Heatbed 310mm Diameter Cant Reach 110c

The power to the heat bed turns off around 77c

What do you think the cause is? Is it software, transistor (If it is what should I buy or do), solider job or something else?

Info:
1. I have a pretty crappy soldier job on the heatbed for the main connectors, with a 14 (or 16?) gauge wire a foot long.
2. Also I have fan directly blowing on the transistor with a heatsink on it; however, with out that the fan on it only gets up to 44c.
3. 12v 30a Dc Power Supply.



Board
AZMSMZ
[www.aliexpress.com]

Power Supply
12v 30a Dc Universal Regulated Switching Power Supply 360w for CCTV, Radio, Computer Project


HeatBed
[seemecnc.com]

Edited 3 time(s). Last edit at 07/15/2015 04:06PM by mikes3ds.

Do you mean that the current to the heated bed shuts of at 77C, or that at full power the temperature maxes out at 77C?

---

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].

The light turns off so I assume the current shuts off. (There is led light on the heatbed)

Your firmware probably has a feature that shuts off the heated bed if the temperature isn't climbing fast enough. You might fiddle with those numbers.

Having said that, the Onyx bed can be difficult to get up to temperature. I occasionally speed it up by putting a towel or other insulator over it during the heating process...it can usually maintain temperature once it's gotten up there.

I agree it's probably a firmware feature, as the previous poster says.

If you are running it from 12V then IMO that heater has too little power for a 310mm diameter heat bed. For my delta with a 330mm diameter heated bed, I use a 300mm diameter 350W mains voltage silicone heater. Your bed heater produces only 130W at room temperature, assuming zero losses in the cables and mosfet, and less than that at higher temperatures. So about a third of the power I am using.

My suggestions:

1. Insulate under the heated bed, if you haven't already done so. You can use cork sheet, or double-later corrugated cardboard. Either way, glue a sheet of aluminium foil on top of it.

2. If you need to use a fan to keep the bed heater mosfet cool, that suggests that the mosfet isn't very good. Measure the voltage drop across it with the heater on. A good mosfet will drop no more than 0.1V @ 11A (which is what your bed heater draws @ 12V). If it drops more than 0.2V, replace it by a better one if you can.

3. If your 12V PSU has a potentiometer to adjust the voltage, turn the voltage up. If you can get 14V to the bed heater then this will increase the power to nearly 180W. Check that your AZSMZ board is OK at more than 12V. You might want to put a couple of silicon diodes in series with the fan(s) to avoid giving them much more than 12V.

---

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].

I use a dc-dc boost converter to up the voltage to my bed. I run 14v through it and it heats up to 105c in about 10minutes. Planing on wiring my bed for 24v and pumping in nearly 30v through it to reduce losses and make the converter more efficient.

---

My Personal Blog. Build blog.
[engineerd3d.ddns.net]

Modicum V1 sold on e-bay user jaguarking11

im seeing the same thing. i found out i have a Chinese knock off of the seemecnc onyx bed (wasnt intentional) and on a 12v 30a PS i can get it to 100c but thats it and it takes forever to get there. it will not go above that even if i use a towel on the bed. i am not running the power through the board either. i am running the board to a Solid state relay and powering the bed directly.

So I talked to the person who made the board, he said I need to replace my PTC Fuse with something larger right now its max current is 11amps.

Can I replace it with something like this? Or what do you think I should do?