My Mendel90 won't power-up! (Solved)

Hi,

This is the first time I am trying to start my Mendel90 after assembling the kit. I have plugged in the power cable and pressed the power on button (Initialize), but nothing happens. The PSU fan doesn't start and the printer is just completely dead. I have tried disconnecting and connecting again the PSU black and PSU yellow wire, but to no effect unfortunately.

I am clueless as to what is wrong and how I could fix this, hopefully someone here would be able to recognize what the error might be. Thanks in advance for helping me.

I have attached an image of my wiring to the Melzi.

Edited 1 time(s). Last edit at 08/20/2013 07:41PM by JD1.

There are very few things that could cause that apart from a faulty power supply. One is a short circuit - does the psu fan go on with the yellow wires disconnected from the Melzi? Another would be an open circuit from a bad connection to the load resistors so I would recheck the wiring to them.

Ralph, thanks for the help. I disconnected the yellow wires from the Melzi and powered it up, but the PSU fan doesn't go on now either. The wiring to the load resistors seems to be fine, although I will possibly do a resoldering of them just to be sure. Are there other things apart from these and a faulty power supply which could cause this?

Are you sure your mains lead is not faulty?

I am not sure what you mean by "pressed the power on button (Initialize)"? The power supply should run when you switch it on with the switch on the back of it as long and the green wire is linked to a black wire. The only button is the reset for the Melzi, which has no effect on the power supply.

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[www.hydraraptor.blogspot.com]

Nophead, thanks for the reply and help. I purchased the power cable brand new a couple weeks ago and I also tried another cable from an electronics device which I know is working, but the power supply won't run.

The green wire is linked to a black wire as they are soldered to the 4R7 resistor. I haven't pressed the reset button for the Melzi, I meant the power on switch for the power supply (the switch with "O" and "I", where "I" stands for initialize).

Does this mean that the power supply itself is faulty or is there any other things apart from the above that could be causing it to not power up?

Seems like it is faulty. The only thing that would stop it starting up is a short circuit on one of the rails. If you are sure that is not the case we will send you another.

Regarding the picture you posted of your wiring. Although it looks OK, you should cut the stripped part of the wires to only about 5mm so they go all the way into the connectors to reduce the risk of a short circuit.

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[www.hydraraptor.blogspot.com]

Thanks again for the help Nophead. How would I be able to spot a short circuit on one of the rails? I have now disconnected the power supply from the Melzi and manually connected the green wire to a black wire, but still nothing when I switch it on.

Instead of you sending me another power supply, I am thinking of just picking up another PSU at my local hardware store. I can't find one with the exact number of connections as the ACE 500W, could I still use your wiring guide in the Mendel90 instructions manual and just leave the extra wires as they are and apply heatshrink to them?
The PSU I am thinking of buying is a 500 W ATX and have the following connections:
3x 4-pin Molex, 1x 3,5"-contact, 6x SATA-power, ATX 20/24-pin, 1x 4-pin P4, 2x PCI-Express 6-pin and 1x 8-pin EPS12V. Two separate 12 V cables (2x 20 A).
Would a PSU with the above specifications work?

I will strip part of the wires so they go all the way into the connectors, thanks for the advice.

Yes any ATX PSU should work. It needs to be 150mm x 140mm x 86mm to fit the brackets. The number of wires and the gauge may vary but the colours are always the same. If the gauge is thicker you will only be able to fit a smaller number in the Melzi connectors, just use as many yellow and black as will fit and insulate the rest.

For most even loading connect one of the 12V rails to the Melzi and connect the other to the red wire from the bed.

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[www.hydraraptor.blogspot.com]

I have now installed another ATX PSU and done my first print with the Mendel90 The print looked ok overall (better than I expected for my first print), although I had great trouble removing the print from the print bed. I will make another thread about this, since it is unrelated to to the issue with the PSU. Nophead, thanks again for helping me resolving this and for a nicely designed printer!