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Discussion in 'Mods and Upgrades' started by Lance Weston, Mar 27, 2019.
i think that is the spare port for the second hotend extruder
Makes sense now that you have pointed out the situation. Second hotend thermistor to pin 13 and then on the main board end, to the "unused" point (indicated at the top of the diagram).
The two thermistors on the connector on the lower right are for the two hotends. At the top of the schematic you can see the thermistor for the bed. If you use the existing downtown board which has the thermistor grounded you will not get good temp regulation, but it will work. Partsbuilt.com supplies a modified downtown board having a jumper to isolate the ground on the hotend thermistor one, bringing it to the hot on hotend two. The result is that you use the two thermistor lines as both ends of thermistor one. This will give you much better temp regulation. The ramps board prefers an isolated thermistor. I have used the Partsbuilt board and it works great. I have also removed the hotend one connector from the downtown board, used a diamond bit in a dremmel to isolate the gnd, then reinstalled the cconnector and jumped the now isolated ground to the hot on thermistor two. This also works. I bought the Partsbuilt boards because it is easier and looks better.
you can still make things work without isolating the gnd end of thermistor one. Just be careful, in that the the connector on the ramps would now be polarized. Gnd to Gnd and hot to hot. Reverse this and the you would be grounding the hot and get a crazy reading on the LCD
i am having trouble finding a 15 amp fuse holder that would fit where the 5 amp ptc fuse was. any suggestions as to where i can pick one up?
these are what I purchased. All required some dremel work and then fit
I can not figure out which diagram you are referring to. The thermistor for the print bed runs directly to the Ramps board and the thermistor for the head runs through the cable. The modified downtown board has a jumper that either GND's the thermistor 1 (-) or routes it to thermistor 2 (+). For the Ramps I use the the two (+)'s to get an isolated thermistor.
Lance, My R2 is still getting bad ADC reading by the firmware. I installed the modified downtown board and set the jumper between center pin and gnd. TEMP_0_PIN is configured to be 13. I've run all of the extruder connections from the ribbon to a breakout board (bb). I've connected bb pins 13 and 15 to the ramps 1.4 T0 connectors. I get about 99k ohms across the extruder thermistor at room temperature (directly at the thermistor and also across pins 13-15.
The firmware reports for the header thermistor, ADC=5007 (333 * OVERSAMPLENR) with a computed temp of 142 C. At room temp I think it should report ADC=15632 (977 * OVERSAMPLENR) and 25 C.
I’m not sure how the new ground connection should be handled with the connection to the ramps board. I’m assuming that the bad ADC is related to a floating resistance rather that some setting in the Arduino code. Any ideas to suggest. Thanks J
sounds like the hardware is correct. Just as a sanity check ohm out 13 and 15 to GND, make sure there is no short to GND. If there is no short and you have it connected to T0 on the ramps it is most likely firmware. I attached working hex code. Change the extension from PDF to HEX. Load onto a USB fat32 formatted, using the LCD got to Files->USB and run the file. After it has loaded use Octoprint terminal and run M502 (load eeprom) then run M500 (store eeprom) now go to system on the LCD and do a restart.
I just used this code on a new Ramps install. It has my 3950 table used on both hotend and bed.
Good news: The new Partsbuilt.com boards have arrived from China and are on their way to me. I will have to stuff and test, but I would expect results within a few weeks.
The right side screw that holds the shroud on may be shorting the modified board jumper to GND, try removing it for a test.
change the extension from PDF to XLS and look at this spreadsheet. You can see that the ADC is a 1024 count. The table should give you the count every 5 degrees.
I'm showing pin 13 on breakout board as shorted to gnd and pin 15 shows 92kohm. I'm also seeing a problem with my connector to T0. I'm going to fix that. In the meantime, My rPi is running but the LCD is flacky and not responding to touch. I can control from octoprint but see below. Currently i'm using a usb connection between the mega2560 and my pc usb. I've been using prontface and pronsole to connect to the 2560 and run debug code from my local arduino build. I'm unclear on what your suggestion about the hex code, fat32, files->usb. what are these steps trying to accomplish? Is it supposed to place the hex code on the rPi SD card? (I do have a backup but ???.) I put the hex code onto a large finger drive and the R2 usb does read it. Can i do these steps via my prontoface link? Thanks for your help. J
The hex code is to load on the Marlin board, but you have a hardware problem so lets solve that first. The right side screw that mounts the shroud is directly under the downtown board jumper on the early boards. Remove the screw and see if the GND disappears. You can always print out a short plastic spacer to drop the screw down if it is the problem. If that is not it, you can align the GND side of the thermistor with the GND side of the Ramps input. That should get you operational.
ok, I'll check the downtown board and get that clear. after that I should be able to upload the hex file to the marlin 2560 board and I'll put it into the eeprom. Is this hex file a good version of the arduino code to that should work with my version of the R2/ramps/2560?
Yup, all of this is standard if you have the D8,D9,D10 where I had it. My version of hex drops the bed enough that you can use the flexplate system. What are you using for the 12v and 5v supplies?
I did post what Arduino boards are compatible. The CH431 cheapies do not work. If you are communicating with the LCD then you are good to go.