- The LaST Upgrade -
PART 41 - USB CABLE INVESTIGATION
Last updated March 6, 2023
|Some of the printers I have used only seem to use
20cm cables as others "cause issues". I think in part it is
because of the power capability of them and the voltage drops across them
( same problems with phone charger cables). I keep looking and cannot
really find any cables with any sort of "meat" in them. They
all seem really thin and generally "un-branded". Saying that
I have a Belkin USB cable where I cannot even get the printer to connect
with it. It does look thicker than most as well. After reading countless
other issues on the net, I decided to investigate a few USB cables and
measure them myself.
This page is in no way complete or comprehensive. I just was really interested in some of the cables I had and the difficulties I was experiencing.
Belkin 2M cable
Testing the left pin, which I believe is the power ( same distance on the pin above)
|Then a right-hand pin which I believe is data.|
|Is around 0.768ohms on the power and 0.672 on the data. So if we round up to 0.8 ohms, based on 5V supply, 0.5amps, we get about 0.374V drop. So 5V - 0.374 = 4.626volts. Not great by far.|
Startech cable 1M
|Power 0.107 ohms, Data 0.207ohms. So if we take the
power resistance of 0.1ohms 5V 0.5A we get about 0.05V drop, much better!
even if we doubled the length of this cable was still only have 0.1V drop.
The Startech cable works much better, But I'm having to run through a 1M extension cable. The Belkin cable I cannot even get to connect to my printer. This cable measures 0.340R & 0.250R
At this point I am assuming the voltage drop because of the issues. *However*, my next test I'm going to connect my scope to the actual data line and see what kind of noise there is...
|Not too shabby I guess..|
|0.273R on the power. Cannot be bothered to look into this any further.|
|0.168R. Even though this cable is 2 m, if we compared to the currently best startec cable at 1M, (0.168 / 2) = 0.084R so the Roline seems to be the best overall so far.|