hello everybody 
i received and assembled my sv 08 max a few days ago, but the only thing i get after startup is a message ‘‘mcu buffer_mcu : Unable to connect’’ and i am at a loss. i checked all the reachable connectors, unplugged and replugged them, and looked for an input voltage switch (i could not find one, here in germany it would have to be set to 230 v). can anyone pls. get me into the right direction or help me fix this ? thank you all very much in advance
It appears the power supply is “self switching”.
Do you have network connection (wired or wifi) to the printer?
hello, thanks for your reply. ok, the input voltage isn’t causing the problem, then.
yes, the printer is connected to ethernet/lan (and i checked the connection with a notebook, dhcp works, internet is available)
You shoud open a support ticket. Email info@sovol3d.com. Include your order number.
While you are waiting for a reply you can try the following:
Put the printer IP in your browser. Does Mainsail show up?
Find your MCU
Query devices | Mainsail.
Then go to the [Machine] tab and click on printer.cfg to open it in Mainsail’s built in editor. Edit printer.cfg with the correct address, save and restart.
OR connect with Putty (or ssh ap of your choice)
User sovol
Password sovol
thank you very much again, for your help
i emailed the support, and via their fb-messenger. i have no order no. - i bought the printer on the sovol kickstarter campaign as early bird offer. i have a few emails from kickstarter/pledgebox, and of course the visa invoice with the purchase (kickstarter com chung hk 915.46 eur) but nowhere there is a order no. to be found. my backer no. is 455 
yep, mainsail is coming up - and now i have to make a confession. i come from a anet a8, e10, anycubic i3 mega, a prusa mk3s now 3.9, a bambulab x1c and prusa xl 2t. i finished building a fystec voron 2.4 kit in november, but i am too dumb to get the software running, so i am a complete newbie regarding klipper
following the printer.cfg of the sv 08 max - but i have no idea what adress i have to change ???
[include mainsail.cfg]
#[include chamber_hot.cfg]
[include buffer_stepper.cfg]
[include timelapse.cfg]
[include plr.cfg]
[include Macro.cfg]
[include moonraker_obico_macros.cfg]
[mcu]
canbus_uuid: 0d1445047cdd
[mcu extra_mcu]
canbus_uuid: 61755fe321ac
[temperature_sensor mcu_temp]
sensor_type: temperature_mcu
min_temp:0
max_temp:110
[temperature_sensor Host_temp]
sensor_type: temperature_host
min_temp: 0
max_temp: 110
[temperature_sensor Toolhead_Temp]
sensor_type: temperature_mcu
sensor_mcu: extra_mcu
[virtual_sdcard]
path:/home/sovol/printer_data/gcodes/
[exclude_object]
[printer]
kinematics: corexy
max_velocity: 700
max_accel: 40000
max_accel_to_decel: 10000
max_z_velocity: 10
max_z_accel: 500
square_corner_velocity: 5.0
[lis2dw]
cs_pin: extra_mcu:PB12
spi_software_sclk_pin: extra_mcu:PB13
spi_software_mosi_pin: extra_mcu:PB15
spi_software_miso_pin: extra_mcu:PB14
axes_map: x,z,y
[resonance_tester]
accel_chip: lis2dw
probe_points:
250, 250, 30
accel_per_hz:100
min_freq: 35
max_freq: 45
max_smoothing: 0.25
hz_per_sec: 1.0
[input_shaper]
damping_ratio_x: 0.001
damping_ratio_y: 0.001
[probe_eddy_current eddy]
sensor_type: ldc1612
z_offset: 3.50
i2c_mcu: extra_mcu
i2c_bus: i2c2
x_offset: -19.8
y_offset: -0.75
vir_contact_speed: 3.0
[bed_mesh]
speed: 400
horizontal_move_z: 1.5
algorithm: bicubic
mesh_min: 13,15
mesh_max: 476,490
probe_count: 60,60
fade_start: 0
fade_end: 10
scan_overshoot: 4
[z_offset_calibration]
non_contact_probe:probe_eddy_current eddy
contact_probe:probe_eddy_current eddy
endstop_xy_position: 250,251
z_hop: 5
z_hop_speed: 10
internal_endstop_offset: -0.25
[quad_gantry_level]
gantry_corners:
-70,-40
550,600
points:
50, 30
50, 470
490, 470
490, 30
speed: 400
horizontal_move_z: 10
retry_tolerance: 0.1
retries: 15
max_adjust: 20
[safe_z_home]
home_xy_position: 277,251
speed: 150.0
z_hop: 10
z_hop_speed: 10.0
[stepper_x]
step_pin: PE1
dir_pin: PD7
enable_pin: !PD5
rotation_distance: 40
microsteps: 16
full_steps_per_rotation: 200
endstop_pin: ^extra_mcu:PA10
