Active Cooling Fan Not Running

[Lewis Dominguez]

After having one of the wires break off of my blower fan, I replaced it with a quick connect fan from Fargo3dprinting (https://www.fargo3dprinting.com/products/replacement-blower-fan-wquick-connect-makerbot-replicator-2/), and it initially ran on startup. After trying to start a print, I noticed it was not running anymore. My DS10&DS12 lights still come on correctly when I run preheat, so I'm unsure of what's wrong. VERY new to all of this, got wrangled in to a project with the Math&Chem Departments at my college because of interest in 3D printing. I'm unsure if it'll be any help, but here's a picture of the motherboard just having booted, not running preheat or any other script.

Note: Prior to this issue, I had successful prints such as a 3D Benchy and a few models from the NIH Print exchange. Any help is appreciated!

[Lewis Dominguez]

Side note: Running Firmware 7.6. Intend to update to Sailfish proper soon, but it's difficult with the privileges on the school computers.

[Lewis Dominguez]

Just noticed the Q4 chip (resistor? mosfet? No idea) is blown, know someone who can solder a new one on, but....I've no idea what to buy to do that, or which other one on the board I could 'steal' since this isn't a rep2x, but a rep2, so there should be one for the second fan that's available to use.

[Jetguy]

Search for "MOSFET" has you covered https://groups.google.com/forum/#!msg/makerbot-users/nSI3gdb2TCo/la0bEK_S8GQJ;context-place=forum/makerbot-users

Look for the part that let the magic smoke out (smoke is put into the chips at the factory and if the seal breaks and it leaks out, they stop working).

I've circled the MOSFETs in question in red. Specifically, Q11 and Q9 control the extruder fans, Q7 controls the main blower duct on a Rep-2

I found the specifics here:

Dan Newman posted in the Tips and Tricks group in reference to a user with a 2X obviously a Rev G or H board https://groups.google.com/d/msg/3dprintertipstricksreviews/Vgq2z2_x1zc/9PfZqflsbBIJ

"The MOSFET they use for the cooling fan is a 2N7002K which is good for 60V but 
only 0.3 A. So make sure that the two fans combined use do not exceed that 
current rating @ 24V.

Be SURE you expand the quoted portions of posts because google loves to hide pictures there.

[Gian Pablo]

You can replace the MOSFET with a part in the same form factor, but 30V and much higher amperage. I forget the exact part # but it is here on the forum somewhere. I did this, worked fine, but I still ended up wiring much bigger fans to an external power supply.

[CP13]

Hi, sorry to resurrect this thread but I was wondering if anyone can help me figure out our classroom's 3d printer. I tried to swap the Q9 MOSFET to where Q7 is, but our fan still won't turn on even when the active cooling is turned active on our slicer. I bought a cheap 24v fan from Amazon so I know the fan is BNEW. Also, we can no longer print off from the SD card and the LCD screen goes black whenever we insert a known good SD card... 

Any help and/or guidance on how to fix this is highly appreciated.