Replaced hot end and now get vssa fault

[Veti]

just making sure the thermistors is normally in the heater block?

[chriskimbr]

@veti the thermistor is in block when i power on yes.

I assume i check ohms on thermistor with it out?

Do i choose auto, kohms or Mohms?

With thermistor out and multimeter on ohms auto i read 106.1

With multimeter at Mohms i read 0.104

[chriskimbr]

@chriskimbr Is this a good reading or a bad reading?

I don't know much about electronics. Please advise.

[Veti]

@chriskimbr said in Replaced hot end and now get vssa fault:

Do i choose auto, kohms or Mohms?

100k is about right for the thermistor

what is the temperature reading when you turn on your duet?

[chriskimbr]

@veti

[chriskimbr]

[chriskimbr]

@veti see pics

bed is 24 degrees but hot end is 2000.C which is fault.

[Veti]

do replace the connector with a proper molex plug.

check that there is no connection between the thermistor and the heater block/heater element.

[chriskimbr]

@veti Are you saying replace the connector to the thermister e-temp 0 ?
What is a correct Molex connector for it?

[chriskimbr]

I replaced the stock Tronxy X5SA hot end with the v6 clone above.
Ohm reading for new thermistor is 106.

Would these settings above need to change for the next thermistor / hot end?
Would this be causing the VSSA fault reading 2000.0C ?

config.g file section for
; Heaters
M305 P0 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 0
M143 H0 S120 ; Set temperature limit for heater 0 to 120C
M305 P1 T100000 B4388 C7.060000e-8 R4700 ; Set thermistor + ADC parameters for heater 1
;M305 P1 R4700 T100000 B4388 ; set E0 thermistor parameters
M143 H1 S280 ; Set temperature limit for heater 1 to 280C

[Veti]

@chriskimbr said in Replaced hot end and now get vssa fault:

What is a correct Molex connector for it?

the correct connector came with the duet. its the 2 pin one.

@chriskimbr said in Replaced hot end and now get vssa fault:

M305 P1 T100000 B4388 C7.060000e-8 R4700

where did you get those values from?

@chriskimbr said in Replaced hot end and now get vssa fault:

Would this be causing the VSSA fault reading 2000.0C ?

no the cause for that is faulty wiring or a blown vssa fuse.

[chriskimbr]

@veti

Is this the correct connector?

Regarding my setting...
M305 P1 T100000 B4388 C7.060000e-8 R4700

Got the settings from someone else with same printer.

What needs to be changed?

[Veti]

@chriskimbr said in Replaced hot end and now get vssa fault:

Got the settings from someone else with same printer.

but you switched the thermistor. you need the settings that fit your thermistor.
you can calculate the values from the thermistor table that you hopefully got with the hotend.

[chriskimbr]

@veti The hot end with thermistor came with no documentation.

[Veti]

then you prob need to either

• measure the resistance at 50 and 240 degrees using a calibrated temperature sensor.
• buy a thermistor with documentation
• live with inaccuracies that could range around 40 degrees

[chriskimbr]

@veti Im going to get a cheap hot end and thermistor from local store to test and see if im having same problem.
from what your telling me , i need to look at thermisor table and set the 'C' value ?

[Veti]

you can use the configurator tool to calculate the values

https://configurator.reprapfirmware.org/Heaters

[chriskimbr]

@veti so the setting for thermistor isnt causing the vssa fault?

[Veti]

wrong B and C values will just give you wrong temperature reading. 2000 means there is no reading

[dc42]

The Vssa fault message means that the Vssa line, which should be very close to ground potential, is actually closer to +3.3V.

The usual cause of this is a short between the side of the thermistor that is connected to Vssa, and the hot end heater or bed heater. So if you get a Vssa fault report, disconnect the thermistors one at a time. Then you will be able to tell which thermistor has the short to a heater.

If you disconnect all the thermistors and you still get the Vssa fault, then either the Vssa polyfuse is open circuit, or the Vssa sense series resistor is open circuit.