How to: Rewire fan connections on DB9 serial connector(Manufacturer defect)

[grobbins]

Let me start off by stating that I have confirmed not every printer's serial connector is wired wrong but at least some are including mine. I will also point you to my previous post about the fan circuitry and what is wrong and why.

http://www.print3dforum.com/showthre...nfigured-wrong

Basically in short form the 2 fans on the extruder housing on some machines may have been wired to the wrong pins on the serial connector. This in turn makes your "print cooling" fan(long ducted one) stay on constantly with no control over it and makes your "extruder cooling" fan(small ducted one on the bottom) only turn on when you tell the software to start cooling your print with your "print cooling" fan. Now this can actually lead to a big problem because your "extruder cooling" fan should always be running and never stop this fan keeps cold air blasting right against your housing and above your hotend. This is to keep a "cold zone" so the heat from your hot end does not travel up your extruder housing and start to heat your filament higher up where it will very easily become soft/melt and deform and then clog and/or jam your printer.

Now there is an easy quick fix way around this and that is to tell the printer to start the "print cooling" fan on the first layer and never turn it off and this will actually have your other "extruder cooling" fan run like it is suppose to. But the proper way to fix this take less then an hour and is pretty easy. Plus you want to have both fans running properly as well so you can turn off that constantly running "print cooling" fan for the first layer or 2 and get good bed adhesion.

First we need to disconnect both the serial connector and stepper motor connector from the extruder housing



Then to get at your serial connections just unscrew the 2 nuts and bolts that clamp the serial connector housing together and they will pop apart with the wiggling.



You will be left with all your wiring for the extruder open. You will also have to peel back about half an inch of the heat shrink covering to be able to have the wires loose enough to to work with. As you can see in the below photo the connections on serial cable go white, green, black, and red(on the front row) and red, yellow, purple, and black(on the back row) We are only going to be working on the front row of connections as they are for the 2 fans in question and in the picture above are wired backwards. The pins on the serial cable are numbered left to right and front to back 1-9 so the front row we will be working on are pins 1-5(but pin 3 has no connection as seen in the photo) and we will be ignoring pins 6-9 on in the back. Pins 1 & 2 are ment for the "extruder cooling" fan and pins 4 & 5 are ment for the "print cooling" fan.




So its really simple and need to be swapped opposite of each other so pin 1 wire will get moved to pin 5 and pin 5 wire moved to pin 1 and the same goes for the 2 other wires to each fan(negative wires). Wire 2 will get moved to pin 4 and wire 4 moved to pin 2. This you can do whatever way you like to solder but I found it easiest to unsolder all 4 pins at once by cutting off the heat shrink first and then lightly touching my soldering tip to each one to pull the wire off the pin and then re-solder each pin one by one in the proper order.

***CAUTION*** REMEMBER YOU MUST PUT NEW HEAT SHRINK OVER EACH CONNECTION TO AVOID ANY POTENTIAL SHORT LATER ON



If done properly your serial connector should run in opposite order now on the front row of connections as red, black, green, and white(like the picture below) I also confirmed this is how it is suppose to be as other members have told me theirs are wired properly this way and others as well have confirmed the same problem I had.


Also side note the wires going to the extruder's motor and wrapped really tight inside the main cable's heat shrink(almost to tight) I choose before assembling the serial connector again to pull back some more of these wires to give slack by keeping them separate from the serial connector housing there is no reason they should be crammed in there anyway and you just risk one of them breaking keeping them pulled/crammed that tight. One member has already had one of their wires break to the stepper motor because of this problem and was having trouble using the extruder properly.



Now connect the serial cable and extruder motor connector back up to your printer and power it up to connect to your software of choice. As long as you did not break any other wires while working and made sure your new solder connections were solid and heat shrinked all should be fine and when you power up your printer you will notice now that your "extruder cooling" fan is now running constantly and your "print cooling" fan is no longer and you can control it full for speed and and on/off time through your software.


I hope this helps someone somewhere down the road.

[BobenhamHotspur]

Great post, hopefully not too many people have them the wrong way (mine aren't ).

