PanelDue Flashing on and off



  • I have a 7" PanelDue and the display has not decided to turn itself off and on at approximately 1 - 2 Hz. Otherwise, it seems to be operating fine and control from the panel continues to work.

    What are the likelihoods that this is a defective panel vs. a defective PanelDue controller? (If I had to guess, I'd guess panel)

    Thanks!



  • A little more investigation…

    I unplugged the SD card cable and the blinking slowed down to half speed and the panel dimmed to 50% brightness. Plugged the SD card cable back in and the blinking stopped and brightness returned.

    Does that make this a possible issue with power from the Duet Wifi?


  • administrators

    Are you running the Duet WiFi with USB power only? If so, that's normal. It's because the Duet + 7" LCD takes more than the 500mA power output of a standard USB port. Either power the Duet with 12V or 24V Vin power, or provide additional power through the USB connector on PanelDue.



  • @dc42,

    Nope, I'm running the DuetWifi on 24V power from a MeanWell power supply and has been working fine this way for months. Unplugging and replugging the SD card cable fixed it.

    It's probably a good idea to go ahead and run separate power to the panel since I seem to be on the edge of being able to power the panel from the Duet.



  • Leon -
    i, too, run 24v off of Meanwell power supply – also have had it setup this way for multiple months. the only thing that changed relatively recently (about 3 or 4 weeks by now, I'm guessing) is that I had to swap out the Duet Wifi board due to user error (blew the quick reacting fuse that governs the temperature system within the board by inadvertently shorting it by a connector fraying and contacting neighboring pin on effector -- bad luck). That being said, thankfully mine has not gotten as bad as to where I'd asign it a hertz value for the consistency of the flashing of on/off of the PanelDue 7" (v1.1), though just yesterday i thought maybe my eyes were playing a trick on me but i could've sworn I saw the panel flicker a few times over the course of an hour or so. That being said, I'm gonna keep an eye on this threwad for possible suggestions by the wizardsas to how to handle and/or address such issues if they crop up.

    Gooid luck with yours and wish you well.

    Jonathan



  • This started happening with my 7" Paneldue (v1.1) yesterday during a print.
    On-Off with about 2 times per second. All information is shown and the rest works, incl touch, as it should.

    Connecting with USB (only, not tested with both connected) and the flickering it gone, so the screen works.
    I updated to the latest Paneldue fw but no change. Duet running latest fw too.

    Checked the voltage on the cable and it read 4.95-4.99v so that seems fine, but I will check this again tonight.

    any other ideas?



  • Checked voltage "output" from the Paneldue and it goes up and down from 3v to 4.5v and a noticeable buzzing sound is made
    every cycle, probably due to the LCD lighting up.

    Is the PanelDue dead?


  • administrators

    It's unlikely that the PanelDue controller board is dead. Check the 5V supply on the input to the PanelDue controller board at the 4-pin connector. If that is also going up and down, check the 5V supply on the Duet's PanelDue connector too.



  • Tested the following now.

    Cable from Duet: 4.87v steady
    Cable from Duet only Paneldue:

    • Pin directly: 4.87v
    • 5v pin on the pins going to the LCD (LCD not connected): 4.5v

    Same 5v pin above when connected to LCD: jumping between ca 3v and 4.5v (flickering)

    LCD when power only from USB3.0: ca 4.3v on above pin (not flickering)
    LCD when power from both duet cable and USB: 4.3 (not flickering)

    So something has all of the sudden started screwing with the voltage when it comes from the duet cable only.
    My electronics skills are not good enough to say where though.. I see no damaged parts on the LCD.

    ideas? besides scrap the LCD..



  • It sounds like the PanelDue isn't supplying a steady 5v to the LCD, possibly a damaged trace or bad connection.


  • administrators

    @Jimborr:

    Tested the following now.

    Cable from Duet: 4.87v steady
    Cable from Duet only Paneldue:

    • Pin directly: 4.87v

    Please clarify: were those voltages measured with the LCD connected and flashing (no USB power supplied), or not? And were BOTH of them steady?



  • @dc42:

    @Jimborr:

    Tested the following now.

    Cable from Duet: 4.87v steady
    Cable from Duet only Paneldue:

    • Pin directly: 4.87v

    Please clarify: were those voltages measured with the LCD connected and flashing (no USB power supplied), or not? And were BOTH of them steady?

    Both above, steady, voltages were without LCD connected.

    I just tried checking the pins on the connector on the paneldue (where the cable is directly connected) when connected to the LCD (no USB) and it fluctuates, however it's a more
    slow up and down between ca 3.5V and 4.7v. I recorded this and will link it as soon as I'm able to.



  • Please don't mind my shaky morning hands. 😉

    This is when everything is connected, except USB.

    https://youtu.be/_B7j–lrO-4


  • administrators

    If the voltage on the 4-pin PanelDue connector is fluctuating, that points to a problem either on the Duet or more likely in the cable connecting the PanelDue to the Duet. Probably a bad crimp connection.



  • @dc42:

    If the voltage on the 4-pin PanelDue connector is fluctuating, that points to a problem either on the Duet or more likely in the cable connecting the PanelDue to the Duet. Probably a bad crimp connection.

    I will take a look at the duet side tonight if I get the time.
    But it only happens when the PanelDue is connected to the LCD. If I disconnect the PanelDue from the LCD is stops and just gives a nice stable 4.8-ish voltage.

    Thinking that perhaps the LCD is bad and messing with the voltage from its side.


  • administrators

    The backlight inverter is responsible for most of the current draw, and it will only start when the voltage is high enough. That explains why the voltage is stable when the TFT panel is not connected.



  • Starting to suspect the inverter then. Read that there would be a buzzing sound when it's broken, which sometimes comes from the LCD panel when this is happening.

    New 5" needs to be ordered then..

    Thanks for the help David, always a pleasure to get your insight!


  • administrators

    I still suspect the cable.



  • @dc42:

    I still suspect the cable.

    I'll check it when I'm rebuilding/re-cabling when my PCB Effector kit arrives 🙂
    Don't have the cash for a new screen atm anyways 😄


 

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