Welcome! Log In Create A New Profile

Advanced

voltage / resistance readings gen 7 motherboard

Posted by mikefiatx19 
voltage / resistance readings gen 7 motherboard
September 20, 2013 02:25PM
Hi all,
I recently finished my gen 7 motherboard and was wondering if anyone had a list of voltage test points I could use to check the board? I was doing a few tests for resistance on the board and I noticed that one of the 0.1uf capacitors that feeds the pololus has a different reading to the other three. I assume that they all should have a similar reading and I am thinking that the capacitor might be a dud. I wanted to confirm this before sucking it out and replacing it. If anyone can supply a list of test values so I can compare I would appreciate it. In all other respects the board seems to work, the Atmega is plugged in, the two power LED's are lit and the LED in the lower corner opposite the two power LED's flashes 5 times then repeats after a few seconds. I dont yet have my pololus yet so I cant test it fully. I also noticed on the link below from [reprap.org] that one side of the green jumper is designated as ground and the other side as +5v. Now, correct me if I am wrong but wouldn't jumping this connection cause a short? On my board the corner pin jump point on the Atmega is not +5v but I think this is correct and either I am reading the picture wrong or the picture is wrong. Any help would be appreciated.
[reprap.org]

Thanks guys
Mike
Re: voltage / resistance readings gen 7 motherboard
September 22, 2013 10:57AM
Quote

I was doing a few tests for resistance on the board and I noticed that one of the 0.1uf capacitors that feeds the pololus has a different reading to the other three.

Uhm, capacitors don't feed anything, they remove (or avoid) electrical noise on supply and signal lines. What you measure is not the resistance of the cap (that's always infinite), but that of the circuitry around the cap.

Quote

If anyone can supply a list of test values so I can compare I would appreciate it.

[reprap.org]

Quote

I also noticed on the link below from [reprap.org] that one side of the green jumper is designated as ground and the other side as +5v. Now, correct me if I am wrong but wouldn't jumping this connection cause a short?

You mean the dashed green line in this picture? [reprap.org]

Yes, this creates a short and this is what it should do (until the ATmega takes over this task). These 5V are a pull up resistor in the power supply.


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Re: voltage / resistance readings gen 7 motherboard
September 27, 2013 05:18AM
Thanks for the updates Traumflug,
I just assumed that as all 4 drivers did the same thing that the readings on the board would be the same between the 4 pololus. I suppose it was a bad assumption. Regarding the +5V issue, i dont have +5V in the corner pin of the IC holder (the hole you jump with ground/ green dotted line in the picture).
Although the board seems to be working. Once i have the pololus i will be able to fully test and then i can go from there.
Thanks
Mike
Re: voltage / resistance readings gen 7 motherboard
September 28, 2013 06:23AM
Quote

I just assumed that as all 4 drivers did the same thing that the readings on the board would be the same between the 4 pololus.

That's actually true. I overlooked the "one" in the original post. If you have differences between the four sockets you should have a closer look at your soldering.


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Sorry, only registered users may post in this forum.

Click here to login