Welcome to the SeeMeCNC Community

My RAMBo no longer shows up as a USB device. Is there anything to try short of replacing the RAMBo board?

Here's how it happened.

I had finished up with the dial indicator, and reinstalled the hot end. I had to do this three times because of issues with the silicon tape I use to insulate it. On the third reinstallation, the RAMBo went wonky. I turned it on and the LCDs never initialized. I poked and prodded things, and a few minutes later the LCD display came back. But (a) the LCD says the thermistors are bad - prints "def" for the current temperature, (b) Repetier Host-Mac can not open the USB port.

What have I tried?

• Restarted the Mac.
• Checked both thermistors' resistance at the RAMBo connectors. Both read ~100K.
• Looked for the USB port in the Arduino IDE. It is not there.
• Verified that an Arduino Uno works on that USB port and cable. (Flashed firmware and did serial comms.)
• Tried a different USB cable in the same USB port. Repetier Host-Mac nor Arduino IDE can open the port.
• Verified that the Arduino Uno works on the new cable.
• Unplugged the hot end (thermistor and resistors).

I have *not* mucked with the software setup. It has been working for a month, and it stopped working on a routine Repetier disconnect/reconnect sequence. And the driver level, at least, it still works fine with other Arduinos. And I've never touched the baud rate. It is still 250000, confirmed in the LCD menus and in Repetier Host settings.

What else can I check before I replace the RAMBo?

Configuration info:

Rostock MAX purchased 5/19.
RAMBo 1.1 board.
RepetierMAX firmware from github.com/SeeMeCNC/RepetierMAX.
Repetier-Host Mac Version 0.56 (5.3).
Arduino 1.0.5.
Mac OS X 10.8.4 Mountain Lion.

If you can , try it on a different computer

tom10122 wrote:If you can , try it on a different computer

Good idea. I'll scare up another one with Arduino IDE and drivers. (I already ordered a new RAMBo, but I want to understand what happened to this one.)

If I read this right...

You have two problems. Not one.
USB:
If you see it in Arduino, it should flow through to Repetier.......meaning that Repetier is a problem somehow.

Don't trust that you get current all the way through from the board to the hot end. Try seeing if you have a short between either end of the thermistor to the hot end or the resistor/cartridge... "def" means confusion or no throughput. Either way a short would do that.

Lastly, just for a prank, take a good look at your power leads....

Lately, I quite trying to check this and that. I start all the way from the power and go down to the component. So much futzing with pieces / parts has caused me to do this.

I'll be very thankful for more modular setup on the Rambo, I can't tell you...

JohnStack wrote:If I read this right...

You have two problems. Not one.
USB:
If you see it in Arduino, it should flow through to Repetier.......meaning that Repetier is a problem somehow.

Don't trust that you get current all the way through from the board to the hot end. Try seeing if you have a short between either end of the thermistor to the hot end or the resistor/cartridge... "def" means confusion or no throughput. Either way a short would do that.

Lastly, just for a prank, take a good look at your power leads....

Lately, I quite trying to check this and that. I start all the way from the power and go down to the component. So much futzing with pieces / parts has caused me to do this.

I'll be very thankful for more modular setup on the Rambo, I can't tell you...

You were correct. The hot side of my resistors is shorted to the thermistor. I will have to repair that. I wonder whether introducing +12V to the thermistor input could have fried the RAMBo's USB interface.

Not likely. I think there are a couple of diodes in there that would prevent it.

The thermistor port is most likely fried and you will have to check. I agree with John about the Rambo being okay except the thermistor port.
Hey, it's possible you got lucky and everything will be okay once you get the wiring repaired.

I want to close up this old thread. I did replace my RAMBo. I did not recover the USB port on the first RAMBo. More details are in my build log thread: Death of a RAMBO.