"Build It Yourself" Log

konokaiden

As for the other conversation, I had similar results as he - 0V, 3mV, 0V.

But curiously, every time I measure voltage, the value gradually goes down with time regardless of where I'm measuring. Is that to be expected, or should it plateau at a value?

daylanKifky

Hello konokaiden , I'm really sorry I missed your first question

konokaiden can follow the instructions with testing the voltage, but I could use a primer on that.

unfortunatelly the following list of measurements is not was I was looking for

konokaiden
TP1 to 2: 0V, 20kOhm
TP1 to 3: 0V, 20kOhm
TP1 to 4: 0V, 20kOhm
TP1 to 5: 0V, 20kOhm
TP1 to 6: 0V, 20kOhm
TP1 to 7: 0V, 405 kOhm
TP1 to 8: 25mV, 2.4 MOhm
TP1 to 9: 11mV, 2.4 MOhm
TP1 to 10: 50mV, 3.3 MOhm
TP1 to 11: 0mV, N/A

The idea is to measure the voltage of the Hub's power source. You have to:

Plug just the Hub (no KCs, no Raspberry) to the regular cellphone charger with the USB cable.
Measure voltage at the test point 10 (TP10 near the mini USB).
Take off the plastic Jumper at JP1 and measure voltage at the uppermost pin (be careful not to touch others with the testprobe)
Also measure the other two pins on JP1

In your multimeter: you have to select the "DC voltage mode", use one of the probes (normally the red one) to touch the indicated points while you hold the other (normally the black one) on a reference to ground.
In the Hub you will find a reference to ground at the test point 7 TP7 close to the pin header

Let me know if you need further instructions

konokaiden

Okay, so the results of that are as follows:

TP10 reads 1.23V

JP1 reads
pin A = 0mV
pin B = 3mV
pin C = 0mV

Does that help any?

daylanKifky

konokaiden

konokaiden Technically pins A and C on JP1 were +/- 0.001mV, but considering that this is the lowest possible value that my multimeter shows, it was effectively 0mV. Not sure if that makes any difference.

That's right, they are practically 0V

konokaiden TP10 reads 1.23V

There seems to be a problem here, TP10 should read the input voltage from the USB connector ~5V. There might be a shortcircuit somewhere, or a broken buck converter.
You could try unsoldering it (U2) and measure the voltage at TP10 again. If you read 5V that was the problem

konokaiden

Technically pins A and C on JP1 were +/- 0.001mV, but considering that this is the lowest possible value that my multimeter shows, it was effectively 0mV. Not sure if that makes any difference.

« Previous Page