I think I’m almost there to fit everything together, I just want to ask a few questions before blowing anything up:
*First of all, I found 3 power supply’s laying around and I’m wondering of any of these 3 is good enough to make this setup work:
First one is a power supply of a pc:
12v 32A = 380 watt
second and third one is a power supply of an old laptop:
20v 6A = 120 watt
and
19v 4A = 76 watt (which will be not enough a assume)
will any of these 3 perform as well as the power supply’s from reichelt that everybody is talking about?
*Second question is the wiring, I drew in paint what I understand of how this mosfet has to be wired (I can be completely wrong, but this is what I understand with my basic knowledge about these things):
So on the control-board both left pins are positive and both right pins are negative, correct? Weird thing is, on the signal input is no + or - written (at least weird for me, probably this is logic for someone who understands :-))
*Final question is already stated above, even after magu’s explanation I’m not 100% sure about which jumper to connect: normal or inverted
You do not need to change the jumper settings.
The “normal” setting is ok.
Inverted means “power off when the controller board says power on”.
But we want to power on our heat bed just like the original setting.
So “normal” is ok.
You do not need to change the jumper settings.
The “normal” setting is ok.
Inverted means “power off when the controller board says power on”.
But we want to power on our heat bed just like the original setting.
So “normal” is ok.
Regards[/quote]
Ok but I Will still have to solder those 2 point together I assume. When you look closely they seem to be connected with a very small area in between. But the message clearly states to solder them to prevent damage so…
a multimeter will tell you in a second whether they actually are already connected or not.
Cheers,
kuraasu[/quote]
I know but im worried that the small connection there Will be not enough for the current running trough it, well I’ll just solder them together, then I’m sure
Routing the full current through that connection wouldn’t make sense. Those jumper pads have to be part of the control circuit, which means that there’s nearly no current.
Can you upload pictures of both front and back, with enough resolution that the component labels are readable?
[quote=“kuraasu”]Routing the full current through that connection wouldn’t make sense. Those jumper pads have to be part of the control circuit, which means that there’s nearly no current.
Can you upload pictures of both front and back, with enough resolution that the component labels are readable?[/quote]
These High resolution picture I found on the link 2stimpy provided:
I’m still not too sure on what to do, solder them together or leave them as it is…
Well, they’re not that high-res, but enough for a first look. There is one resistor visible, R7, that seems to be not present on your board. Or is that just an optical illusion?
Max current through that jumper is 12 mA (at 24 V), so no problem there.
The circuit is actually double-inverting; changing the jumper from normal to inverting cuts away the second inverter (Q2) and connects the MOSFET directly to the optocoupler.
By the way: according to Sharp’s datasheet (PC357NJ0000F), the input is polar, so you’d have to connect the wires correctly in order to make it work. The small dot marks the anode (+), which is connected to the left pin.
Well, they’re not that high-res, but enough for a first look. There is one resistor visible, R7, that seems to be not present on your board. Or is that just an optical illusion?
[/quote]
Good catch, It did not even occur to me… Now I see it too, indeed there is a resistor missing. This is not normal I assume?
That means in 1 order from reprap.me: a broken cork board and a incomplete power expander? Good reputation so far… The reason I bought it assembled is because I don’t know how to build it myself and then I get this… Well last time I got no support at all about the broken cork board, wish me luck on this one…
I’ve connected everything today and it works great. I’m using the 20v 9A laptop power supply for the heatbed.
Heating up to 50 degrees takes no time at all which is already very nice. Then I tried setting it to 100 °C and everything heats up quite fast until 85 degrees. Then it rises very very slow. 35 minutes in and it’s at 90 degrees and it seems that it won’t go over that number.
Can I get higher temperatures with a different power supply? Or is the limiting factor the heatbed itself?
actually both. The heatbed('s resistance) limits the current, and thus the maximum heating power for a given supply voltage.
In order to increase heating power, you need higher voltage. As you can see in this thread, 24 V is used most often, resulting in about 100 to 110 W heating power at room temperature and 80 to 90 W at ca. 90 °C. Since heating power increases with the square of the voltage, 20 V will result in about 70% power compared to those values.
