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Author Topic: 50$ robot connectivity/resistance tests  (Read 1242 times)

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Offline manutTopic starter

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50$ robot connectivity/resistance tests
« on: November 26, 2009, 12:20:14 PM »
hello,
I just finished the step 3B of the 50 dollars robot, I succeeded my "smoke test", I plugged the 4xAA battery pack holder and the 9v battery--->no smoke!! :) ..so, now, I took my multimeter and I'm ready to test the voltage, the resistance... but I'm really a beginner in electronics.. so here is a picture of how I started to test the circuit... can you tell me if the way I did it was ok..? Do I have to do other connectivity tests.?
and the last question: where do I have to put the wires of the multimeter to test resistance of the non connected pins?..which should be at least 5 kohm? can you tell me for example "multimeter red wire on H5 and multimeter black wire on K24"
thank you

the image is attached

Offline Pierre

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Re: 50$ robot connectivity/resistance tests
« Reply #1 on: November 26, 2009, 02:14:41 PM »
Very good.

     Resistors are usually check before you put it on the board.  Good to check when you are not sure of the colors.

     When you do connectivity tests, what you have to keep in mind for this board are:

     -  Ground check. There is a few(use the diode setting on your multimeter);
     -  You have a regulator. Check the output of the regulator and see if you have a 5 volts; and
     -  ISP connectors will be done when connecting to a PC.

You are doing great.  Connectivity test is really important.  Many skip the test.
« Last Edit: November 26, 2009, 02:24:50 PM by Pierre »

Offline manutTopic starter

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Re: 50$ robot connectivity/resistance tests
« Reply #2 on: November 26, 2009, 02:57:58 PM »
hi, thanx for the response and for encouragements but could you tell me (sorry..really beginner) how to do for ground check, I mean: red wire of the multimeter on...? (number and letter to locate it .. do you have noticed the letters and the numbers on the image I sent in the first post)
For the resistor, I actually checked it before putting it on the board, but I was talking about the resistance of  5 kohm of the non connected pins as said in the tutorial :"The first test is called a connectivity test. Get out a multi-meter and do a connectivity test to make sure the pins that aren't supposed to be connected aren't connected. If by chance you accidentally bridged power and ground, your circuit could spark and your batteries melt. If you put the multi-meter on the resistance setting, make sure all non-connected pins have at least 5 kohm resistance or you may have power issues"
...and also how to check if non-supposed-to-be-connected-pins  are or are not connected
..and for the regulator which should be 5V, am I right if I do like this: red wire of the multimeter on C5 and black wire on D9..?
I hope that my question is clear and thank you for future help
manu

Offline Pierre

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Re: 50$ robot connectivity/resistance tests
« Reply #3 on: November 26, 2009, 07:35:46 PM »
OK no problem

     On your multimeter, do you have diode settings?  I like to use it to see if there is a connectivity and it displays numbers plus sounds. 

     
Quote
how to do for ground check, I mean: red wire of the multimeter on...?
     What is in black are the ground(-).  One of the probes(red or black) on the set from D13 to D17 and the other probe at E13 to E17.  You should see no reading or sounds.  This would tell you that there is no connection on these two rows. 

     
Quote
..and for the regulator which should be 5V, am I right if I do like this: red wire of the multimeter on C5 and black wire on D9..?
     The regulator takes the 9 volts from pin C8(+) and D8(-). The output of the regulator should have 5 volts.  Black probe to D8(-) and the red probe to E8(+).  Should read around 5 volts.  If not then you do the troubleshooting. 

     I actually did the board few months ago.  Pay close attention on the wiring below the chips i.e.  from D17 goes to H19, H12 goes to M23.

I am not done on the $50 robots.  I am learning how to use the modified servo in C language for the ATMega8.  I am just going one step at a time.  I know electronics but require knowledge of C.

Hope this will help you.  Don't gave up.

Offline manutTopic starter

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Re: 50$ robot connectivity/resistance tests
« Reply #4 on: December 04, 2009, 08:17:22 PM »
thanx, it worked!!!  :)
my first robot works :) 
 'going to go in other parts of the forum for new little problems..

 


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