i will go directly..
there are 2 issues together i will explain them now
first , if i tried to heat just the bed from the menu
when i go there and i press to select the temperature i need , then after the press
if i turn the button instantly "the screen will shut down" not the machine you can hear the fan and voice from this power part!
it's just the screen and will open again like you just turn on the machine and says it is ready
"there are bad smell coming from machine"
so i said i will try to print without heated bed !
now there is the second issue , the nozzle will heat and home all axis and start print
just in few minutes and "the screen will shutdown and open again" like you just turn on
the print will stop you can't resume it
so i can't print anything
i checked the power supply and the man told me it's in good condition
don't know what to do ?!
I've been printing without a heated bed for a while now and it stops the shorts / restarts. Just make sure your g-code files set the bed to 0C from layer 1 and it doesn't change anywhere else. Also don't pre-heat, go extruder -> crank up ext. temp manually and don't touch the bed.
I purchased the mosfet fixed for my printers, and while I wait to get them installed I've just been printing on the cold bed. Use more skirts tho!
You've got the issue that many of us are having. The symptoms you are having are typical and they will only get worse until your printer no longer turns on. The hotbed power is connected directly to the Melzi motherboard. But the motherboard cannot handle the load. To make things worse, the connectors to the motherboard are underrated for the load. This causes the printer to exhibit these symptoms. One day my printer emitted a puff of smoke and would no longer turn on.
The solution is to take the load off the mother board before any more damage is done. There are a few techniques.
The cheap solution is to do the positive lead bypass. This is the one that I did and its working now.https://groups.google.com/forum/#!msg/wanhao-printer-3d/l6OMpiIIRSc/0C6EEcvrAQAJ
Another solution is the Hotbed Burning Terminal Fix With MOSFET Boardhttp://3dprinterwiki.info/wiki/wanhao-duplicator-i3/di3-advanced-mods/heatbed-terminal-burning-fix-with-mosfet-board/
i will go now for the cheap solution.. but is there any video or photo instructions in how to do it exactly
because i'm not so good in this things
and the link you provided it shows the final pic only :)
ok i got it .. but still one more thing " i'm so sorry fot that"
now in my machine
the +ve and -ve wires from hotbed are connected to the motherboard
if i do what you say
only the -ve will be connected
and the +ve one which is the red
should be connected to the psu!
but where exactly?! i don't get this one :(
The positive lead from Melzi at hotbed connector does not connect to anything. The negative lead from the PSU (that is shown in the drawing to go to the hotbed connector) does not connect to anything. I didn't bother attaching wires to these.
can i keep all the connections in the same way .. with just replacing the connectors with XT60 connectors ?!
You can but the hotbeds 10amps does not need to go through the V+ wire that is connected to the board. This mod halfs the amperage going through the boards V+. I personally soldered my V+, V-, and Bed V- to the boards connector pins and used hot glue to seal it up. Then connected the Bed V+ to the spare V+ on the PSU to avoid those terrible connectors the board comes with.
Have you tore the control box apart and pulled out the control board to look at that. If I were to guess you may have fried the V+ input connector to the board. I personally soldered my V+, V-, and Bed V- to the boards connector pins and used hot glue to seal it up. Then I connected the Bed V+ to the spare V+ on the PSU to avoid those terrible connectors the board comes with.