A while ago I accidentally shorted the fan pins (or something around the fan connector) when I slipped with the multimeter probes resulting in the pcb trace connecting Fan+ to +Vin was burned loose from the pcb and the fan was no longer working. I fixed this by soldering a wire between Fan+ and +Vin.
Some week later when I connected the printer to my laptop I suddenly lost the connection to the printer (Windows played the “disconnect USB device sound” and showed some warning but I didn’t have time to read it before it was gone). First thing I tried was to disconnect the USB-cable and connect it again and that is when I felt that the USB-cable was really hot. Since then the USB-connection has been dead, I have tried a different USB-cable and I know the USB-port on my laptop still works.
When I think back if believe the pcb trace that was burned loose was still connected on the +Vin side and the trace is routed under the USB-connector on the board. Could it be that the shield of the USB-connector was connected to +Vin and that caused the hot cable and destroying the USB-connection? I have removed all parts of the trace I can access (still some left under the USB-connector I am sure but it is not connected to anything anymore). Could the FT232R be destroyed? The RX and TX LEDs are constantly lit when the board is connected to the laptop, I don’t think that was the case before.
I replaced the FT232R IC with a new one and the good news is that I can now connect the printer to my laptop and control it using Repetier Host. The bad news is that I can still not flash new firmware (timeout communicating with programmer) and the RX and TX-LEDs are always off.
When I replaced the FT232R IC I accidentally ripped the solder pads off the PCB for pins (DSR#, DCD#, CTS#, CBUS4, CBUS2, CBUS3) luckily it appears they are not connected to anything. I have checked the solder joints and they look ok, I also checked that the CBUS0 pin is connected to LD6, CBUS1 to LD5 and DTR to MCU Reset all ok.
I assume DTR should be pulled low (reset MCU) when flashing new firmware, however DTR is always high. It is possible to set DTR low from the laptop using an application I wrote and I see that the reset pin on the MCU goes low.
Can anyone try to explain why connecting and controlling the printer from my laptop works but flashing firmware and the RX and TX-LEDs don’t? It is possible that something other than the FT232R IC was damaged, in that case maybe someone who is better at electronics than me can give me a clue based on the description above what components could be broken.
Thanks for replying. Yes I used a jumper on the JPROG and I am using Arduino 1.0.6.
I am now able to upload new firmware, the DTR pin is actually pulled low. Not sure exactly what I did to make it work but I desoldered the resistor (R9) and Schottky diode (D2) to test them while not connected to the board in case they got damaged when I replaced the F232R IC, they seemed ok. I never soldered the Schottky diode back on the board before trying to upload new firmware and it worked. Maybe it has nothing to do with it but for now I have left it off, what is the purpose of the Schottky diode in this case? The TX- and RX-LEDs still don’t work though, I have seen the TX-LED flash occasionally but most of the time the CBUS0 and CBUS1 pins are ~3.8V even during communication, I believe they should go low in order to turn the LEDs on.
I can live without the LEDs working but the strangest thing has happened, the stand alone controller no longer work. It worked before I replaced the F232L and I am using Firmware v.2.2. I can still access the SD-card (I can list all gcode-files using command M20) and the reset button works. But the display only displays black rectangles on row 1 and row 3, row 2 and 4 show nothing. I suspect the display doesn’t get initialized correctly even though I know the initialization code is executed.I have checked all pins involved in controlling the display all the way from the MCU-pins to the HD44780-pins (including GND and +5V) and all looks ok. I don’t see how replacing the F232L could affect the stand alone controller, it was working when the USB-connection was completely broken.
I know why the stand alone controller display is no longer working, I checked the communication with a logic analyzer and MCU pin PC4 (LCD_PINS_D6) seems dead. Don’t ask how I have managed to damage it but it is always high, trying to toggle it from the software does nothing. I temporarily remapped LCD_PINS_D6 to PH1 and now the stand alone controller display works. As a permanent fix I hope I can just cut the trace between MCU pin PC4 and the stand alone header pin and connect that pin to a working unused MCU pin like PG0 (closest to the stand alone header).