Marlin Have some kind of heating safety feature?

Sometimes after I use my printer for a while, my electronics simply won't heat up my hotend. I'll let it rest for a while and it'll work fine again. Is this some kind of safety feature? Can I turn it off?

This might be a problem of the Ramps mosfets?

I don't think this problem is caused by firmware.

Quote
kfootball15
Sometimes after I use my printer for a while, my electronics simply won't heat up my hotend. I'll let it rest for a while and it'll work fine again. Is this some kind of safety feature? Can I turn it off?

I have had similar problem before. It may be caused by a poor solder connection between the MOSFETs and the RAMPS board. You should check the board to make sure all the connections are sound.

Eric

RAMPS = Has an undersized Fuse and a poor chosen MOSFET. You will purchase a Fuse larger than 12A. I used a 14A fuse. You will also have to purchase a new MOSFET and replace. Once those two items are replaced you are good to go.

If your bed worked for a while before and now doesn't --- It is still likely related to these two components. My heated bed did work for a few tests then didn't. So I found, figured and performed the following fix. No worries all works great!

Where to find the information???
Here 1
Here2
More Here - Complete

The last link was how I fixed my issue. You can guess and debate with many people or simply fix the two components to work properly. Note: I used one MOSFET and others found slightly better selections for a MOSFET. Mine works well so you won't be wrong. The others simply may be feature wise better and run a couple degrees cooler. Either way you are much better off with this fix and should get to temperature easily. Read the threads and you will find the Polyfuse and MOSFET to buy. They are two parts and are through hole so easy to remove and solder. There are three pins on the MOSFET and two on the Fuse. If you do this simple fix - here is a tip. --- IF you are not really adept at removing soldered components simply cut the two existing parts off at their leads with wire cutters. Then heat with your soldering iron and remove their individual leads. Then, solder in the new components. You save A LOT of time this way.


Good Luck!

Brian.

Edited 2 time(s). Last edit at 03/12/2014 11:46PM by bstott.

yes there is a safety feature. if thermister is not accurate enough and temp falls below say 5 deg c for measurement the firmware indicates this as a thermister error and does not heat up.

if you set HEATER_0_MINTEMP 0

then thermister should work as long as temp is 0 or above.

also verify that correct thermister table is used.

Edited 1 time(s). Last edit at 03/13/2014 01:56AM by jamesdanielv.

Quote
bstott
RAMPS = Has an undersized Fuse and a poor chosen MOSFET. You will purchase a Fuse larger than 12A. I used a 14A fuse. You will also have to purchase a new MOSFET and replace. Once those two items are replaced you are good to go.

If your bed worked for a while before and now doesn't --- It is still likely related to these two components. My heated bed did work for a few tests then didn't. So I found, figured and performed the following fix. No worries all works great!

Where to find the information???
Here 1
Here2
More Here - Complete

The last link was how I fixed my issue. You can guess and debate with many people or simply fix the two components to work properly. Note: I used one MOSFET and others found slightly better selections for a MOSFET. Mine works well so you won't be wrong. The others simply may be feature wise better and run a couple degrees cooler. Either way you are much better off with this fix and should get to temperature easily. Read the threads and you will find the Polyfuse and MOSFET to buy. They are two parts and are through hole so easy to remove and solder. There are three pins on the MOSFET and two on the Fuse. If you do this simple fix - here is a tip. --- IF you are not really adept at removing soldered components simply cut the two existing parts off at their leads with wire cutters. Then heat with your soldering iron and remove their individual leads. Then, solder in the new components. You save A LOT of time this way.


Good Luck!

Brian.

Have you ever checked to see if the fuse was the issue? The MFR1100 fuse is rated to hold 11amps and stated to trip at 22amps at 23c. Even at 40c ambient, its still rated at 9.4amp holding and 18.4amp trip.

I'm curious about where this Ramps board was purchased and no I do not mean "ebay", I mean the actual seller and possibly price.

Edited 1 time(s). Last edit at 03/13/2014 10:52AM by tjb1.