Printer stops after 1 1/2 hours printing

Hi,I have a chinese Aurora I3,modified with wade,s extruder,Ramps 1.4 electronics,Marlin fw.
Whilst doing a 2 hour print of a Bowden type extruder in PLA,at 185C and bed 50C,the printer stopped dead at about 1 1/2 hours.
I had been printing with Pet-G before this,at 240C,and bed 50C,and had frequent problems with the printer stopping,due to max temp.shutdown.
Has this fried the ramps fuses,or is it more likely the mosfet?I do have a heatsink on it,and a 80mm fan blowing over the board.
I have noticed that the power supply makes a horrible grinding noise when starting up,though that goes away after about a minute's running.
I have a 60A server power supply,which i could substitute,but don,t know if this has any relation to the shutting down problem.
Any thoughts?

Are you driving the printer via USB using host software running on a PC?

If you have an SD card slot on the printer, try printing from it.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I did have an lcd screen with sd slot originally,but it died very quickly.
so i'm using my laptop with pronterface.

You have to figure out if the problem is in the printer or in the USB connection or the computer. USB connections are notoriously unreliable when driving 3D printers for a long time.

Is your laptop set to power down after a certain period of disuse? Did it power itself down and reboot for a security update?

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I have set the laptop to never sleep or standby.It has always worked reliably before,so i had no reason to doubt it.
It's not connected to the internet,so can't do updates unless I bring it within range of the wifi modem.(it lives in the workshop with the printer).
I have a spare ramps set that I bought to make a new printer,so I'll swap that out for the old one,and see what happens.
I could try a different usb port on the laptop too,as well as another power supply.
When all is said and done,it,s only a machine,right?

It's only a machine at the mercy of the software running on it...

There are so many ways for a computer to screw up a long print that it may take you years to find and fix them all. I gave up a long time ago and just print from SD cards. They are far more reliable than using a USB connection from a computer that's doing 50 other things while it's running your print.

Edited 1 time(s). Last edit at 10/20/2016 12:11AM by the_digital_dentist.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Would this:[my.aliexpress.com]
gadget be a reliable way to add sd card support?
Or is there a better way to do it?thnx.

Bad link.

I don't think anything you get via Ali-express is going to be a reliable way to do anything.

Max temp shut-down implies that there's a problem with the thermistor connection. Thermistors have a negative temperature coefficient- the resistance drops as the temperature goes up. Max temp shut down suggests a shorted thermistor. Check the wiring from the controller all the way to the thermistor.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

max temp errors can also be caused by EMF radiation from nearby PSU wires, may want to make sure your thermistor wires arent too close to any 12v lines (running them near heater wires should be fine)