
I don't expect M308 commands to be any different.
That temperature is too high. It can't be corrected.
And the slowly climbing temp tells me that it's more than just correcting it with thermistor offsets.

All the steppers and end stops are working so I don't think it's a power source problem.

Any suggestions?

Thanks