position_min: -11
position_endstop: -11
position_max: 502
homing_speed: 120
homing_retract_dist: 3
homing_retract_speed: 15.0
[tmc5160 stepper_x]
cs_pin: PE0
spi_software_mosi_pin: PB6
spi_software_miso_pin: PB5
spi_software_sclk_pin: PB4
interpolate: false
run_current: 3.0
sense_resistor: 0.05
stealthchop_threshold: 0
[stepper_y]
step_pin: PD3
dir_pin: PD2
enable_pin: !PD0
rotation_distance: 40
microsteps: 16
full_steps_per_rotation: 200
endstop_pin: ^PD1
position_min: -1
position_endstop: 505
position_max: 505
homing_speed: 120
homing_retract_dist: 3
homing_retract_speed: 15.0
[tmc5160 stepper_y]
cs_pin: PD4
spi_software_mosi_pin: PB6
spi_software_miso_pin: PB5
spi_software_sclk_pin: PB4
interpolate: false
run_current: 3.0
sense_resistor: 0.05
stealthchop_threshold: 0
[stepper_z] #z1
step_pin: PA8
dir_pin: PC9
enable_pin: !PA10
rotation_distance: 40
gear_ratio: 80:12
microsteps: 16
endstop_pin: probe: z_virtual_endstop
position_max: 505
position_min: -10
homing_speed: 10.0
homing_retract_dist: 5.0
homing_retract_speed: 10.0
second_homing_speed: 5.0
[tmc2209 stepper_z]
uart_pin: PA9
interpolate: true
run_current: 1.2
sense_resistor: 0.150
uart_address:3
stealthchop_threshold: 999999
[stepper_z1] #z2
step_pin: PC6
dir_pin: !PD15
enable_pin: !PC8
rotation_distance: 40
gear_ratio: 80:12
microsteps: 16
[tmc2209 stepper_z1]
uart_pin: PC7
interpolate: true
run_current: 1.2
sense_resistor: 0.150
uart_address:3
stealthchop_threshold: 999999
[stepper_z2] #z3
step_pin: PA5
dir_pin: PA4
enable_pin: !PA7
rotation_distance: 40
gear_ratio: 80:12
microsteps: 16
[tmc2209 stepper_z2]
uart_pin: PA6
interpolate: true
run_current: 1.2
sense_resistor: 0.150
uart_address:3
stealthchop_threshold: 999999
[stepper_z3] #z4
step_pin: PB13
dir_pin: !PB12
enable_pin: !PB15
rotation_distance: 40
gear_ratio: 80:12
microsteps: 16
[tmc2209 stepper_z3]
uart_pin: PB14
interpolate: true
run_current: 1.2
sense_resistor: 0.150
uart_address:3
stealthchop_threshold: 999999
[adc_temperature extruder_thermistor]
temperature1:25
resistance1:1268.60
temperature2:180
resistance2:1920.98
temperature3:300
resistance3:2398.52
[extruder]
step_pin: extra_mcu:PA8
dir_pin: extra_mcu:PA9
enable_pin:!extra_mcu:PA11
rotation_distance: 6.5
microsteps: 16
full_steps_per_rotation: 200
nozzle_diameter: 0.400
filament_diameter: 1.75
max_extrude_only_distance: 150
max_extrude_cross_section: 60
heater_pin:extra_mcu:PB7
sensor_type:extruder_thermistor
pullup_resistor: 11500
sensor_pin: extra_mcu:PA5
min_temp: -0
max_temp: 310
max_power: 1.0
min_extrude_temp: 150
control : pid
pid_kp : 34.838
pid_ki : 4.976
pid_kd : 62.823
pressure_advance: 0.025
pressure_advance_smooth_time: 0.035
[tmc2209 extruder]
uart_pin: extra_mcu:PA12
interpolate: True
run_current: 0.8
uart_address:3
sense_resistor: 0.150
[verify_heater extruder]
max_error: 120
check_gain_time:30
hysteresis: 10
heating_gain: 2
[thermistor bed_thermistor]
temperature1: 25
resistance1: 100000
temperature2: 50
resistance2: 18085.4
temperature3: 100
resistance3: 5362.6
[heater_bed]
heater_pin: PD12
sensor_type: bed_thermistor
sensor_pin: PC5
max_power: 1.0
min_temp: -0
max_temp: 110
control : pid
pid_kp : 73.571
pid_ki : 1.820
pid_kd : 783.849
[verify_heater heater_bed]
max_error: 120
check_gain_time: 90
hysteresis: 10
heating_gain: 1
[fan_generic fan0] # front model cool fan
pin: extra_mcu: PB0
max_power: 1.0
[fan_generic fan1] # back model cool fan
pin: extra_mcu: PA7
max_power: 1.0
[fan_generic fan2] # auxiliary fan
pin: PB0
max_power: 1.0
[fan_generic fan3] # exhaust fan
pin: PE11
max_power: 1.0
[output_pin main_led]
pin: PD13
value: 1.0
[heater_fan hotend_fan]
pin: extra_mcu: PA6
max_power: 1.0
kick_start_time: 0.5
heater: extruder
heater_temp: 45
tachometer_pin:extra_mcu: PA1
tachometer_ppr: 1
tachometer_poll_interval: 0.0013
[heater_fan bed_fan]
pin: PE14
max_power: 1.0
kick_start_time: 0.5
heater: heater_bed
heater_temp: 35
tachometer_pin: PB10
tachometer_ppr: 2
tachometer_poll_interval: 0.001375
[gcode_arcs]
resolution: 1.0
[idle_timeout]
gcode: _IDLE_TIMEOUT
timeout: 1800
[save_variables]
