MakerGear Forum

So all the fans on my 1st gen M2 are running on 19V and they are rated at 12V, wouldn't that shorten the lifespan of the 12V fans? Can voltage be step down in the firmware?

javafuel wrote:wouldn't that shorten the lifespan of the 12V fans?

Yup, but fan abuse seems entirely too common in the 3D printing world to worry about.

Can voltage be step down in the firmware?

You can apply PWM to the fans, in the belief PWM can control the fan speed by killing the fan controller several hundred times every second while applying excessive voltage between the killings. If you're worried about fan abuse, PWM will drive you nuts just thinking about it.

You can run a 12 V fan from a 19 V supply by installing a cheap eBay buck converter between them:

https://www.ebay.com/sch/i.html?_nkw=ad ... r&_sacat=0

What you can't do is reduce the fan speed by applying PWM to the buck converter, because it only works from a constant DC supply.

Thank you. I'll pick up a buck converter. I guess the fans have always been running on 19V since day one...

I think 1st gen M2 was meant to abuse the 12V fans with 19V power. The fans are much quieter (pushing a lot less air) after I installed buck converts, but after two minutes the extruder started to extruding even though it's not set to heat up and followed by magic smoke. The smoke was from the melting extruder threads. I don't know what went wrong, all wiring seem to be correct. Everything seems in working order after uninstalled buck converters, except now the extruder is busted.

Holy smokes, a V3a in the wild?

javafuel wrote:after two minutes the extruder started to extruding even though it's not set to heat up

The heater has two wires: one to the +19 V supply, the other to the MOSFET. When the MOSFET turns on, it connects its wire to ground, so the heater sees 19 V. As the heater reaches operating temperature, the thermistor tells the RAMBo to turn the MOSFET off, which prevents the heater from getting too hot. When it cools, the thermistor indicates when the MOSFET should turns it back on.

If the wire going to the MOSFET is shorted to ground, then the heater will start heating up. However, because the MOSFET / thermistor / RAMBo aren't in control, the heater will continue geting hotter until it burns out.

So, by and large, Something Bad happened to the extruder heater wiring. You must figure out what went wrong before replacing the heater.

The sensible thing would be a V4 hot end, which may entail more hassle & expense than you really want.

I still have the original V3 hot end from my M2, although I epoxied a thermocouple next to the thermistor for comparison measurements:
https://softsolder.com/2013/05/10/maker ... e-sensing/



It got a bit messier than the photo shows, but ... for the cost of postage, it's yours. Drop me PM for the details.

If the wire going to the MOSFET is shorted to ground, then the heater will start heating up. However, because the MOSFET / thermistor / RAMBo aren't in control, the heater will continue geting hotter until it burns out.

So, by and large, Something Bad happened to the extruder heater wiring. You must figure out what went wrong before replacing the heater.

That's my guess too. I used three mini buck converters http://amzn.to/2nsXjsH . All I did is add the buck converters between the 12V fans wires and didn't touch the hotend wires. In any case, I'll leave 19V as is. 12V fans are much cheaper to replace than hotend.

It got a bit messier than the photo shows, but ... for the cost of postage, it's yours. Drop me PM for the details.

Thank you very much for the offer. I'm waiting on Makergear tech support to see what are my options are. Like insta said, it's time to upgrade the hotend. But If all fails, I'll take your offer for sure. Now I'm looking at E3D V6, it looks like it will fit on the existing filament drive. Just not sure if my 1st gen's 19V 6A power supply can drive E3D V6 at high temperature.

javafuel wrote:three mini buck converters

Remove the buck converter from the external MOSFET controlling the bed heater, because it's already running from the 12 V supply.

19V 6A power supply

The E3D V6 has a 12 V cartridge heater, so you must not connect it to a 19 V power supply.

javafuel wrote:
Thank you very much for the offer. I'm waiting on Makergear tech support to see what are my options are. Like insta said, it's time to upgrade the hotend. But If all fails, I'll take your offer for sure. Now I'm looking at E3D V6, it looks like it will fit on the existing filament drive. Just not sure if my 1st gen's 19V 6A power supply can drive E3D V6 at high temperature.

If you are printing PLA, stick with the V3a. It's a seriously good hotend, despite the age. Skip over the V3b and go straight to the v4 otherwise.

I have conversion parts to let you use E3D stuff (I used it to run a Volcano) in place of the v4 hotend if you want to. It's an incremental upgrade and uses mostly MG parts.

I print mostly in ABS and don't really print all that much. Both E3D and V4 options require more mod time than I have right now. For the time being, I'll take on Ed's offer and will look into upgrade to 24V setup later. Thanks for all the inputs.