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How I solved MOSFET overheating...

Posted: Tue Apr 21, 2015 8:21 am
by FugBucker
The only way I could see to solve this problem was to fit another fan. I modified a heatsink I had as well to help.

Now I have to sort out the problem of the extruder carriage gradually bending after a few hours of use....

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Re: How I solved MOSFET overheating...

Posted: Tue May 12, 2015 12:46 pm
by midiman310
Go to the "For people who wants STL files of parts " thread and print the RAMPS cooling fan STL file. It's a nice elegant solution to holding a 40mm fan in place right over the MOSFETS.

Re: How I solved MOSFET overheating...

Posted: Tue May 12, 2015 4:47 pm
by FugBucker
I have mounted a smaller fan now in the same place and cut the heatsink in half.

The heatsink does not even get warm now with the fan running all the time.....

Re: How I solved MOSFET overheating...

Posted: Tue May 12, 2015 11:07 pm
by midiman310
That looked to be a *HUGE* heatsink before you cut it in half. :) You could even get way with a lighter fan now. I used a peel and stick 5/8" heatsink and an old video card fan. Basically whatever was available in the junk box. System happy as a clam. I did however have heat saturation after printing ABS after 3 1/2 hours. I would get severe loss of steps on all axis and the program would keep printing. Happened a couple of times, always after 3+ hours of printing, and only with ABS. Found the problem to be my stock 180W power supply that came with the printer. As the power supply kept heating up from delivering what amounts to nearly MAX current for so long, the voltage finally drops off to 8.76 volts, then recovers, after about a minute. I had an older 12V/360W power supply from my Christmas LED display that I put in its place and systems been rock solid ever since. Also, I'm set up if and when I transition over to dual extruder.

Re: How I solved MOSFET overheating...

Posted: Wed May 13, 2015 9:58 am
by FugBucker
I'm playing with ABS temperatures atm. Most of my prints at 235 have that gritty effect all over them. I've been upping the temp and am at 248/120 for my current print. It looks promising and the electrics seem to be handling it. It's giving out a stronger odour though..... :shock:

Re: How I solved MOSFET overheating...

Posted: Wed May 13, 2015 11:28 am
by midiman310
It's giving out a stronger odour though..... :shock:
Yep, it sure puts out a chemical smell. First thing I tried printing in ABS was the extruder holder. So funny, as the first cut at it, the print let go 1/2 way through the job. By the time I came back to check on it, the nozzle was dragging the print around surrounded by a ball of ABS string. :lol: Got some aerospace grade Kapton tape on the glass and print sticks no problem when printing ABS. I have to remember to flip the glass over when printing PLA otherwise its next to impossible to pry the print off the tape. Yeah, so one side is for ABS and the other for PLA. Works great!

Re: How I solved MOSFET overheating...

Posted: Sat Feb 04, 2017 3:34 am
by g3gg0
thats how i solved these issues.
no fan needed anymore - mosfets get only a bit warm, not hot anymore.

http://www.g3gg0.de/wordpress/uncategor ... rovements/