hello,
I have a defective power suply, I have the same problem as this viewtopic.php?f=48&t=13907.
Now I have ordered a 15V-100W and a 100W 24V power supply.
but now my question is what pcb can I use best.
eytec pcb layout or Edirol layout ?
the SFH 618A-1, however I can not find, is there an alternative?
anyone has the eagle files for this pcbs?
[quote=“D.K”]hello,
I have a defective power suply, I have the same problem as this viewtopic.php?f=48&t=13907.
Now I have ordered a 15V-100W and a 100W 24V power supply.
but now my question is what pcb can I use best.
eytec pcb layout or Edirol layout ?
the SFH 618A-1, however I can not find, is there an alternative?
anyone has the eagle files for this pcbs?[/quote]
You can also use a simple relay to switch the heatbed.
Just put a resistor in series and a diode antiparallel to the coil.
I found everithing and ordered the components for eytec his pcb can somebody post a picture of the ready fitted board ?
i have ordered the components and build the schematic.
But it doesn’t work. I think the mosfet is not triggered.
i have a IRLR8743PbF.
In the datasheets i see this connection numbers.
|| | = S
D || |
|| | = G
Am i right?
when i measure it seems the optocopler get triggered.
Bu the mosfet don’t
checked everything and can not find any mistake.
The optocoupler i have is an SFH610A-1
But i saw in the wiki they use a SFH618A-1, does this matter=
question:
the back of the mosfett is that the same connection as the little pin in de middlle?
And how can i test if the mosfet realy works?
After 3 days found the solution.
in the mean tin i had replaced the optocoupler and mosfet, and also tested the mosfet and optocoupler. but they where all ok.
Then i checked the resistors.
i have a large collection resistors, each value in its own box.
i have changed the values 2,2ohm with 2,2kOhm, very stupid of me.
so in the diagram i had placed a 2,2 ohm resistor instead of 2,2Kohm.
when i had changed the resistor everything worked.
My heatbed is within a few minutes on 50 degrees. 
Im having some bad luck but with ATX PSU’s. It seems they dont like PWM pulsing?
I was using a noname 800W PSU that at the same time powered my printer and a home theatre pc thats always on, it ran for a year with no problems.
When I moved the printer to another room, I took the PSU with it, so it only powered the printer (and an old cdrom I added to have something on the 5V, just in case). Within a few hours of printing the PSU died. When disconnected, the PSU still turns on, provides 12V, but the moment I connect any load (even the cd rom), it powers itself off.
So I got another PSU I had laying around as spare, this time an Antec 550W trio (3x 18A on 12V). Within less than an hour of printing, the exact same thing happened with the exact same symptom: psu runs, until you load it, then it shuts off. Funny that?
For the record Im using an E3D hotend thats designed for 40W@12V, edirol’s relay scheme to power a Mk I heatbed which pulls ~90W @12V. I intended to power it with 24V but didnt get around doing that yet.
Since it worked for so long when it also powered a PC, could it be these ATX PSU’s dont like pulsing between high and virtually no load? Or do I need a larger load on the 5V?
edit: looks I spoke too soon. When I hook up an old harddrive to the Antec, it seems to work. Cant test properly as I butchered my thermistor, will report back.
hello I have edirol pcb made but I do not know which pins I need to connect the controller board to x1 on the PCB board , is this just a plus and a minus or all four pins that I need to connect to X1?
thank you in advance
You don’t need to connect all four pins (one + and one - is enough). But you have to respect the polarity (the plus must be connected to R1).
To folks in the US, NTE parts are fairly easy to obtain, and I didn’t want to adjust resistors to compensate for voltage levels on the bed side of the circuit. So, I decided upon the following circuit:
Everything to the left of D5 will work passively on a small heat sink, when driven with only 20V to the bed. To the right of D5 is a temperature controlled fan switch that should trigger around 40*C. Make sure that the thermistor is in contact with the heat sink for Q1. Here’s a board that I made to put it all together:
I’ll post gerber files after I’ve modified the layout to support use of NTE498 heat sinks. The sinks I’m using were random salvage from a junked printer.
I’ve build the edirol’s circuit (using raw perfboard and an awful wiring on the backside) with a small modification :
I’m using an universal laptop power-supply which automatically selects the voltage using a resistor located inside the various plugs.