On a slight side note, I managed to break off both fans from the serial connector whilst adjusting the extruder! Those wires are like angel hair so your wiring info is going to be useful to me.
p.s. on my wires, the black heat shrink just slid up the wire so I can re-use it rather than replace it.

[BobenhamHotspur]

Another crap day

Because of my poor electrical/soldering skills it took me most of the day to attempt to fix the two fans with broken wiring but ultimately didn't succeed.

On one fan, when I attempted to de-solder the red wire it pulled away with the solder track from the surface of the circuit board attached so I believe that is now well and truly broken.

With the second fan I managed to clean enough of the solder off of the pins on the serial connector to allow me to fit tiny bootlace crimp connectors that I had crimped to the ends of the broken wires but when I connected it all back together I could not get the fan to work on either of the two fan connector pairs. So now I'm not sure if the fan is broken or if I have problems with the wiring to the other side of the serial connector.

I Googled the fans and found them available on AliExpress but they were $14 ea (£9.09) and would takes weeks by China Post.
fan.jpg

So I searched Farnell (an Element14 partner) and found a very similar (more powerful) fan for £4.01 ($6.18) with next day delivery. Hopefully I can fit the 3d printed parts to these fans without too much trouble (fingers crossed!).

For those interested http://uk.farnell.com/multicomp/mc36...05a/dp/2395864 & http://www.farnell.com/datasheets/1525903.pdf

I'll let you know how I get on.

[grobbins]

Can you post pictures of what you are describing? I do not understand when you say you pulled away the solder track from the board? there should be no reason to touch anything that is mounted on the board inside the printer. As well all of the wiring on the board is connectors and not soldered and all of this work we are looking at here involves only the db9 serial connector that plugs into the extruder.

As for soldering I did not even use anything new like added solder or remove any of the previous solder I just tapped each wire with the iron to pull it off the pin and then retapped the pin with the new wire on top until they flowed together


As for needing new fans I highly doubt that they would be actually broken Iam going to go out on a limb and say one or more of your connections you attempted is broken that is all.

If you can put up another picture that would help to explain.

[CrazyCoder]

It looks like I also have my fans reversed. If I choose to swap the connections to the main board instead of soldering the serial DB9 connector, which wires should I swap?

From the schematics it looks like these wires need to be swapped (they have different connector types, so you will have to crimp them again, soldering DB9 may be easier, but I have the crimp tools and spare metal crimps for different connector types, accessing the PCB is also very easy, just remove 8 screws from the bottom plate):

[bolsoncerrado]

May be we should even ask for an additional "tech" explanation from Rapide if there are actually so many wires "inverted", ie official fixes unless they wanna face returns in the future specially.

[BobenhamHotspur]

@grobbins - Background: While disassembling my extruder I managed to break off both of the cooling fans.

1. The print cooling fan wires pulled off of the 9 pin D connector, these are the ones I tried reconnecting using a crimped bootlace connector pushed onto the pins.
2. The extruder cooling fan (always on) wires broke just where they exit the fan casing so I had to disassemble the fan in order to replace the wiring, this is when I pulled the solder track off of the circuit board (see photos) whilst de-soldering the wire.
fan_b4.jpgfan_after.jpg

[grobbins]

Man that sucks I did not even think about the fan itself having a little pcb I figured they would of just been 2 terminal pins in the corner or something. I so far have not had to disassemble my extruder but I will make a mental note of how easy it is to break those tiny tiny wires off.

[BobenhamHotspur]

Man that sucks I did not even think about the fan itself having a little pcb I figured they would of just been 2 terminal pins in the corner or something. I so far have not had to disassemble my extruder but I will make a mental note of how easy it is to break those tiny tiny wires off.

I'd consider it a sacrifice well made if it's prevents you or anyone else from making the same mistake

[CrazyCoder]

I've checked the DB9 connector and the connectors on the board for continuity using the multimeter and my theory has confirmed. The photo of the PCB above with the red arrows showing the fan connectors is correct.

So, if you don't want to disassemble and solder DB9, it may be easier to swap the wires at the PCB side. If you have the crimp tool and the spare crimps for two different connector types (very unlikely), you can do it without soldering at all, otherwise you can just cut the wires several cm above the connectors and solder them there (a bit easier than soldering the serial DB9 connector).

Larger photo: