MK3 Heated Bed 24 Volt heating problem

Hello people from Reprap Forum,

Problem: heated bed does not reach desired temperature (70 degrees celcius).

The MK3 heated bed:
link: [e3d-online.com]
Also a picture in the attachments

First i had the heated bed connected to my 12 volt power supply. The heating up time to 55 degrees was very long (12 minutes or so).
Now i have connected the heated bed to my new 24 volt power supply. It heats up faster but it has problems reaching 70 degrees celcius.

I changed the connection to the soldering pads. Soldering pad (2) + soldering pad (3) Ground.

I think the soldering pads are numbered from left to right according to the picture. 3 2 1

Is this good?

I also measured the voltage which is correct 24.5 volt.

What else could be wrong with my settup?

Greetings
Matthijs

Your heated bed is like mine. As your picture indicates the first single soldering pad is labeled on mine as #1 (in your picture, the pad on the right side). The one closest to it is labeled #2 and the furthest pad from #1 is labeled #3. So #1 is a single pad, and pads two and three are grouped together.

To wire 24V to them you would attach a +24v to pin #2 and the -24v to pin #3.

Hope this helps.

Hello,

Thanks for the fast response.

As i tried to explain in my question. I already did connected my wires like you explained. It is fine to hear this!

So the wiring is good i think.

Could the heated bed be faulty?

I have a 15 amp power supply only for the heated bed so i think that is enough.

any other suggestions?

Greetings
Matthijs

Quote
Viper97
Your heated bed is like mine. As your picture indicates the first single soldering pad is labeled on mine as #1 (in your picture, the pad on the right side). The one closest to it is labeled #2 and the furthest pad from #1 is labeled #3. So #1 is a single pad, and pads two and three are grouped together.

To wire 24V to them you would attach a +24v to pin #2 and the -24v to pin #3.

Hope this helps.

Hello,

Thanks for the fast response.

As i tried to explain in my question. I already did connected my wires like you explained. It is fine to hear this!

So the wiring is good i think.

Could the heated bed be faulty?

I have a 15 amp power supply only for the heated bed so i think that is enough.

any other suggestions?

Greetings
Matthijs

It could be faulty, your power supply or the board. The 24.5v you measured was that under load? (Heat bed heating up.) 15 amps is what I've got for a 24v power supply, I'm running it at 26V out (load factor). Are you running an ac-dc relay on a RAMPS 1.4? What electronics? What wiring diagram can you put up to help troubleshoot this problem.

I have mine wired up similar to this picture however instead of 12vdc it's 24vdc and my controller is a RAMPS 1.4.

Quote
Viper97
It could be faulty, your power supply or the board. The 24.5v you measured was that under load? (Heat bed heating up.) 15 amps is what I've got for a 24v power supply, I'm running it at 26V out (load factor). Are you running an ac-dc relay on a RAMPS 1.4? What electronics? What wiring diagram can you put up to help troubleshoot this problem.

I have mine wired up similar to this picture however instead of 12vdc it's 24vdc and my controller is a RAMPS 1.4.

Hello Viper,

I use a megatronics V3 which allows to have two power supply's one 12 volt for the board and extruders, stepper motors etc and one 24 volt for the heated bed.

See the attached picture for my wiring. This is what you mean i think?

That 24.5 Volts was when i started heating after about 20 seconds.

I hope this helps!

Some info of the megatronics board if you are interested:

[reprapworld.com]
[reprapworld.com]
[reprapworld.com]

Okay... what software are you running. The wiring looks okay to me so I think you're fine there. If you're using Marlin in the configuration.h there is a line of code there like this:

#define BED_MAXTEMP 150 (Mine is set to 150 so if you want you can change it to something like 115.)

If BED_MAXTEMP is less than 110 that might be part of the problem as it will cause the circuitry to cut power to the board and maintain maxtemp that you've defined. I'm not sure how Repetier does it.

Quote
Viper97
Okay... what software are you running. The wiring looks okay to me so I think you're fine there. If you're using Marlin in the configuration.h there is a line of code there like this:

#define BED_MAXTEMP 150 (Mine is set to 150 so if you want you can change it to something like 115.)

If BED_MAXTEMP is less than 110 that might be part of the problem as it will cause the circuitry to cut power to the board and maintain maxtemp that you've defined. I'm not sure how Repetier does it.

I am running on marlin.

The setting i use is ( I lowered the maxtemp from the default settings):
BED_MASTEMP 120

I have changed it now to 130

I will test this right now.

Hi,
Just my $0.02 here.
A simple method to check wiring, controller board, MOSFET, heatbed, etc.

1. Measure the DC voltage across the heatbed terminals when you are heating it, and measure the DC voltage across the power supply terminals too.

2. You should have approx. 24V DC at the PSU terminals, and a little bit less than that, say ~23.5V DC, across the heatbed terminals.

3. With the printer completely turned off, measure the resistance across the heatbed terminals. It should measure approx. 5~6 Ohms.

If any of these measured values do not match, it will tell you where the problem is.

