SoliForum - 3D Printing Community — Heat bed replacement MK2a

Re: Heat bed replacement MK2a

2014-12-27T04:23:08Z

Is a SSR really necessary , when I upgrade to a Rumba board?

Re: Heat bed replacement MK2a

2014-12-03T11:11:52Z

MacGuyver20 wrote:

I did not. And I know the relay will last a lot less time. But then again it cost 5 bucks. An ssr costs 15. So in the end same price. I will look into the bang bang thing tho.

Cost is not an issue when the resulting failure can cause a fire!!

Re: Heat bed replacement MK2a

2014-12-03T04:23:56Z

I did not. And I know the relay will last a lot less time. But then again it cost 5 bucks. An ssr costs 15. So in the end same price. I will look into the bang bang thing tho.

Re: Heat bed replacement MK2a

2014-11-30T18:35:55Z

MacGuyver20,

In firmware, did you disable PWM control and revert to "Bang Bang" for the bed heater? If not, the clicking may be a bit insane and will eventually burn out your relay contacts possibly in the "on" condition...this would be bad!

Bang Bang results in a slower cycle control...the relay will last a lot longer and be safer; but at the end of the day, I strongly suggest the SSR instead.

Re: Heat bed replacement MK2a

2014-11-30T18:01:41Z

I was worried about the clicking as well. It makes less noise than the fans to cool it. The solid state relay works exactly the same it's just a little more expensive. The wiring is also the exact same just make sure you get a DC to DC solid state relay.

Re: Heat bed replacement MK2a

2014-11-27T05:29:59Z

Any possibility of photo's of the diode hook up or is it in the relay? I want to upgrade my heat bed and make sure I wire it correctly. I'm running a solidoodle 3 with the old sanguine board installed.

Also I have heard that a relay like you have posted clicks a lot and a solid state relay won't. If you were to replace your relay with a solid state relay which one would you use?

Thanks in advance.

I have found this on Ebay:
http://www.ebay.com/itm/30-Amp-Relay-Bo … 3cea59a775

I am thinking about getting 2 of these, one for the heatbed and one for the heat cartridge:
http://www.ebay.com/itm/Cartridge-Heate … 3399919631

The reason I am thinkning about 2 of them is because the original heat source for the extruder is like 3watts, so in order not to burn up the board this would solve the problem. I am just hoping that there isn't a major delay between the board registering the actual temp of the items and the control of the power to them.

Re: Heat bed replacement MK2a

2014-11-12T19:17:27Z

So for those of you who want to do this. I am posting the Parts.
Also I just kapton taped the edges of the MK2a to the metal Bed. It doesn't move, and also keeps any abs glue and shortcirquits to minimum.

The heat bed. (US supplier) $10
ebay.com/itm/MK2A-8-x-8-Hot-Plate-Heated-PCB-Platen-RepRap-Mendel-3D-NICE-US-SELLER-/181177068236?pt=LH_DefaultDomain_0&hash=item2a2efeaacc

The Relay Switch (US Supplier) $4
ebay.com/itm/Car-Alarm-30a-40-amp-Relay-Switch-Power-5-Pin-SPDT-12v-/110715685906?pt=US_Relays_Sensors&hash=item19c72b4c12

The Power!! $25
ebay.com/itm/SUPERNIGHT-12V-DC-30A-360W-Regulated-Switching-Power-Supply-for-LED-Strip-Light-/321564484058?pt=US_Lighting_Parts_and_Accessories&hash=item4adebca1da

$40 total. + wires. and quick connectors.

Also the warmup for the bed happens in 5 min to 90*C

Re: Heat bed replacement MK2a

2014-11-12T17:17:27Z

Nice! I should do this on mine. I am always worried about burning mine up as well. I did the old gobs of solder and wire tricks when I added a QUBD pad.

Thanks for the work!

Would you mind posting the part numbers?

Heat bed replacement MK2a

2014-11-12T17:04:17Z

Ok so lets start with I had a problem with not knowing the original limitations of the Solidoodle 3. Within the first 10 days I burnt out the heat bed. I kept the temperature at 90*C.
I looked for a replacement. I bought a MK2a PCB board off of ebay for about $8. Not too bad of an error or so I thought.
When I installed it i noticed that my power supply kept resetting. Basically it looked like a blink light for a 3d printer.
Ok so I tried some left over ATX power supplies I had. The problem was that I needed amperage for any MK2 heat bed, 15 to be exact. The bed itself was only about 0.8 ohms.
The next purchase was a power supply. 360W 30 A power supply again ebay for about $30. Little bit costly but atleast the rest of the printer would have more power.

This worked amazingly. I hooked it up and it ran for a solid 10 more days constantly printing. ( I got lucky with the MOSFET not buringing out early). And then blue smoke (something had burnt out).

My first reaction was to buy some replacement MOSFETs, to replace the burnt out one. The only problem with just replacing the MOSFET is you have to add a heat sink and a fan and a slew of miniature modifications, just so that this problem doesn't happen again. I hate doing things twice.

So I remembered that mosfets are basically small versions of relay switches. So I fixed the board, and then I added a relay swtich directly from the board. Make sure this relay can handle 30A(Err on the side of caution). Making sure you add a small rectifier diode so as to protect your board. The first Picture shows the Working diagram. The relay was not expensive, and an alternate would be a solid state relay, but it is more expensive. This solution has kept my board super steady and allows for a very fast heat up time.

After making sure it worked I attached it all to the frame. I have not had any problems yet.

I have attached pictures of what it looks like and the wiring diagram.