How do I test for +5V on a keyboard port using a Multimeter?

Posted on 2004-10-06
Last Modified: 2010-04-25
Okay, so I'm a girl and I don't do hardware.  I'm tasked with testing a keyboard port that appears to have failed.  The directions say "use a multi-meter and check the +5V supply at the keyboard connector".  There is a diagram that shows the keyboard port, with each little hole in a circle:

   5       6

3              4

   1        2

2 = nc
3 = ground
4 = +5 Vdc (pr +3.0 or +3.3Vdc)
6 = nc

And I have this multi-meter

What do I do?  Please include instructions that say.... put the red cable in the top hole on the right, the black cable on the bottom hole on the right and then touch... blah blah.
Question by:thievesguild
  • 4
  • 2
LVL 11

Assisted Solution

mwnnj earned 225 total points
ID: 12245312
Miss thievesquild,
i haven't seen a better question than yours for a lot of time ,so i'm glad to write to you...
3 and  4 are for voltage-only to check if you have a current to your keyboard
5 is for to check the signal ,to determine for a periode of time-you "can't measure it"
1 is for the data -each botton with its meaning...
if you want to check if you have the  appropriate voltage to your keyboard,you must connect red to 4 and black to 3 ...
till later
LVL 32

Assisted Solution

_ earned 25 total points
ID: 12245663
What mwnnj said.     : )

Also make sure it is set to 20v DC for this test ( check the manual for the way to do this )
LVL 11

Accepted Solution

mwnnj earned 225 total points
ID: 12247612
That's right coral47,

the only thing is,thievesquild,you can make two checks:
once on the connector of the testing pc(what your wishing measurement is),see above and do exatly what coral47 said,use the switch on the measure-tool to make the testing -plan(circuit):
1. turn the switch,the big rotating switch to zero(OFF),you can't measure with connected wires and switch the voltage or current during the measurement -it can destroy your measure-tool!!!
2.make your testing plan:
connect black wire to COM-port(your ground) on the measure-tool ,connect the red wire to Voltage,Ohm(resistance),miliAmpere-port on the measure-tool.
3.switch the measure-tool to voltage-range DC and put it to 20V(DC) the third position from OFF-position rotating the switch to right.
Now you are ready to make your 5V-DC-measurement on your keyboard port on the testing pc!
4.connect the metal black "needle" to 3-pin (you must every time take at first ground then connect to voltage,otherwise tool damaged!),connect the red "needle" to 4-pin on the kayboard port.Look at the silicon display and see what happens,make this for 10-20 seconds-that's all.But please don't put your  fingers on the metal pins or testing-needles-your body is also a resistor -you'll receive wrong results,try to connect only metal to metal and please don't play with the testing-needles (i mean the pins from the testing wires-black and red-AVOID SHORT-CIRCUIT!
On the other way you can measure the keyboard on it's own,but you can check only the resistance from the keyboard and you need to connect it to a current circuit.
till later
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Author Comment

ID: 12250965
Thank you guys.  I tested the keyboard connector at it appears flaky.  Have to jiggle things to get it to read 5 and it fluxuates.

Sure appreciate the quick and instructive answers.
LVL 11

Expert Comment

ID: 12252178
Not at all- always welcome!
LVL 32

Expert Comment

ID: 12255866
Thank you much.    : )

Nice walk through mwnnj.   Later.   : )
LVL 11

Expert Comment

ID: 12305482
Both of us had helped!
Till next time!

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