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Relay switch addition to prevent heat bed cutting out

Discussion in 'Mods and Upgrades' started by Jerry RoBo 3D, Nov 23, 2013.

  1. Ziggy

    Ziggy Moderator
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    Probably an even better choice of Mosfet is IRL1404 (from the International Rectifier selection guide).

    Vdss = 40v, Ultra low on resistance = 4 mΩ, Imax = 160A and it is a logic level device with Vgs gate threshold between 1-3 v.

    Readily available on eBay too.
     
  2. warlocke

    warlocke Active Member

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    The new part number is IRLB3036PBF
    :)
     
  3. Brian Stott

    Brian Stott New Member

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    @ ziggy & warlocke --->:D
     
  4. uniman2

    uniman2 New Member

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    i had a question on the RGEF1400 polyswitch. are the two polyswitches on the board the same? or is there another one i should purchase? i ask this because both polyswitches on my board have completely different number. Thank you for any help
     
  5. Lew

    Lew Member

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    I am having the same problem with the heated bed suddenly cutting out and dropping the temp. Although I am printing in PLA only, I find that without the heated bed I do not get a reliable stick to the bed. The bed is level and get a good pattern on the skirt. So now after 5 minutes or so, the extruder catches on a tiny piece and drags it around.

    So I am interested in the solution to the PTC dropping out. I am also trying to print out the fan mount for the Arduino board, but without the heated bed, I have failed to print it several times.

    Has anyone determined a satisfactory PTC replacement, either from Mouser or Digikey?
     
  6. SteveC

    SteveC Well-Known Member

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  7. Lew

    Lew Member

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    Thanks. Looks like I may have sharpen my electronics skills.
    But some good news. I raised the printer up on 2X2 boards and placed an old computer fan under the printer blowing up on the PTCs. That has kept them from tripping out until I find a more permanent solution.

    I'm printing again!!!
     
  8. Bob64

    Bob64 Member

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    No. The two fuses are NOT the same. Source: http://reprap.org/wiki/RAMPS_1.4#F2_-_MFR1100_Fuse
    look at the part numbers between the F1 and the F2 fuse. not the same.

    As far as I know, the only one tripping early is the F2 fuse. Correct me if I'm wrong, but from what I've been reading you don't need to swap out the F1 fuse.
     
  9. SteveC

    SteveC Well-Known Member

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  10. Bob64

    Bob64 Member

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    Which mosfet did you replace? Is it Q1, Q2 or Q3?

    Edit: Nevermind. Looks like it is Q3 for anyone else that had the same question.
     
  11. SteveC

    SteveC Well-Known Member

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    Bob, It should be Q3. Its the one tied to +12V2 and drives the bed heater.
     
  12. warlocke

    warlocke Active Member

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    Ok, so I finally got around to ordering and replacing the parts for my Ramps board.

    I used:
    RHEF1500CT-ND 15a Polyswitch for F2
    IRLB3036PBF MOSFET N-CH for Q3

    Cranked the bed to 100c and they work like a charm. The polyswitch only gets slightly warm to the touch and the MosFet has no noticeable heat whatsoever. The bed stays rock solid at 100c.

    heatbed_stat.png
     
    2 people like this.
  13. Brian-UK

    Brian-UK New Member

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    Hi all I can't find a IRLB3036PBF MOSFET N-CH anywhere just to check has anyone installed the IRL1404 and if so how's it running? I need to fix this quickly my head bed trips out every print. I have the new fuse ordered and today I picked up a 40mm fan (although after slicing the bracket in slicer the print was all over the place not sure why that was). I also have some PLA on order which hopefully I'll be able to use until I get this sorted.

    Thanks

    Brian
     
  14. Ziggy

    Ziggy Moderator
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    I've installed an IRL1404 (with heatsink of course) and it runs a lot cooler than the stock. This MOSFET is cheap and readily available on eBay.

    Z
     
  15. Brian-UK

    Brian-UK New Member

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    Awesome I have one ordered I'll install it soon as t arrives.

    Thanks :)

    Brian
     
  16. Jeff Mercado

    Jeff Mercado Member

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    I just installed a IRL3036 and as Brian notes above, the ambient temp was 18C and it only raised to 28C with the heat bed cycling (less than 10A average) to maintain 100C. Thanks for the education and math lesson Brian, it worked well for me and I benefited.
     
  17. Qhuy

    Qhuy New Member

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    Can I use MOSFET k1388 to replace the Q3 MOSFET? Attachment of the spec for MOSFET k1388 below.
     

    Attached Files:

  18. SteveC

    SteveC Well-Known Member

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    I'm using the irlb3036pbf mentioned above by warlock: http://www.datasheet-pdf.com/datasheet/InternationalRectifier/643573/IRLB3036PBF.pdf.html . It's Rds (at 2.8 mOhms) looks to be about 10x lower than the 2SK1388 (at 37 mOhms) and it has a much higher max power dissipation. I had no problem getting the IRLB3036PBF. See Brian's calculations above for the MOSFET's power dissipation and temperature rise. The 2SK1388 seems really close to the stock part and will get hot.
     
    #78 SteveC, Jul 22, 2014
    Last edited by a moderator: Jul 23, 2014
  19. Qhuy

    Qhuy New Member

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    Thank you, SteveC.
     
  20. felixkalm

    felixkalm New Member

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    My readings for the bed were fluctuating and have completely flat lined since then. Ive felt the polyfuse, doesn't feel hot at all. The polyfuse I have is the 14A one do i need to swap it out for a 15A one? This is the text on the MOSFET p55nf06 g40t9 v6 chn 312. Also mine had a built in fan over the polyfuse, i'm not eaxactly sure what to do the bed reads at 0 degrees.
     

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