So I thought I would get a spare Ramps 1.4 board in the parts bin just incase...

Found this, thought it was odd...

[www.aliexpress.com]

Anyone seen these?

Looking at it seems nice, get rid of the Poly Fuses and cools the mosfets much better.... I cant help but feel there is a downside here...
Why did they not put on some pins for remote reset tho......

Sadly, a major mistake made by the original RAMPS designers several years ago has been perpetuated in every revision. The mosfets on this board (STB55NF06) are a very poor choice, just like on the RAMPS 1.4 board. No reasonable electronics engineer would choose them for this application. So you can expect the bed mosfet to get very hot - just like on standard RAMPS if you don't replace it with a more suitable one. Except on this board, replacing the mosfet with a better one would be much more difficult for the average user, because it is an SMD device.

RAMPS 1.4.2 is no better in this respect, but at least it has auto blade fuses instead of the polyfuses on RAMPS 1.4. The RAMPS 1.5 board has SMD fuses, which will be a pain to replace if you blow them.

So if you are set on using Arduino/RAMPS rather than getting something that is properly designed and more powerful, at present I think the best choice technically would be to get a RAMPS 1.4.2 and replace the bed mosfet.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanx for the info...

I actually just burned my power connector up on my clone 1.4 this morning so I have it in my hands...

I am not verse on the mosfet that would be better but on this particular board I have ST-P60NF06

is that good or bad?

I was thinking the lower end mosfet issue would be ok as I have a small hotbed on this unit, only 150mmx150mm so low wattage....

Quote
JustSumGuy
I am not verse on the mosfet that would be better but on this particular board I have ST-P60NF06

is that good or bad?

I was thinking the lower end mosfet issue would be ok as I have a small hotbed on this unit, only 150mmx150mm so low wattage....

That's bad too. The problem with all these mosfets is that they are specified for 10V gate drive, not the ~5V that the Arduino provides. Any reputable electronic engineer would choose a mosfet that has a guaranteed maximum Rds(on) specified at 4.5V gate drive or lower (which implies a maximum gate threshold voltage much lower than 4V).

But as you suggest, with a lower powered bed you are less likely to have a problem with the mosfet overheating. And replacing a mosfet in a TO220 package by a better one isn't difficult. Typical good choices are IRLB8743 and IRLB3036.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

well I wont be thinking of the 1.5 with the SM fuses that is for sure.....

With my 1.4 dead now all I have in the drawer is an MKS Gen 1.4 that is essentially a Ramps 1.4 AIO setup....

After I read all your info I am very weary of the Ramps in all flavors....

I was going to use the MKS GEN in a 220x275 24v HyperCube dual Z build in the near future..... with an external mosfet for the bed....

Guess I will have to rethink that now....

Thanx for the info!!

Edited 1 time(s). Last edit at 10/21/2017 12:08AM by JustSumGuy.