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Heatbed Problem

Posted by Sompy 
Heatbed Problem
June 24, 2016 09:16AM

I try to test the Headbed but i will not work.
The Temp Sensor shows the right Temp but when i aktivate the heatbed nothing happens.
The LED do not light up and i get no 12 V at the Inputs.
Do i have to aktivate it in the Firmware ?
Re: Heatbed Problem
June 24, 2016 09:30AM
When I first attached the heatbed, I found the site Heatbeds - A beginner's guide from the Reprap Wiki very useful specifically around the firmware settings that you have to make for a heatbed. I would recommend looking at those settings listed on the wiki page and seeing if you have them configured within your Marlin configuration.h file.
Re: Heatbed Problem
June 24, 2016 09:51AM

Thank you PDBeal
I just have checked your Link !. To me it looks like that most of the Configuration its about PID.

 #define TEMP_SENSOR_BED 11    <<< set this value to match your thermistor using a value from the table at the start of "Thermal Settings" section
    #define BED_MINTEMP 5
    #define BED_MAXTEMP 150
    #define PIDTEMPBED
    #define MAX_BED_POWER 255 // limits duty cycle to bed; 255=full current
    #ifdef PIDTEMPBED
    #define  DEFAULT_bedKp 266.49    << replace this value with the value returned by M303
    #define  DEFAULT_bedKi 49.29       << replace with M303 value
    #define  DEFAULT_bedKd 360.23   << replace with M303 value
      // FIND YOUR OWN: "M303 E-1 C8 S90" to run autotune on the bed at 90 degrees C for 8 cycles.
    #endif // PIDTEMPBED
PID autotune

But the Heatbed should work even without PID ? TEMP_SENSOR_BED is 1 ( 1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
The Board should power the Outputs ( LED Flashing ) even without PID , the Outputs for the Extruder and the FAN working fine.
I use the Firmware from Smartfriendz so i thought it should work after i pluged in the Heatbed
Re: Heatbed Problem
June 24, 2016 10:20AM
I think the Problem is the Powersupply.

Connecting Power Connect your 12V power supply to the RAMPS shield. Reversing +/- or otherwise incorrectly connecting power can destroy your electronics and cause fire hazard. The bottom pair of connectors marked 5A power the stepper drivers and Extruder heater/fan (D9, D10). The source should be rated a minimum of 5A. The pair of connectors above marked 11A power a Heated Bed, or other output (D8). The source should be rated a minimum 11A (if both power rails are connected to the same supply it should have a minimum rating of 16A).

According to the Manual from Smartfriendz you dont need to connect the two top pairs connectors ! But according to the Ramps Manual this connectors are for the Heatbed.
But there is still one Problem the Powersupply is only for 10 A Max i dont think that this will be enough !
Sorry but i have to say that Smartfriendz have to do some Homework about there Manuals !

Edited 1 time(s). Last edit at 06/24/2016 10:27AM by Sompy.
Re: Heatbed Problem
June 24, 2016 10:51AM
The powersupply unit they sent me isn't anywhere large enough to run the ramps and the heatbed either.

Although, with the kit and some of his videos, I'm not so sure the heatbed wasn't just an addition to the kit because of other people's kits. In most of his videos and documentation he talks about printing on hairspray or glue and blue painter's tape, which I tried with the Smartrap mini. However, the heatbed at 70C with my PLA sticks great and is a worthwhile addition to get working.

Edited 1 time(s). Last edit at 06/24/2016 10:54AM by PDBeal.
Re: Heatbed Problem
June 24, 2016 11:31AM
I just wondering because they sell the KIT with Heatbed and a Powersupply that cant handel thre Heatbed. Also they do not update the manual what i cant understand its just a hour of time to update the missing parts. Now i dont know what to do but i thinkling about to write Smartefriendz to get a proper Powersupply or a extra one. I ordered a Kit with anything included and this Powersupply will not work !
Re: Heatbed Problem
June 24, 2016 11:43AM
I ended up ordering a power supply from Amazon. It was cheap and its been working great so far. Fan only comes on when the powersupply needs it which does reduce the noise from the whole setup. Plus, with one this size, I'm good for other additions in the future.

I didn't have much luck getting any sort of "support" from Smartfriendz, but some of that could have been time difference between the US and France. Despite that, I'm pretty happy with the setup, enough so that I'm building a second one with much larger build area.
Re: Heatbed Problem
June 25, 2016 06:27AM
I bought my alu kit about 6 months ago. I got a mk2b heatbed. They put some little link wires between the 5A and 11A power connectors on the ramps and only ran two cables to the board, which is not good practice and the wiring to the mk2b was so small it got hot with the bed turned on. Plus the laptop style psu was not up to the job.

I agree with PDBeal get a decent power supply connect two rails one each to the two power inputs and then connect the bed with decent cables. Mains wire thickness should suffice.

Or keep the smartfriendz supply to run the 5A and get a second supply for the 11A. You could go 24v either direct for the bed only, or via a relay (there's lots of threads about this). The nice thing with the two supply via a relay is you keep all the high current stuff off your ramps board.


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Re: Heatbed Problem
June 27, 2016 07:19AM

I got a answer from Serge ( Smartfriendz ) and he was very polite like always.
He made the offer so send me a stronger Powersupply but i allready bought one at a local store.
So for me i cant say nothing wrong about the support from Smartfriendz so far !
But i would recommend to update the manual

Thank you DjDemonD and PDBeal for your Help

Edited 3 time(s). Last edit at 06/27/2016 07:21AM by Sompy.
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