Higher voltages may also be possible, but caution is required. Especially if the original ribbon cable is used due to its limited cross section.
After waiting for a longer time the temperature came up to about 97 °C, it’s already nice to begin with. When I come across a better power supply, I can still upgrade
I recently finished the upgrade for my bed heating. Perhaps you have read about it some posts earlier in this thread: http://forum.velleman.eu/viewtopic.php?f=53&t=9598&start=180#p50306
Meanwhile I did some successful prints with ABS. At started with 90C printing on Kapton tape on glass, but often had problems with warping and my transformer got very hot.
The I treated the Kapton with some ABS/Acetone-Slurry, since then I did several prints without treating the tape again. Bed temperature could be lowered to 83C (perhaps lower is possible, did not try yet).
BTW for the first print I used a glass plate with hairspray, as you suggested for PLA prints. But the ABS sticked so much on this that I had to break the object to get it off.
I recently finished the upgrade for my bed heating. Perhaps you have read about it some posts earlier in this thread: http://forum.velleman.eu/viewtopic.php?f=53&t=9598&start=180#p50306
Meanwhile I did some successful prints with ABS. At started with 90C printing on Kapton tape on glass, but often had problems with warping and my transformer got very hot.
The I treated the Kapton with some ABS/Acetone-Slurry, since then I did several prints without treating the tape again. Bed temperature could be lowered to 83C (perhaps lower is possible, did not try yet).
BTW for the first print I used a glass plate with hairspray, as you suggested for PLA prints. But the ABS sticked so much on this that I had to break the object to get it off.
regards
walo[/quote]
What really? ABS + hairspray sticks better then kapton? Nice, did not see that coming
I prepared a ikea mirror (the backside of it, and I sanded it) with acetone/ABS slurry. I did not tested it yet. What I did test was printing straight on kapton (sticked to ikea mirror) at 95 degrees. And with a brim, no problems. But I want to be able to print without those brims. To make ABS stick to the printbed it’s not that big of a problem then I suspected before I started experimenting with ABS. I do have some other issues like I posted in other topics: I had a jam-up when I was printing for over an hour, the finned/cooled barrel of my E3D v5 hotend became very hot and caused ABS to stick to it inside. I don’t know yet what I will do about that, probably a bigger fan or so. And the second problem (see ABS printing/config topic) is when printing small things, the layers tend to curl upwards. I think it is caused by the barrel cooling fan but I’m not sure
Oh and btw, my power supply gets warm, but not hot… But it really is a very big supply (in volume) almost twice as big as the original supply. Maybe that way it can get rid of the heat easier
Are you sure that the fan didn’t stop for a while for some reason? Today I did a larger print, an Eifel tower (not so big as yours, but still challenging ) and I checked the temperature after 4 hours of printing at 230C. It was still at 39C between the lowest two fins, which is the usual temperature. Weeks ago I was testing how much cooling is needed there and I was running the fan with down to 6Volts, resulting the temperature being still <50C. So the cooling doen’t seem to be a sensible point there as long as the fan is running a little bit.
[quote]Oh and btw, my power supply gets warm, but not hot… But it really is a very big supply (in volume) almost twice as big as the original supply. Maybe that way it can get rid of the heat easier :-)[/quote]Oh, good. My transformer is designed for a duty cycle of 50% only, this is why I avoid heating the bed to 90C. The heating would be on all the time.
Since the fan is so loud I would have noticed it when it would have stopped So I don’t think so. Yeah I really don’t know why it overheated… I have no temperature sensor to test it but I burned my fingers on it half way up, so it must have been very hot at that time. I had no issues with this before… But I notice you print at 230 degrees instead of 245, I don’t think this will make the major difference but I could try it…
so this weekend i’ll be testing it out for the first time 
) and I checked the temperature after 4 hours of printing at 230C. It was still at 39C between the lowest two fins, which is the usual temperature. Weeks ago I was testing how much cooling is needed there and I was running the fan with down to 6Volts, resulting the temperature being still <50C. So the cooling doen’t seem to be a sensible point there as long as the fan is running a little bit.