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matt-elkins

Heated Bed Installation Troubles

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Hey everyone, I am working with an original ultimaker. I just installed a prusa mk1 heated bed onto my machine and cannot get it to heat up!

I wasn't the one to set this up since I am not technically inclined to work on this type of thing. but i know the essence of what was done.

here is the link that i had my friend use to install the hardware: http://flashgamer.com/arduino/comments/adding-a-heated-build-platform-to-your-ultimaker

I used all of the parts listed in the directions from the link

my hb is grounded to the "diode?" i think, and directly wired to the power supply listed in the linked article

PROBLEM

Everything looks fine according to all the diagrams and forums, but the heated bed doesn't heat. The relay kicks on when it is supposed to and the extrusion head heats up.

I can't figure out if there is a wire that wasn't soldered right or if the power supply isn't wired correctly.

*When the heated bed was directly connected to the psu without the printer it would heat up, and the temp reads on ulticontroller when a lighter is held under

 

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Hi

Referring to the relay diagram in the link you provided

You should have the positive from your HB power supply going to pin 30

You should have pin 87 going to your Heated bed and the other side of your heated bed going to the ground of your HB power supply

Can you check that?

 

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This is a horrible description. You should draw it out. Is the "board" the heated bed board? Or is it the board under the ultimaker?

Negative and ground are usually the same thing. So wtf is going on?

+ should be connected to adj+. Connecting "negative" whatever that is to "adj+" sounds very very wrong and may be your only issue.

Please draw out what you describe above on paper and photograph it. Please clearly distinguish the "board" under the ultimaker from the heated bed itself.

Which of these negatives and grounds are on the UM board and which are not?

 

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I'm not happy having to translate. So... "negative" means "mk1 negative"? Why not just say so:

- mk1 negative is connected to pin 85

- mk2 positive is connected to psu (+v) <-- "adj" I think refers to that little part to the left of the "+v" section. So don't mention it here.

- pin 87a is connected to psu (-v)

- pins 86 and 87 are connected to the UM board "heat bed" port in green

Jeez - now I need to translate to the relay diagram. Okay I will get out pencil and paper and do it for you but you are annoying me.

do you own a volt meter? Did you measure the voltage coming out of the power supply? It's possible that you have to short the 3 +v pins together but you can just check the voltage at the red wire to the white/blue whire. In other words put one wire of the volt meter on +v and the other on white/blue. Do this with the relay off and then again with the relay on.

 

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OKAY so that description is horribly wrong (I mean this circuit WILL NOT WORK SO NO ONE ELSE TRY IT). Here's the schematic from the words only:

HORRIBLY WRONG CIRCUIT DIAGRAM

Now I will compare it to your pictures. REalize that making me do all this work only annoys me. You are lucky I am so helpful.

 

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Hmm. Well I can't tell which pins of the relay are which so I can't really confirm much of the circuit other than the quantities match up.

Are you sure you got the pins right? If you did it the way you described, there is no way that realy would ever turn on. It would never "click". Check your wiring again. I think you are confused about which pins are which on the relay. I know I am because I can't see the underside of the board (and I don't want to!). Just fix my drawing so it is correct (make your own please).

 

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Oh wait - I messed up. The two pins on the UM board don't simply go to a relay like I drew it.

I guess it *is* possible that this will throw the relay. But the other side of the relay doesn't go anywhere (pin 30) so you won't get any power going to the heated bed.

This is so messed up you are very lucky you didn't break anything. I'll redraw how it *should* be wired and you can fix it...

 

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I am not an engineer nor do i know how to make one of those diagrams.

Well you better figure it out. Each line is a wire. That's basically it.

Are you *sure* about those pin numbering? Are you *sure* nothing is connected to pin 30???? That's just never going to work without connecting *something* to pin 30!

 

do you mean the red wire at the psu and the white/blue wire at the relay?

Well that works also, but no, I meant the red wire at the psu and the white/blue wire at the psu.

Check the manual for the psu. I think you have to short those 3 screws together. See if it explains about the "adj" pin. Does it need to be shorted to the +V pin?

 

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It doesn't take a genious engineer to wire that up, but it does take basic electronics knowledge...

Make sure you have someone do it who has that basic knowledge. Anyone working with electricity should do fine.

/edit:

Oh, and make sure you know what type/model your relay is and get the datasheet (which explains how to connect it). Just google the model number, it's usually the first hit.

 

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I suspect all the confusion is over which relay pin is which. I think either you have it wrong, or the engineer had it wrong. I would triple check which relay pin is where and mark up your little proto board with pin numbers. Then check it again. Then check it again. It's confusing if you think the wiring diagram is top view but it is actually bottom view.

Check that when no power is applied there is zero ohms resistance (or at least less than 1 ohm) between pin 30 and 87a. If this is not true, then you are confused about the relay pin numbering. You could additionally check the coil resistance - it should be something on the order of 10 ohms to 1000 ohms. And with power off ping 30 to 87 should be an open (very high ohms) although your other electronics may make it look like as low as 3 ohms. But certainly it should be more than 1 ohm resistance with everything powered off.

I can certainly say with confidence that I have no idea where for example pin 30 is on that thing.

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