1 Topic by Morganism

  • Morganism
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Topic: Need new mosfets--bed won't heat

Hello,

The heated bed on Solidoodle 4 stopped working. Sliced and programmed to turn on, but nothing happens. It prints fine, if I don't turnthe bed on. I know there could be other issues, but it was recommended to me to start by replacing the mosfets for the bed. I am comfortable doing this, but I don't know where to get them or what the specifications are?

Any advice/links would be helpful.

Thank you in advance...

Solidoodle 4-Mostly stock running off headless Raspberry Pi with Octoprint

2 Reply by wardjr

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Re: Need new mosfets--bed won't heat

Probably cheaper and easier to replace the board.  So many choices like Ramps or Rumba.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

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3 Reply by carl_m1968

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Re: Need new mosfets--bed won't heat

Morganism wrote:

Hello,

The heated bed on Solidoodle 4 stopped working. Sliced and programmed to turn on, but nothing happens. It prints fine, if I don't turnthe bed on. I know there could be other issues, but it was recommended to me to start by replacing the mosfets for the bed. I am comfortable doing this, but I don't know where to get them or what the specifications are?

Any advice/links would be helpful.

Thank you in advance...


If you insist on replacing them the part number is on the part. Just go to Mouser or Digikey and enter that number.

Printing since 2009 and still love it!
Anycubic 4MAX best $225 ever invested.
Voxelabs Proxima SLA. 6 inch 2k Mono LCD.
Anycubic Predator, massive Delta machine. 450 x 370 print envelope.

4 Reply by knowack (edited by knowack 2019-01-25 00:24:05)

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Re: Need new mosfets--bed won't heat

One MOSFET controls the bed heater power, another controls the hot end power; they're both an IRLB8743.

Here's one on Adafruit for $1.75:
https://www.adafruit.com/product/355?gc … 3_EALw_wcB

...and from Mouser for $1.40:
https://www.mouser.com/ProductDetail/In … Z2TQ%3D%3D

It's a pretty straightforward solder job.

Every Printrboard I've ever seen has a small piece of kapton tape over the heatsink of the heatbed's MOSFET, and none on the hot end's.  I do not know why.  The circuits for the hot end and heatbed MOSFETS are identical.  The heatsinks are electrically connected to the MOSFET's drain, and so will have 12vdc on them when their respective heater circuit is off.

As long as the heatsinks aren't touching each other, or anything else for that matter, you should be fine.

-Kevin