Alternative Mosfet

Hi All,

I am continuously burning extruder heater mosfets on my Zortrax M200's, it's a total pain in the arse.

the mosfet is a B120NF10

Is there a different/heavier duty/whatever mosfet I can order to replace it?

I can solder very neatly, and have changed them already in the past, but they blow after a few weeks or so every time.

Got 3 machines affected the same way, oldest machine has never done it.

I've seen these recommended, bought some never used them. IRL3803 - datasheet shows higher continuous current rating than the one you are using.
Do you put heatsinks on them? Might be worthwhile.

Edited 1 time(s). Last edit at 07/19/2016 05:54AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

According to [www.st.com] that mosfet is in a D2pak package. Is that correct? I would be surprised if you can solder one of those without hot air soldering equipment.

The thing that stands out about that mosfet is that it is designed for 10V gate drive, however very few 3D printer controllers provide more than 5V gate drive. Even so, I am surprised that it fails so often. Does it get hot in normal use?

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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].

It does get hot yes.

Thing is that this particular machine is known for its absolute reliability, and there's only one other case of this happening known (in Brazil).

I've had 3 out of 4 machines do it in the last 6 months.

Could the power at my house be an issue?

I thought the switch mode supply would handle it all, and the guy from Meanwell Australia certainly said it should (he offered a full check of the PSU), and that by world standards Australian mains electricity was very high quality.

I'm buggered if I know why this is happening, but I need to patch them up until my Duet Wifi arrives.

No special soldering equipment was required, but I did use a piece of brass shim heavily tinned to patch the enormous burnt hole in the board. It worked about a month (as they always do) then did what all the others have, extruder temp runaway.

It's got a fan blowing over the entire board, but if someone wants to link me to better mosfets, heat sinks, whatever I've got nothing to lose.



Edited 2 time(s). Last edit at 07/19/2016 06:48AM by hobbymods.

Or this?

[www.semtech.com]

Why not replace the mosfet with whatever you've got lying around and then use a DC-SSR to run the hot end heater. Just offload the high current switching to something more capable. If it were the heatbed I'd say just use an automotive relay but since its a hot end you want PID control, mechanical relays won't work (wont work well anyway).

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Quote
DjDemonD
Why not replace the mosfet with whatever you've got lying around and then use a DC-SSR to run the hot end heater. Just offload the high current switching to something more capable. If it were the heatbed I'd say just use an automotive relay but since its a hot end you want PID control, mechanical relays won't work (wont work well anyway).

I'm not looking to modify them as it's too much drama for a simple old clunker machine like that.

I'm looking at getting a good quality, hard wired surge protection fitted to the circuit board on the house to protect all power points on that bench, as from what I'm reading it's cumulative damage that's happening.

I'll get that done then fit some new mosfets and see how I go.

Or a UPS unit?

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

If the problem is insufficient gate drive voltage then the mosfet used on the Duet should be suitable if it is mechanically compatible. It is type IPD036N04L.

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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].

@dc42: if I'm not mistaken, in the datasheet "Figure 7 Transfer Characteristics" says that 5V gate voltage is enough for 120A.

Anyway, if somebody could get a (I think Chinese?) Vanguard MOSFET (used in MKS BASE controller) it is simply amazing. I can provide the model number on my board if interested, but I cannot find it to buy it.
By "amazing" I want to say that the FLIR camera shows the temperature being lower on the MOSFET compared to the wires driving the bed or the main wires to the PSU (4 sq mm) .

LE: The model is VS40200ATD

Edited 1 time(s). Last edit at 07/20/2016 04:05AM by sigxcpu.

Quote
dc42
If the problem is insufficient gate drive voltage then the mosfet used on the Duet should be suitable if it is mechanically compatible. It is type IPD036N04L.

Thank you, I've ordered 10 of them.

I notice they are MUCH cheaper....the originals cost something like 30AUD, while these were about 1.40....is that a bad sign?

Should I be looking at surge protection still?