Quote
MatthijsW
...
I am running on marlin.

The setting i use is ( I lowered the maxtemp from the default settings):
BED_MASTEMP 120

I have changed it now to 130

I will test this right now.

Unfortunately in your case this is unlikely to change anything, and will not solve the problem.

Ahh thats to bad. thanks for your help though.!

I have measured the time to heat up to 55 degrees Celsius.

From 32 degrees ( it is freeking hot here) to 55 degrees. in exactly 150 seconds. I think this is very long for a 24 volt power supply.

Greetings.
Matthijs

Quote
AndrewBCN
Hi,
Just my $0.02 here.
A simple method to check wiring, controller board, MOSFET, heatbed, etc.

1. Measure the DC voltage across the heatbed terminals when you are heating it, and measure the DC voltage across the power supply terminals too.

2. You should have approx. 24V DC at the PSU terminals, and a little bit less than that, say ~23.5V DC, across the heatbed terminals.

3. With the printer completely turned off, measure the resistance across the heatbed terminals. It should measure approx. 5~6 Ohms.

If any of these measured values do not match, it will tell you where the problem is.

I tried to solve i through vipers method to raise the BED_MAXTEMP which was already good.

I have started a print and cant measure the voltage right now.

But i already did the Ohm measurement. My Heated bed has a resistance of 8 Ohm. I have a cheap multimeter so the measurement could be a bit off.

Quote
AndrewBCN

Quote
MatthijsW
...
I am running on marlin.

The setting i use is ( I lowered the maxtemp from the default settings):
BED_MASTEMP 120

I have changed it now to 130

I will test this right now.

Unfortunately in your case this is unlikely to change anything, and will not solve the problem.

I accidentally did a reply instead of a quote so do not now if you will read my message

My 12v system does from 22C to 45C in about 3 minutes... 30 seconds more than yours does. I've never really measured how long it takes for the 24v system to kick in but I know it's under 4 minutes to 100C... so as Andrew said (and he has far more experience at this than I) it would be good to break out the multimeter and take some measurements.

Oh and as a side note, I've got a lot of really nice Thingie collections that Andrew put up for the I3 Steel (my new printer). Thanks Andrew... appreciate the sharing of knowledge.

Quote
Viper97
My 12v system does from 22C to 45C in about 3 minutes... 30 seconds more than yours does. I've never really measured how long it takes for the 24v system to kick in but I know it's under 4 minutes to 100C... so as Andrew said (and he has far more experience at this than I) it would be good to break out the multimeter and take some measurements.

Oh and as a side note, I've got a lot of really nice Thingie collections that Andrew put up for the I3 Steel (my new printer). Thanks Andrew... appreciate the sharing of knowledge.

I will borrow a good multimeter. And do the measurements that Andrew suggested.

I will also look into the Thingie collections of andrew maybe there is some inspiration for me. I designed my own printer which has a dual direct extruder and autobed leveling which works with an inductive sensor and the MK3 ALU bed. Autobed leveling ROCKS

Autobed leveling... yeah, I'm looking at some designs and I have a dual extruder setup I want to do also but the I3 steel has just been painted and I assemble the frame tomorrow (while shooting a video). My first printer BumbleBot... named after a certain Transformer is helping me build the i3 Steel version Optimus Prime Bot... heh. This is way to much fun! Let us know what you find out with the measurements. I'll check mine tonight when I get home (I have two versions of the heat bed to check but I'll post my readings resistance wise later).

Quote
Viper97
Thanks Andrew... appreciate the sharing of knowledge.

You are welcome!

Quote
MatthijsW
...
My Heated bed has a resistance of 8 Ohm.
...

24V on 8 Ohms gives you 3A, and 24V x 3A = 72W which is not good enough to heat up the MK2 or MK3 heatbeds.

Conclusion: the resistance of your heatbed is out of spec by at least 30%.

Quote
AndrewBCN

Quote
Viper97
Thanks Andrew... appreciate the sharing of knowledge.

You are welcome!

Quote
MatthijsW
...
My Heated bed has a resistance of 8 Ohm.
...

24V on 8 Ohms gives you 3A, and 24V x 3A = 72W which is not good enough to heat up the MK2 or MK3 heatbeds.

Conclusion: the resistance of your heatbed is out of spec by at least 30%.

Thanks for all the help! I was afraid this was the problem. I will contact the dealer (e3d-online.com) and ask for a new one.

Greetings.
Matthijs Worp

E3D-online.com was kind enough to send a replacement!

I will receive the heated bed next week

Quote
MatthijsW
E3D-online.com was kind enough to send a replacement!

I will receive the heated bed next week

I received a new heated bed. This one also had a to high resistance of 7.9 ohm.

I called e3d and during the phone-call they tested a couple of MK3 heated beds that they had in stock and it turns out a whole batch was faulty.

They put the product out of stock and i got a refund.

E3D thanks for the nice en kind service

Edited 1 time(s). Last edit at 07/07/2015 04:54PM by MatthijsW.