please help

[jimc]

Hmm yes but not if it needs an M999 reset. Worse case just reflash the firmware. On an unknown machine its probably the best thing anyway. Who know what the previous owner messed with

[insta]

shouldn't i still be able to jog the axis's though?

The printer won't do anything if it can't read the thermistor. Hopefully you saved some money with a used M2, because I see some upgrades in your future:

* V3B hotend (I'd get this anyway -- your thermistor or its wiring is suspect)
* 24v upgrade

[greg c]

Yes I got a good deal awith the awareness it was an older model I may have to upgrade anyway so thats fine. So to be clear, the v3b hot end is a worthwhile upgrade in addition to hbp and 24v upgrades?

[Dale Reed]

greg c,

If the thermistor connection is open, it will read 0 for the temperature. You should still be able to jog X, Y and Z. You won't be able to jog the extruder. You will not be able to heat the hot end, either. (The firmware does this because there's no temperature feedback, so it won't know when to STOP heating!)

Does the heated bed temperature read properly? (As stated, room temperature in Celsius...) If so, can you enter a temperature for the bed and heat it -- to, say, 40 degrees C (just to not push it)?

There are a few ways that the thermistor circuit could be open:

1. Bad thermistor
2. Broken wire on thermistor
3. Wire from thermistor is not properly clamped into the connector pin, or pin not seated properly in connector shell, or pin corroded, etc.
4. The connector for the thermistor is not correctly plugged into the connector on the wiring harness.
5. Wiring harness wire not properly clamped into a connector pin, or pin not seated properly in connector shell, etc.
6. The connector at the circuit-board end of the wiring harness is not plugged fully into the right connector on circuit board.

( See page 3 of http://cdn.shopify.com/s/files/1/0030/7 ... 13.pdf?917 -- the thermistor circuit for the hot end plugs into "T0", on the right side of the picture. Note that the left side of the picture is the FRONT of the machine, and the right side of the picture is the BACK of the machine. )

7. The input circuit on the circuit board for the thermistor input has been destroyed.

Note that the thermistor is not a "polarized" device --- it has no plus or minus side --- so it doesn't matter "which way" it is connected --- as long as the circuit is made.

Are you handy with a multimeter? If you unplug the thermistor from the wiring harness, near the hot end, you should be able to read its resistance. I believe it will be somewhere near 100k ohms at room temperature, something like that. And the resistance should go DOWN some as it gets warmer.

HERE'S A TEST YOU CAN DO if you open up the electronics enclosure: The hot end thermistor plugs into T0, and the heated bed thermistor plugs into T2. (Refer to page 3 of the document above.) TEMPORARILY swap these two connections. If your software now shows a temperature for the hot end and no temperature for the bed, the problem is either an open connection in the wiring harness or the thermistor is bad. If the software still shows zero for the hot end and shows room temperature for the bed, then T0 input on the Rambo board is bad.

Condensing all of the above: Either the circuit for the thermistor is OPEN, somewhere, or the thermistor input on the Rambo board is bad.

Hope this helps!
Dale

[jimc]

well the v3 and v3b are essentially the same hot end just the heating system is different. it uses a block and cartridge instead of a hand wound core. what you will want to do is get your printer up and running with what you have now. get familiar with it, work out any bugs then upgrade to the v4 when that is out. not sure if the single v4 still needs the 24v setup or not. i would assume not. the 24v setup is not necessary but probably nice. i have the 2 bricks and the advantages compared to the upgrade expense isn't really worth it to me. it shaves about 4-5 min of bed heatup time off is about it. the current running through the rambo board connector would be less as well which is a known weakness of the board. if you keep the contact clean and tight then you should be ok. other than that there is nothing wrong with the 2 brick 19v setup.

[insta]

Go ahead and contradict everything I said guys, it's cool

[jimc]