Trouble with my PS

Hello all,

I am having trouble with the reprap motherboard 1.2 and my atx power supply. The reprap won't turn the power supply on. I verified that the power supply will turn on by shorting pins 14 and 15 on the atx power supply connector. but when I connect it to the motherboard and flip the switch nothing happens. I have also tried a couple of other atx power supplies and none of them worked either.

Any ideas. I checked all of the solder joints and nothing is bridged and I have no cold solder joints.

Do you have a multimeter?

If so set it to resistance (lowest scale), check that the pins 14 & 15 are making a connection connection on the motherboard

If the board is making this connection then it can only really be a short somewhere on the board that is causing the PSU to not switch on (or switch on but then switch off again really quickly).

Test the +12V and 0V pins (with the power off) and make sure there is no short (if it reads just a few ohms it is a short).

You may be doing this already, but you should do all the testing without anything else plugged into the board.

There could be a bridge elsewhere on the board, other than the atx connector itself.

I think the PSU is turned on by the Arduino, have you programmed it?

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[www.hydraraptor.blogspot.com]

I did a continuity test and the pins are connected.

What I just figured out if I bypass the 10K ohm resistor (R18) by shorting the pads the power supply fires up.

What would be causing this, is it safe to remove this part and short the two pads?

I have no idea why that resistor is there. It wasn't on the previous version of the board. It is not a low enough value to turn on the PSU, you best ask Zach why he added it.

When the switch is closed the PSU is under software control by the Arduino. The standby rail powers the Arduino and the Arduino can drive pin 14 low to power up the main supply.

On the previous version, with no resistor, the PSU was clearly off when the switch was open. Perhaps the resistor was added to default it to on. Better to just wire the switch to ground it or connect it to the micro.

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[www.hydraraptor.blogspot.com]

nophead Wrote:
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> I think the PSU is turned on by the Arduino, have
> you programmed it?

Nophead,

After looking closely at the schematic you are correct pin D14 controls the power supply; I missed that earlier.

Now as far as programming the Arduino; I'm having some trouble here. I performed the Sanguino mod to the Arduino software and when I attempt to burn the bootloader I get the following error.

avrdude: successfully opened stk500v1 device -- please use -c stk500v1
avrdude: stk500_program_enable(): no device
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to override
this check.

I'm using a serial AVR ISP and had no problems with the Extruder Controller. The light on my ISP is on so I know it's getting power from the board which should mean the chip is getting power.

I think the Arduino boot stap burning process requires a special cable off of a standard PC parallel printer port.

I blogged about using the USB serial cable in bit banger mode to load the boot strap on my blog.

Which I had to do that for a Sangunio that came in without the bootstrap loaded from Makerbot.

Here's a link to the blog entry.

[exmrclean.blogspot.com]

freds Wrote:
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> I think the Arduino boot stap burning process
> requires a special cable off of a standard PC
> parallel printer port.
>
>I blogged about using the USB serial cable in bit banger mode to load the boot strap on my blog.

Freds,

Its funny that you mention this because I was actually reading that post earlier today but since I do not have a USB>>TTL cable I cannot try your method yet.

I installed AVR Studio 4 in an attempt to try and use that to write the .hex file to the Atmega644P and when I went to write it to the chip The software told me I needed to upgrade the firmware on the AVR ISP. I upgraded the firmware and then wrote the .hex file to the chip but I don't know if it loaded properly?

On the extruder controller the debug LED blinks every second but on the motherboard the led blinks 3 times and then does not blink again until you hit the reset button. Is this normal?

I ordered a USB>>TTL cable and a USBtinyISP from MakerBot Industries today and should have it next week.

Ok sounds like the extruder controller is not yet programmed and the motherboard is.

It sounds like the motherboard Sanguino chip has the boot strap that will allow you to upload programs from the Arduino IDE enviroment via the serial cable.

Did you already have an ISP programmer?

freds Wrote:
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> Did you already have an ISP programmer?


Yes I had previously purchased an Atmel AVR ISP for a project I did many years ago. It's a serial programmer but appears to work just fine. I ordered a USBtinyISP so I'll try that once I get it.