So I dismembered a plug to only keep the power-supply side and remove the resistor and I added a 6.8k and a multi-turn variable resistor on the circuit between GND and “sense” wire. This allows me to change the voltage from 16V to 24V (6.8k was my power supply resistor for 24V which is the max).
at 17V, it takes more than 14 minutes to heat to 60°C, at 19V, this drop to 9 minutes 30 seconds and to 6 minutes 15 seconds at 22V… I won’t try to go to 24V as the power supply is only rated 120W and I don’t want to push it too much as prints can take many hours… and as I use a mirror to print, the little delay allows the head to better flow in the glass (which is a poor heat conductor).
PCB is 2.5cm wide so I’ll be able to “hide” it on the main frame. And using the same connectors than those already present make it a reversible change.
Thanks again to edirol for his schematic.
Vapula, your time measurements seem consistent with mine; however, you have not mentioned ambient temperature.
As long as you don’t exceed the gate voltage and maximum junction temperature of your selected power MOSFET, then you should be alright. Since your thermal profiles have similar wait times (your post lacks information to verify differential values), I shall assume that your interface board is working as it should and your bed heater’s resistance is similar to mine. My bed measures 5.0 Ohms resistance at 12C, which puts it right about 6 Ohms resistance at 60C. Your power supply is capable of 24V, which means 115.2W at 12C and only 96W at 60C. Looks like you can run full power.
My prototype is complete, and fully functional; however, I decided to look at the datasheet for edirol’s choice of MOSFETs (IRLR8743). The first thing that I have to say is that that MOSFET has some nice characteristics! In fact, I may not have needed any sort of active cooling, had I chosen to follow that route. I’m also going to purchase a few of them soon.
Like I said, if you are in the US and need to purchase parts retail (Fry’s or other suppliers), my diagram gives a fully functional circuit using NTE parts. On the other hand, my power MOSFET choice has a relatively high Rds compared with that of the IRLR8743. I’ll leave it at that for now, since I’m having some typing issues at the moment.
Hi all, I know it’s a bit late coming to the party, I have just finished reading this thread and need a clarification please if there is anyone about.
The connection in this image below shows the leads from the power expansion board going to the Heater2 connector on the controller.
lh4.googleusercontent.com/-y-9z … keling.png
Am I’m right in thinking that this connector is the one that connects the original heatbed by the two groups of 4 wires reducing to two terminating at each pin. If so can I use these wires (still as groups of 4, and connected to Heater2) to connect the power expansion board, or do I need to run two single wires as shown.
Many thanks.
If you want to keep the connector, (which is what i assume)
you surely can reuse it. Just make sure to get the polarity right and group the leftmost (+) and rightmost 2 (-) pins together.
The connector only has 4 pins to spread the load over 4 instead of 2 pins.
Hi ALL!
Have a question regarding Power Supply… I have 230W power supply for HP All-in-One. However the output is 18V instead of 15V. Can it be used as a “direct replacement” or should I build some kind of circuit to lower the voltage?
[color=#BF0000]NEVER[/color] power the controller itself with over 15V!
What you can do, (altough it won’t give much improvement) is to use your 18V Supply to power the heatbed alone.
Thanks. So, to keep bed with external power supply, controlled by the board. Could a simple relay (mechanical or electronic) be used? Or board like shown previously should be used?
PS. Found an answer in previous posts. Thanks everyone.
[quote=“ichbinsnur”]If you want to keep the connector, (which is what i assume)
you surely can reuse it. Just make sure to get the polarity right and group the leftmost (+) and rightmost 2 (-) pins together.
The connector only has 4 pins to spread the load over 4 instead of 2 pins.[/quote]
Thanks ichbinsnur, that will save me using two new wires to connect to the Power Expander.
Wouldn’t a reprap power expander be really all you need to add a 24v power supply to the heatbed? I don’t know this is a question, From my understanding 24v in out to heatbed and then out to the controller. Am I wrong?
I have completed installing the Mk3 heatbed in this configuration. lh4.googleusercontent.com/-y-9z … keling.png
Unfortunately, when all is powered up, I’m getting a ‘error maxtemp bed’ on the LCD and ‘error maxtemp triggered’ warning in the log.
With Repetier Host connected I’m unable to move any of the axis and the bed reads 155.40c although the bed itself is cold.
I have meticulously check all the connections and wiring and I’m 100% sure I am good to go.
I’m unsure as to where I go from here. I have a feeling that the problem is with the firmware, if it is I know nothing about the code. Any help would be appreciated. Thanks.
