Heated bed problem

[ryho999]

Hello everyone.
I'm new to the 3d printing stuff and I'm having an issue with my heated bed. I was working fine yesterday and now it's not heating up what so ever. the temperature just stagnates at around 23 degrees. I'm worried I have a blown fuse or something in the PSU or on the ramps. pls help.

[Sebastian Finke]

You don't offer much information. First thing to check is whether you actually switched the heated bed on in the slicer...

[ryho999]

yes it is switched on. sorry I'm not really sure how properly go about this

[Sebastian Finke]

Give more information...

Printer? Firmware? Slicer?

[iDig3Dprinting]

If you have a ramps board then running a heated bed can be an issue. A common fault is that the resistor on the board gets to hot and shuts down. Having a fan blowing on the board can reduce this but in general you may need to look at an alternative wiring set up so that all of the power to heat the board is not going through the ramps, the ramps circuit is only used to turn it on. There are various different methods for this.

We cannot advise on the best method as messing with electricity is obviously dangerous and can lead to fires. I can tell you what we did but I cannot say whether this is a good idea or not you will need to talk to someone qualified in electronics.

[printbus]

The fuses on RAMPS are polyfuses - they automatically recover after an overcurrent situation has been detected. These are the large and thin yellowish square things next to the power input connections. So, we should be able to rule out a fuse on RAMPS being burned open.

Let's divide-and-conquer. Assuming your printer doesn't use an off-board relay to power the bed, the bed should be wired to the D8 output on RAMPS. The D8 output is controlled by the 3-pin MOSFET switch right beside the D8 and D9 screw terminals. The bed MOSFET switch usually has a U-shaped heatsink on it. RAMPS has an indicator, LED2, wired to the D8 heat bed output as well. LED2 is on the board, likely inside the U formed by the heatsink. Does LED2 toggle on and off as you attempt to turn the heater on and off?

If LED2 is not toggling, there's likely a problem with 12V not being applied to the 11A input on RAMPS, your firmware thinking there's a problem reading the bed temperature (e.g., bed thermistor or wiring to it is open or shorted), or a hardware failure on RAMPS.

If LED2 is toggling, your problem is downstream from RAMPS, and you have an open in the wiring to the heat bed or the heat bed itself has failed.

To help further, fill us in on important details as others have suggested. Info on how you are controlling the printer (some particular host software vs. local control panel), what firmware the printer is running, whether you have a voltmeter, size and type of the heat bed, etc. are all important to understanding what you have so that diagnostic help can be provided.