filename =/home/sovol/printer_data/config/saved_variables.cfg
## <---------------------- SAVE_CONFIG ---------------------->
## DO NOT EDIT THIS BLOCK OR BELOW. The contents are auto-generated.
##
## [input_shaper]
## shaper_type_x = mzv
## shaper_freq_x = 44.8
## shaper_type_y = mzv
## shaper_freq_y = 39.4
#*#
Follow the instructions at the Mainsail link above
Your printer has 3 different MCUs. Each will have an address similar to
canbus_uuid: 0d1445047cdd
The mainboard MCU is referred to as mcu
The toolhead MCU extra_mcu
And the buffer (filament pusher) buffer_mcu
Note: the CAN address for the buffer_mcu is in the buffer_stepper.cfg file but still has to be correct.
The error you posted seems to be associated with the mainboard.
It is more likely that the MCU is not connected at all but it is still a good idea to try and find it with the Mainsail routine.
Does Mainsail find any can devices?
hello,
devices lists the following:
CAN0 KLIPPER 61755fe321ac
USB KLIPPER stm32h750xx CAN Adapter 1d50:606f
USB 2.0 Camera 32e6:9221
VIDEO V4L2 USB 2.0 Camera /dev/video0
as i understand this, only unassigned devices are shown, right ? so the ‘‘mcu extra_mcu’’ can not connect ? meaning wiring between toolhead board and mainboard has a problem ?
I think you are right.
In printer.cfg I’d comment out
[mcu extra_mcu]
canbus_uuid: 61755fe321ac
By putting a # in front of them. Save and restart.
The error message should to “missing pin” or some such.
WHOOPS
I just reread your original post
BUFFER is referring to the filament pusher NOT an internal software register…
Your issue is with the pusher not the toolhead
hello cardoc, the sovol support did reply to my error message, and they confirm that the auxiliary buffer is at fault, either the device or its connection to the mainboard are not working properly. they had me check all connections again, but that fixed nothing.
i googled some more and out-commented the line
[include buffer_stepper.cfg]
with a # in the printer.cfg, and now the machine ist starting. i have no idea if it will print or throw an error missing the axiliary buffer, but i will check. for now a managed a complete calibration, so things are lighten up
thank you so much for your kind help 
Glad to have helped.
Just wish I’d have picked up “buffer” was a device name not a generic software reference. Could have saved 2 days.
Don’t worry about that - i am so raw and new with Klipper that any help is greatly appreciated and i am in no hurry, my X1C and XL are working perfectly.
if i may, and not seem to be too intrusive, would you consider helping me getting my voron 2.4 (build is complete but for the software) to start printing ? if so, i happily offer a donation via paypal if that can be successfully completed and also no hurry in any way, the machine lies on its back behind me on a bench for 8 months now, i would have to dive in again before we can even start
Getting a Max to run with the buffer_mcu missing won’t be easy. The main printer.cfg is clean but MANY macros have calls to functions in buffer_stepper.cfg
M400, M600, PAUSE, LOAD_FILAMENT, UNLOAD_FILAMENT are all going to error.
oh, that is sad to hear - i will have to wait for sovol to send me a buffer unit or the buffer_mcu then
Sure but for that find me (and several MUCH more knowledgeable folks) on General Discussion - Klipper
NOTE to others. The folks at link that have a hard and fast rule about “dirty” forks of Klipper. Only post there if you are on “mainline”.
No charge, I’ll rely on karma to balance any debts.
Go in and rename macros.cfg to max_macros.cfg then upload the attached file from a “regular” SV08.
Don’t know if it’ll work but there is only one way to know.
Macro.cfg (19.6 KB)
i will, thank you - and wish you the best Karma
thats a great idea - i will try that tomorrow, tks.