Biqu b1- No printer attached?

Hi There,

I’m having the same problem someone else had a year or so ago. Unfortunately, no one responded to him so no help there.

Changed heat block/heat break throat/mk8 nozzle when threads in block finally failed after 1 too many nozzle changes. all went well for the first couple of quick test prints, then started getting what appeared to be under extrusion and a lot of stringing and blobs (PETG). played around with temp/babysteps/speed/flow etc, then decided to try a new nozzle.

When I put channel locks on heat block to steady before loosening nozzle, I noticed the block appeared loose, so shut m/c down and unplugged before pulling USB-C cable and bowden tube and disassembling hotend. Once apart noticed small amount of leaked PETG on top of heat block coming out of threads at the throat.

By now the whole assembly has cooled and tightened up and I can’t easily or safely undo throat or nozzle without likely stripping threads again.

So now it’s chicken or egg time. You cant get at the various set screws etc when the hot end is all together and you cant reassemble and tighten things up when its hot until it’s all re- assembled … ahhhh.

I decided I could install the print head off to the side of the x-carriage mounting bracket to keep it steady and secure while the (short) USB-C cable is plugged in and I could heat up the block assy while it was all hanging loose outside of the print head frame/cage and perhaps figure out what was happening in there.

After installing USB-C cable securely, I switched on the m/c and got a “printer halted kill ( ) called” message and at the top of the screen “no printer attached” message, and the printer will not work.

Any one have any ideas? I have no experience at all dealing with the internals of this thing, apart from replacing a couple of fans, the printer is stock, and has been printing fantastically and practically non stop for a year and a half or so.

Any help would be very much appreciated !!!

Not familiar with this printer but if you connect it to a computer through usb does the slicer software recognize the printer?

Good morning, thanks for your reply.

I have never connected the two and I’m just now looking into what I need to do to make it happen.

Will update shortly.

it sounds like you may have tugged a connection. there is a danger here of frying/damaging a board while working in there powered up and hot. there are 3 boards. the head has one the USB cable connected to it. there’s one at the back of the printer (inside) where everything plugs in, then the main board that the screen is also connected to. all of them are susceptible to bad connections or burned parts from being shorted. the error message is because the screen isn’t getting a response from the main board. the easy stuff is checking everything outside. the USB cable can also be a problem, I have stock on all these parts for my 2 printers, and I don’t know a way to test the cable other than trying a known good one. . when one of the boards has a problem it’s usually visible. This is probably not the solution you were looking for but check all these parts and it may reveal the problem.

When I get a clog like that I always take the hot end out and heat it externally. usually with a soldering iron to get all the globs off and with it not powered up, I just stick the iron in any place that’s metal and can heat the whole thing up enough t soften the plastic, also I can use more aggressive methods to clean the parts up without danger of shorting out a main board.

Hey there Gilengine1.

Just went thru Biqu instructions for connecting laptop to printer and there was no recognition.

I suspect that something got fried inside. Not sure where to go from here.

Thank you for your time tho!

Good morning Glenn, thanks for the reply.

Yeah, I’m pretty sure that’s what has happened.

After spending a lot of time youtubing and googling the problem and educating myself on how the internals of these things work, that’s the conclusion I’ve come to.

Now the thing I want to figure out, and I’m hoping someone can help me with, is there any way to determine/test what component(s) may be damaged without just throwing parts at this and hoping I get it on the first attempt.

You mentioned no way to test the cable, I have had a quick look at the main board and saw no sign of damage. I will be doing the same for the other components in the circuit as well today. You also mentioned that the problem is usually visible, I assume you mean burn marks, or something else?

Thanks again for your time, I will keep you posted on what (if anything) I find.

without the USB cable hooked up and if you power it on are there any lights on the main board? These were built with 2 versions of the board, you can usually read the name if it is like SKR 1.4 or 2.0 for example

Hey Glenn,

It has an skr 1.4.

As far as firing it up with no usb cable Biqu make a real big deal about not doing that, I don’t know exactly what would happen, but I have seen plenty of warnings about not doing that and I was very careful not to.

I have opened up the case and can clearly see the 1.4 marking/label on the board.

haven’t seen that but know that it’s not good to pull the cable while it’s all on for sure. anyway, is the board lighting up when the power comes on? There are no more SKR1.4 boards to replace it with so hopefully the boards ok I think you can still get SKR2 and SKR 3

This document shows where the led comes on. Bottom left corner I think
SKR 1.4 board

Hey there,

Yeah if you can give me a few min I’ll check.

I’ll get back to you in a mo.

Yeah, red light in the corner on main board and a red light on the touchscreen board.

I was just reading an article on smith3d saying to unplug bed and hotend thermister plugs at the board and fire up. if no printer attached message goes away, then just replace therm, if not (which it didn’t) then replace both.

I will check out the link in a mo. My internet is running real slow right now with this snow storm we’re getting right now.

Thanks Bud