Duex2 fan outputs going mad

RandomFactoid

Hi,

I am having issues with my Duex2 which I bought a long time second-hand (i.e. it's not the latest version board..mine says Duex5 V0.6). Photo of the board here: https://photos.app.goo.gl/rjVUtv8GfXj3SCFm7

Currently I have fan outputs used connected as follows:

Fan4 has a thermostatically controlled hotend fan (M106 P4 T60 H1 S255)
Fan5 has part fan (M563 P0 S"Hotend1" D0 H1 F5 and M106 S0)
Fan6 and Fan7 have LED strips.

Issues:

Fan3 is showing ~8.5 volts when on. Clearly something's broken..somewhere. Any clues where to start looking for problems ?
For some reason both Fan 5 and Fan6 (e.g. M106 P5 or P6) both control the part fan - as if their PWM overlaps. Interestingly if I set them both to a certain value, switching one off still runs the fan at a value of the other fan pins. Also dimming my LEDs connected to Fan6 doesn't work - it only controls the part fan. LEDs connected to Fan7 dim fine (e.g. M106 P7 S100).

Attaching my config.g:

G21 ; millimeter units
G90 ; absolute tool coordinates
M83 ; relative extruder coordinates

;; geometry ------------------------------------------------

M667 S1 ; corexy mode
M208 X0 Y0 Z0 S1 ; S1 = set axes minima
M208 X245 Y253 Z250 S0 ; S0 = set axes maxima
M574 X2 Y2 Z2 S0 ; endstops

M557 X25:225 Y25:225 S50 ; configure z probing grid for mesh compensation
; (not used normally, but configures probing for the graphical bed report)

M98 P"/macros/zprobe/use_mfast.g"
M98 P"/macros/zprobe/use_ifast.g"

;; drive ---------------------------------------------------

;; Motor layout:
;; E0 E1
;; YB XA
;; Z2 Z3
;; Z0 Z1

;;----------------
;V2.1

M584 X3 Y4 Z5:2:1:6 E0 ; motor bindings RCF
M671 X-58:-58:297:297 Y-5:341:341:-5 S15 ; Z drive positions RCF

;;--------------------

;M584 X3 Y4 Z2:1:6:5 E0 ; motor bindings RCF
;M584 X3 Y4 Z2:5:1:6 E0 ; motor bindings
;M671 X-57:-57:312:312 Y-17:308:308:-17 S15 ; Z drive positions RCF

;M671 X-57:312:-57:312 Y-17:-17:308:308 S15 ; Z drive positions

M569 P3 S1 ; X motor direction
M569 P4 S1 ; Y motor direction
M569 P1 S1 ; Z-- motor direction
M569 P2 S0 ; Z+- motor direction
M569 P5 S1 ; Z-+ motor direction
M569 P6 S0 ; Z++ motor direction
M569 P0 S1 ; E0 motor direction
;M569 P4 S1 ; E1 motor direction
;M569 P2 S1 ; E2 motor direction

M84 S3600 ; motor idle timeout
M906 I50 ; motor idle current percentage
M350 X16 Y16 Z16 E16 I0 ; set microstepping
;M92 X160 Y160 Z320 E604 ; set microsteps per mm for 0.9-degree steppers
;M92 X80 Y80 Z400 E263 ; set microsteps per mm for 1.8-degree steppers (Mobius1)
M92 X80 Y80 Z400 E534 ; set microsteps per mm for 1.8-degree steppers (Mobius2)
;M92 X80 Y80 Z160 E160 ; set microsteps per mm for 1.8-degree steppers

;; velocity, acceleration, and current settings are in these macros
M98 P"/macros/drive/xy_fullcurrent.g"
M98 P"/macros/drive/z_fullcurrent.g"
M98 P"/macros/drive/e_fullcurrent.g"

;; firmware retraction -------------------------------------

;; Choose one as your default:
;M98 P"/macros/retraction/quiet_nozhop.g
M98 P"/macros/retraction/quiet_zhop.g
;M98 P"/macros/retraction/pa_nozhop.g"
;M98 P"/macros/retraction/pa_zhop.g"

;; thermal -------------------------------------------------

M305 P0 X0 R4700 T100000 B3950 ; bed thermistor
M143 H0 S136 ; bed cutoff temp
M570 H0 T15 S180 ; heater fault timeout
M140 S-999 R0

M305 P1 R4700 T100000 B3950 ; tool 0 thermistor
M143 H1 S280 ; tool 0 temp cutoff
M570 H1 T15 S120 ; heater fault timeout

M305 P103 X2 S"Keenovo" R4700 T100000 B3950
M143 P100 H0 X103 A0 C0 S145

;M305 P2 R4700 T100000 B4267 ; tool 1 thermistor
;M143 H2 S280 ; tool 1 temp cutoff
;M570 H2 T10 S120 ; heater fault timeout

M106 P7 S0.2 ;Hotend LED
M106 P5 S0 ; part fan
M106 P4 T60 H1 S255 ; hotend fan
;M106 P2 S0 ; enclosure fan
;M106 P6 S1.0

;; M303 H1 S235 ; run autotune
;; M500 to save autotune results to config-override.g,
;; then move the heater config lines from config-override.g here.
;; (Delete them from config-override.g, or you will be confused when changing this file doesn't work.)
M307 H0 A300.4 C567.1 D1.2 S1.00 V24.1 B0
M307 H1 A473.4 C206.5 D9.1 S1.00 V24.1 B0

;; tools ---------------------------------------------------

M563 P0 S"Hotend1" D0 H1 F5 ; bind tool 0 to drive and heater
G10 P0 X0 Y0 Z0 ; tool offset
G10 P0 S0 R0 ; tool active and standby temp

;M563 P1 D1 H2 ; bind tool 1 to drive and heater
;G10 P1 X0 Y0 Z0 ; tool offset
;G10 P1 S0 R0 ; tool active and standby temp

;M572 D0 S0.1 ;Pressure Advance

M501

T0 ; activate tool 0

dc42

The most common problem we see with older DueX boards is imperfect soldering between the SX1509B chip and the PCB. the pads are under the chip, so it's not possible to inspect the solder joints other than by using X-rays. That could explain all the problems, although the Fan 3 problem might also be caused by a blown mosfet.

Replacing the SX1509B or just reflowing the existing one using hot air rework equipment may fix the problems.