And Back to getting my Two Trees Sapphire Plus working

[rongee]

In other threads, I've described my adventures getting this printer working. As of February, Two Trees had shipped me a new thermistor to replace the one in the unit that they determined was defective. And so, we continue.I've managed to take apart most of the extruder in order to get at the thermistor. I'm including some pictures. I've removed a larger cylinder that, due to the heavy wires, I'm assuming is some sort of heating element, that was locked in with a set screw. The thermistor is a much thinner cylinder next to it. I can't figure out how to remove it as it is jammed into its hole pretty tight. No set screw. I've tried pushing it through from the opposite end, but it won't move, and before I stick the thing in a vice and start putting some heavy duty pressure on it, I thought I'd check here first. Should this thing be the hard to get out? As always, thanks for any guidance. Ron

[Gambo]

If your hot end is the same as the Sapphire pro the locking screw for the thermistor is hiding up a hole accessible from next to the heater locking screw. It is an M3 like the heater locking screw. You can see it in your photo of the bottom of the heat block. incidentally be carefully tightening the heater screw the thread is very short in the heater block so strips easily, then the only solution is to drill right through the block, tread the new hole and lock it from above.Gambo

[Gambo]

Incidentally the thermistor is available on Amazon HT-NTC 100K TYPE 3950 5 off £12

[curious aardvark]

prettu sure they both use the same hotend.
So yes, there will be a very small grub screw in there somewhere :-)

[Gambo]

yup the one I loose every time M3 by about 5mm

[rongee]

Thanks a lot, guys. I'll take another look. I saw the hole you mention, but let me take another really close look at it and get back to you.

Again, really appreciate the help. Gambo, yes, I'm trying to be really careful not to lose the screws, including the set screw for the heating cartridge, that I've pulled out so far. I was working on the mount for my telescope awhile back, ended up with separate little containers for all the screws, and still managed to lose a couple of the little ones. I'm pretty convinced that those little M3 screws evaporate when exposed to air for too long. :-) "CA", you've come to my rescue again. Much appreciated.

[rongee]

Well, Hah! I went searching down in that 2nd hole again, the one near the thermistor. Like I thought, the upper half of the hold isn't threaded, BUT, based on your advice, I went fishing down there is a little Allen wrench, and wouldn't you know it, it caught on something. So, sure enough, there's a little set screw down in the there, so the bottom half of the hole is threaded. Once I loosened that, the thermistor was still jammed in there pretty tight, but I was able to finally get it out. Far as I can tell, the "wire end" of the thermistor is slightly larger than the rest, and that's where it was hanging up. The replacement piece has that "wire end" flattened, so you can't even insert that, but it goes in far enough to get caught by the set screw. So far, so good.

Before I put everything back together, I'm just going to assemble it far enough so that I can reconnect the wiring to the motherboard and see if that fixes the error message I was getting.

I'm going to assume that I'll be back after I run that test, so see you then.

thanks again.

Ron

[rongee]

Okay, I'm getting ready to run some initial tests on the replaced thermistor. I'm wondering if there is a way to display or otherwise print out the firmware settings? Also, there are 2 sockets on the motherboard (An MKS Robin Nano v1.2) labeled "12V/24V Constant Output". Wondering if it's 12V or 24v. I'm not at the printer right now, but off the top of my head, the only way I can think of to determine what voltage the printer is using is to stick a voltmeter on the leads coming from the power supply to the mboard at the contacts labeled "Power Interface". Or is the power actually determined somewhere else on the board? The original Robin Nano manual mentions something about a "dedicated power chip" (I found a v1 manual on Github, but still looking around for a v1.2; probably someplace obvious that I missed). I'm attaching a picture of the v1.2 mboard from the instructions that I received, just for reference. Thanks again.Ron

[Gambo]

Hi Rongee
The power supply in the sapphire is a 24volt 360 watt unit -at least according to the machine spec and my unit.

to see the internal firmware settings you need to use something like Prontiface and connect via the usb connector on the sapphy . Prontiface is available as a free down load i don't remember where I got it from but I will forward them when i have had a chance to look them up.

Gambo

[curious aardvark]

it's included in the prusaslicer download zip file and will install if you tick the box to install it.

You've probably forgotten colin, as you were thinking about pizza at the time ;-)

useful bit of kit

if you have multimeter - just put it across the fan pins - no need to go anywhere near the big power lines.

There is also a jumper that dtermines whether it';s 12 or 24 v for fans and heaters and things.