Best posts made by oracledude

@rjenkinsgb
That change looks like it fixed the issue...

; Bed Heater
M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 A"Bed Heater"    ; 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 S0.90                                   ; use PID tuning for the bed heater and set PWM limit // CONFIG_OVERRIDE handles this
M140 H0                                            ; map bed to heater 0
M140 S25 R40                                       ; active/standby to 25/40.  turn off bed heater by setting to -273
M143 H0 S120                                       ; set temperature limit for heater 0 to 120C

; Hot End Heater
M308 S1 P"e0temp" Y"thermistor" T100000 B4138 A"Hot End"      ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1                               ; create nozzle heater output on e0heat and map it to sensor 1
;M307 H1 B0 S0.90                                   ; CONFIG_OVERRIDE handles this
M143 H1 S280                                       ; set temperature limit for heater 1 to 280C

; Tools
M563 P0 S"DeltaEffector" H1 F0 			   ; define tool 0 with heater 1 and Fan 0
M568 P0 R20 S25 A0                                 ; Set tool 0 Active/Standby=25C/20C/Off
G10 P0 X0 Y0 Z0                                    ; set tool 0 axis offsets

@dc42 No big deal, I've worked with smaller SMD packages before. WizNet W5500, 48LQFP. $4 at DigiKey. Beats having to buy another board, even if the Duet 3 Mini 5 looks really good.

The IC should be here in the next few days. I'll let you know how it goes.

@dc42 it really appeared that it's cycling at about 4Hz steadily, with or without the card in.

I unplugged all cables and actually traced the problem to something on the hot end, plugged into IO_1. Most likely the BL touch or the gyro. Unplugging that brought back the 1Hz blink and my fans powering up.

I should have checked the wiring first. Silly mistake.