I am hoping there is a person that knows the deep inner workings of a Rambo 1.4 that can offer some insight here. I am rebuilding and I think I may have damaged my Rambo 1.4 in the process. Blew out the serial comms anyway. When I fired back up, I am just getting a blank LCD (backlight is on, and fuses are all good). I am also unable to connect via PlatformIO, but I am not sure if it is because of Windows11 (new machine) or the board itself. The COM port does not show it as a RAMBO, just a USB device, but it does show up.
In the rebuild I did not disconnect the working LCD from before, so the cables were not switched or anything. As a debug, I also tried a second display, and a second set of cables with all same results. The only other wires that were redone were the steppers and the limit switches AND an extra serial connection that I accidentally pulled off that I have going to a pendant (home built to use a joystick and an arduino for some custom buttons). That connection is on the Rambo X39 header. I believe when I first pugged it back in, I was off by two pins low on the header. So the mis-connection would have in theory crossed VCC and GND thru the pendant on the Serial expansion (X39) and the Analog expansion (X40) since the X40 also has that wired to the pendant. Does anyone know if what I am seeing is indicating a blow out and is it recoverable?
Below is schematic from my pendant wiring and a link to the Rambo schematic.
I don’t know the deep inner workings, but I have Rambos that are used on my TAZ 5 3D printer.
The good news is that Rambo boards are really robust. Not unbrekable, but better than most.
We need to seperate your problems into two.
The LCD is one set of problems, the connectivity to Windows 11 is a different problem.
The Windows connectivity is most likely a driver issue where you don’t have the correct USB driver on the windows box.
For the LCD, the first step would be to test with ONLY power to the Rambo and the LCD connected. No other wiring at all should be connected to the board.
Can you provide a high resolution picture of your Rambo in the machine, and a picture of the LCD?
When you power up the rambo, does the LCD show it has power but the screen is blank, or does it remain completely dead? (Most displays will at least have a backlight or LED on them which turns on if the display has power, regardless of whether or not there is content on the display)
Note that you cannot use the USB connection and RX0/TX0 at the same time. If you haven’t already, disconnect your pendant and try USB communication again.
You could modify the firmware to add a second serial port. Then you can use TX1/RX1 on the Rambo board for your pendent, and the USB connection also work at the same time. Adding a second serial port is done in this section in configuration.h:
/**
* Select a secondary serial port on the board to use for communication with the host.
* Currently Ethernet (-2) is only supported on Teensy 4.1 boards.
* :[-2, -1, 0, 1, 2, 3, 4, 5, 6, 7]
*/
//#define SERIAL_PORT_2 -1
//#define BAUDRATE_2 250000 // :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000] Enable to override BAUDRATE
As for your display issues, it is possible that you blew a voltage regulator when you crossed VCC with ground. Check that you have 5V somewhere on the board. You can check using the pins in the grey and red rectangles here:
If you need to check the display specifically, according to the schematic, VCC and Ground are pins 1 and 2 on Extension 1:
I added the RAMBO Driver, and now the USB shows it to be a Rambo. Progress there. I had skimmed back thru the build documentation (been years) and didn’t see a driver reference, so forgot I would need it.
Double checked my connection to pictures taken just prior to disassembly as well as ones from March 2020 and all seems to be in order (same connections) but not working.
@robertbu I do have the extra serial port defined as shown and has been working great. I built the pendant a long time ago and it was all good until I restarted this time. You may have been the one to point the need for the second serial port at the time (back in 2020). Can’t recall .
I checked for the 5V in a few places as well as where you indicated and is good there. At the moment I am unable to connect to the board to flash. I get timeout errors from PlatformIO, so I am suspecting the logic is somehow fried.
The reason I mentioned TX1/RX1 is because your diagram above list TX0/RX0. When I built my pendant years ago, I made the mistake of using TX0/RX0 and was initially flummoxed when my USB connection would not work.
It is not looking good for your board, but before giving up, I would unplug the pendant and the display and try connecting through USB on both your Windows 11 machine and perhaps on a friend’s Windows 10 machine. If you messed with the endstops, I’d unplug them as well. I’ve seen the behavior you describe in boards that have an ongoing short in the endstops.
If you haven’t already, you might try connecting to your Rambo board using Repetier-Host. You can select the COM port to use, so you will have a better idea if the board is communicating to the Rambo board.
As mentioned by MakerJim above, Rambo boards are hardy. I’ve seen posts on the forum where they’ve survived stupid stuff that would fry lesser boards.
Long story short - turns out the reset switch on the Rambo was stuck in. Not sure how it would get that way. Never touch it, and it is buried in the enclosure! When I wiggled it to un-stuck it and turned it back on, everything was normal again. Phew!!!
That’s a new one. Very glad you got it fixed. After watching posts about the Rambo boards for years, I never count a board out until everything has been tried. Almost always they come back to life when the issue is addressed.
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