So to test with a volt meter I need to put the probes on these ports?

Or 3 and 4?

The EZB is going to be sending commands out of its transmit lead. That data will wind up on the Roombas receive lead. You don't really need to test with a voltmeter.

Quote from hardware. What do I do(If I need to do it)?

Quote:

*Note Before Connecting To EZ-B:: Check the signal wire (white wire) with a volt meter and ensure you have between zero and five volts from the Roomba. If you see higher voltage, you're connected to the wrong port. If you apply too much voltage to the the EZ-B from the Roomba, you will damage the D0 port and will require a chip replacement.

Sorry if I'm being critical here guys, I just don't want to trash 400 dollars. What do I do to check the signal voltage? One probe on the signal, the other on the gnd?

Quote:

*Note Before Connecting To EZ-B:: Check the signal wire (white wire) with a volt meter and ensure you have between zero and five volts from the Roomba. If you see higher voltage, you're connected to the wrong port. If you apply too much voltage to the EZ-B from the Roomba, you will damage the D0 port and will require a chip replacement.

Also, what would a good fuse be to put in the line?(Amperage)

To check dc voltage connect one lead to Gnd and the other to the pin you want to measure.

I get 4.59VDC which is in the range. Fuse I would say 2 amp probably.

Where are you wanting to place a fuse ? It is not needed on the Tx, Rx pins.

Ok well maybe I don't totally know what I'm doing...

Going to plug in and try it out. Please no blue smoke!