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RAMBO max output on FET
Posted: Tue Jul 09, 2013 5:43 am
by Michi86
Hey there,
i build up a ROSTOCK MAX with two hotends and i use for each hotend two heat cartridges with 12V/40W. Then the fuse of the RAMBO is blown up after a few minutes of heating up to 190°C. Was that too much für the board or is it possible that i have a short somewhere?
Is it better to put only one of the cartridges into one side of the hotend?
Thanks in advance!
Sunny greetings
Michael
Re: RAMBO max output on FET
Posted: Tue Jul 09, 2013 8:13 am
by Eaglezsoar
Michi86 wrote:Hey there,
i build up a ROSTOCK MAX with two hotends and i use for each hotend two heat cartridges with 12V/40W. Then the fuse of the RAMBO is blown up after a few minutes of heating up to 190°C. Was that too much für the board or is it possible that i have a short somewhere?
Is it better to put only one of the cartridges into one side of the hotend?
Thanks in advance!
Sunny greetings
Michael
You only need one cartridge per hotend. Running 4 like you are is the most likely cause of blowing the fuse. If you remove the two cartridges that do not need to be there you
will stop blowing the fuse.
Re: RAMBO max output on FET
Posted: Tue Jul 09, 2013 9:32 am
by Michi86
Ok thanks Eaglezsoar,
i thought it would be useful to speed up the heating process
But i'll give it a try to run it with one if i receive the replacement of the fuse!
Re: RAMBO max output on FET
Posted: Tue Jul 09, 2013 1:32 pm
by kbob
Michi86 wrote:Hey there,
i build up a ROSTOCK MAX with two hotends and i use for each hotend two heat cartridges with 12V/40W. Then the fuse of the RAMBO is blown up after a few minutes of heating up to 190°C. Was that too much für the board or is it possible that i have a short somewhere?
Is it better to put only one of the cartridges into one side of the hotend?
Thanks in advance!
Sunny greetings
Michael
The RAMBo is fused at 6A. 6A ✕ 12V = 72W. 4 ✕ 40W = 160W. You're going to have a problem with even one cartridge per extruder, unless the software can keep the extruders from heating simultaneously.
Your best bet is probably to get some external solid state relays.
Did you upgrade the power supply? The ones SeeMeCNC give us are marginal with a single 40W hot end (plus the Onyx bed heater, motors, etc.).
Re: RAMBO max output on FET
Posted: Tue Jul 09, 2013 1:55 pm
by Eaglezsoar
kbob wrote:Michi86 wrote:Hey there,
i build up a ROSTOCK MAX with two hotends and i use for each hotend two heat cartridges with 12V/40W. Then the fuse of the RAMBO is blown up after a few minutes of heating up to 190°C. Was that too much für the board or is it possible that i have a short somewhere?
Is it better to put only one of the cartridges into one side of the hotend?
Thanks in advance!
Sunny greetings
Michael
The RAMBo is fused at 6A. 6A ✕ 12V = 72W. 4 ✕ 40W = 160W. You're going to have a problem with even one cartridge per extruder, unless the software can keep the extruders from heating simultaneously.
Your best bet is probably to get some external solid state relays.
Did you upgrade the power supply? The ones SeeMeCNC give us are marginal with a single 40W hot end (plus the Onyx bed heater, motors, etc.).
The part number on the Wiki is 0448005.MR - Mouser shows this fuse as a 5 amp, not 6.
I believe the fuses can be replaced with 10 amp versions according to what has been posted to this forum.
Re: RAMBO max output on FET
Posted: Wed Jul 10, 2013 2:26 am
by Michi86
Oh there were a few things i don't thought about
No i haven't replaced the stock power supply
I ordered a few fuses, so i can test it with only one cartrige (12V/40W) per head and if it down't work i think i should do some replacements:
-upgrade the power-supply and maybe
-the fuse up to 10A (In
http://reprap.org/wiki/Rambo there is a remark on the fuse, that it can be exchanged for up to 10A capacity).
Additionally i look out to some smaller heat cartridges like 12V/20W or similar
