Attempt to move motors when VIN is not in range

Phaedrux

@Milke said in Attempt to move motors when VIN is not in range:

Supply voltage: min 21.3, current 22.2, max 24.9, under voltage events: 0, over voltage events: 0, power good: yes

At what point does it start to show the wrong voltage? As soon as you try to move a motor?

Milke

@Phaedrux said in Attempt to move motors when VIN is not in range:

At what point does it start to show the wrong voltage? As soon as you try to move a motor?

Now the voltage of My Power Supplay is 24 volts checked with multimeter and a voltage display. The DUet Web Contro, show me 13,2 Volts and M122: Error status: 0
MCU temperature: min 37.2, current 39.3, max 39.6
Supply voltage: min 12.2, current 14.1, max 14.6, under voltage events: 0, over voltage events: 0, power good: yes
With low voltage I can move the motors , the voltage do not change in the power supply, I use a 30A/24Volts Power Supply for Duet2Wifi (motors and hot end), for thehot bed I use a separate Power Supply 12Volts/50A, I use separate Mosfets for hot bed and hot end.
I don't know what's going on. Sometimes the voltage is high and the motors do not start, sometimes the voltage is low and I can print to a certain point until the machine suddenly stops.
I tested the reference voltage on inductor L5 and Capacitor C64, the voltage is 3,29 Volts .
I checked the temperarture in Wifi Board and SD Card whith my PIR thermomether 33,1 °C and 33,1° C.

Is it possible that the processor is defective Or could the inductor and capacitor be in trouble?
Could it be problems in the inductor?
If I change the inductor L5 and Capacitor C64, will it solve?

dc42

I am confused. First you reported that the voltage reported by the Duet was 34.2V. Now you are saying it is 14V. Whar did you do to provoke the change?

hackinistrator

if i'm not wrong , Vref is also powering thermistors .
try to disconnect all your thermistors and see if the voltage reading is right .

Milke

@dc42 I am also confused, because sometimes when I turn on the machine, the voltage shown on the DWC and detected by the board is around 30 volts and sometimes around 14 volts, but the power supply is stable at 24 volts all the time.
I also checked the 3,3 Volts line on Board, it is ok, I also Checked the 5 volts line and the results are ok.
ADVREF or VDDOUT problems? Or VDDIN or VDDCORE?

Milke

@hackinistrator Are you referring to thermistors 0 to thermistor 7?

hackinistrator

@Milke i see only 0 to 2 connected to Vref . maybe if one of them is shorted to +24V it effects the reference .

Milke

@hackinistrator said in Attempt to move motors when VIN is not in range:

@Milke i see only 0 to 2 connected to Vref . maybe if one of them is shorted to +24V it effects the reference .

Could you help me identify it on the board? Their number and position?

Milke

@hackinistrator Do you refered to bed thermistor and hot end thermistor? I disconnected both, the same problem, powe suplly 24 volts, DWC show me 17 volts

hackinistrator

@Milke it might be bad adc i guess .
if Vref is bad , then i guess you should also see your hotend / bed temps fluctuate , this is not the case , right?

maybe also try connecting the board to your second 12v supply and see if the readings are also off .

Milke

@hackinistrator said in Attempt to move motors when VIN is not in range:

maybe also try connecting the board to your second 12v supply and see if the readings are also off .

The hotend / bed temps are correct, there is no variation, they remain constant as a function of time.

I changed my 24 volts power supply, and the 12 volts power supply too, the problem persists. Nothing changed.
24,3 Volts on the new 24 volts power supply and around 17 volts on DWC.

Milke

HI people. The same problem, today I can not start the machine because the Vin is 9,1 volts, yesterday I printed whith 18 volts...

Anyone can help me?

Phaedrux

Checking to see if there is any means of repair short of replacing the MCU.

When and where was the Duet purchased?

Milke

@Phaedrux said in Attempt to move motors when VIN is not in range:

Checking to see if there is any means of repair short of replacing the MCU.
When and where was the Duet purchased?

Sorry, I don't understand, do you say to replace the MCU or try to repair it without replacing the MCU?

I bought it from a friend in Brazil who referred me to the duet.
Last week I bought a Duet2Wifi clone from Makerbase in China, as I live in Brazil, the pound is very expensive for us, the cost of importing a Duet2 from England is around 364.30 pounds.
Today when I turn on the machine, the voltage shown on the DWC and detected by the board is around 2,60 volts. Yestarday was around 14 volts, but the power supply is stable at 24 volts all the time.
I also checked the 3,3 Volts line on Board, it is ok, I also Checked the 5 volts line and the results are ok.
ADVREF or VDDOUT problems? Or VDDIN or VDDCORE?
It is possible to repair Verfe components or it is necessary change the MCu....
I attached the simulation to buy a new Duet2wifi to Brazil.

Phaedrux

Unfortunately the quality of the clones is hard to predict.

What kind of access to hot air rework and oscilloscope do you have? Whether the effort is worth it, or just replacing the board entirely may be more effective.

alankilian

@Phaedrux Is Vin monitored through one of the POWER_FAIL_DETx inputs?

If so, he could measure the voltage at those components and see if it's strange. It's possible one of the two resistors in the divider are poorly soldered or cracked.

Milke

@Phaedrux I have an oscilloscope but I do not have acces to hot air station to replace the MCU, some components like to resistors or caps no problem to replace.

Milke

@alankilian said in Attempt to move motors when VIN is not in range:

@Phaedrux Is Vin monitored through one of the POWER_FAIL_DETx inputs?
If so, he could measure the voltage at those components and see if it's strange. It's possible one of the two resistors in the divider are poorly soldered or cracked.

@alankilian , do you refer to components like resistors and capacitors connected to PWR_FAIL_DET2 R80 - 47K, R81 - 4K7 AND C79 - 10nF and PWR_FAIL_DET R15 - 47K, R16 - 4K7 AND C80 10nF?

Attached a figure showing these components in the electronic circuit.![0_1616540703227_referential_problem.jpg](Uploading 100%) ![0_1616540753983_referential_problem.jpg](Uploading 100%)

alankilian

That's exactly what I'm talking about.

Those two resistors form a resistor-divider that produces a signal that is 9.1% of the input signal. (0.091 multiply by)

So a 12-volt input will produce 1.09 volts on the output signal.

HERE'S a page that lets you simulate a voltage divider.

Milke

@alankilian, @Phaedrux and @dc42. I solved the problem, thanks for yor tips and support.

I discovered the electronic component that was damaged, it was a 47K resistor (R80) of the voltage divider (PWR_FAIL_DET2).

I replaced the resistor with another resistor and my machine returned to normal!