I got a RAMPS board that was poorly soldered, with sputtering, joints with gaps, and generally dull looking solder. I used it anyway and I have not yet gotten it to work properly. I am able to get the LCD working and I have been able to control the motors sporadically, but not the heaters.
Mostly, I have tried reflowing the solder. Eventually I overdid this, and shorted out 5V and GND, causing the board to fail completely, but I've fixed that now.
I've also replaced the 10 nF caps for the thermistors with polymer film caps, and I've twice replaced diode D2 (the one by the polyfuses). It seems to have failed, because the first diode and the one I replaced it with eventually gave no resistance in either direction and did not register a voltage drop when I diode tested it with a meter.
I suspect there is a short, but I can't find where it might be. As a rather extreme measure, I completely removed the servo block and the two AUX blocks I wouldn't need, leaving only the LCD connectors. The idea was that I would remove these unnecessary components in case the point of failure was somewhere in that part of the circuit.
There was definitely a short at the VCC pin of the 3-pin connector near the reset button. It smoked and glowed after a few seconds.
For external power, I only have a 5 V 2 A and a 12 V 0.7 A power block. The 12 V one seems to help. When I can get the board powered up, the LCD flickers, or at least fluctuates. When I connect anything to D8 D9 D10, the FETs heat up.
My Arduino Mega clone seems fine. I have tried testing the analog readouts and they work. Sometimes the board does heat up in the space between the barrel plug adapter and the USB port -- AFAIK that is a voltage regulator and a thermal fuse.
Where I'm at now is that the LCD flickers a lot. I suspect perhaps I shouldn't try powering the Arduino from the RAMPS board at all -- does that mean removing the Vin connection?
Any ideas on what I can do? At this point I'm very frustrated because buying a replacement board isn't a possibility for the next few days. I've definitely learned a lot about the RAMPS board and improved my soldering significantly. I really would like to fix the board.
Mostly, I have tried reflowing the solder. Eventually I overdid this, and shorted out 5V and GND, causing the board to fail completely, but I've fixed that now.
I've also replaced the 10 nF caps for the thermistors with polymer film caps, and I've twice replaced diode D2 (the one by the polyfuses). It seems to have failed, because the first diode and the one I replaced it with eventually gave no resistance in either direction and did not register a voltage drop when I diode tested it with a meter.
I suspect there is a short, but I can't find where it might be. As a rather extreme measure, I completely removed the servo block and the two AUX blocks I wouldn't need, leaving only the LCD connectors. The idea was that I would remove these unnecessary components in case the point of failure was somewhere in that part of the circuit.
There was definitely a short at the VCC pin of the 3-pin connector near the reset button. It smoked and glowed after a few seconds.
For external power, I only have a 5 V 2 A and a 12 V 0.7 A power block. The 12 V one seems to help. When I can get the board powered up, the LCD flickers, or at least fluctuates. When I connect anything to D8 D9 D10, the FETs heat up.
My Arduino Mega clone seems fine. I have tried testing the analog readouts and they work. Sometimes the board does heat up in the space between the barrel plug adapter and the USB port -- AFAIK that is a voltage regulator and a thermal fuse.
Where I'm at now is that the LCD flickers a lot. I suspect perhaps I shouldn't try powering the Arduino from the RAMPS board at all -- does that mean removing the Vin connection?
Any ideas on what I can do? At this point I'm very frustrated because buying a replacement board isn't a possibility for the next few days. I've definitely learned a lot about the RAMPS board and improved my soldering significantly. I really would like to fix the board.