Those values look reasonable to me. I’m not 100% clear which points some of your measurements refer to, so I’ve modified your images to include arrows pointing to where I think you’re measuring.
The important thing to calculate is the current through resistors R5 and R11. In the ON state, the top switch should be off and therefore the current through R5 should be close to 0 and the current through R11 should be ~10mA. You mentioned that the GND should be 0V in the ON state (I agree), but I’m assuming that the 3.29V you measured is on pin 4? I expect the GND node (the opposite end of R11) to be at 0V. Is that correct? If so, that would make the current through R11 ~9mA, which would indicate that the bottom half of the switch is in the ON state (which it appears to be, since the resistance between pins 5 and 6 is 76 Ohms). So far, this looks good to me.
I’m not clear where the 1.37 V measurement refers to, but if it’s at pin 1, that would make sense. In this case, the current through R5 would be ~10mA (which means that the top switch is on, in agreement with the 76 Ohms between pins 7 and 8). The bottom resistor, R11, looks like it has 0mA across it which is also the expected behaviour.
Assuming my interpretation of you’re measurements is correct, things looks ok to me. If the output pins have the correct resistance (~76 Ohms between the pair that is supposed to be on, and > 1 MOhm between the other pair), I wouldn’t expect you to have any problems.
Have you re-run the “Test channels” diagnostic after swapping out those relays? Did you see any changes?
On Fri, Apr 24, 2015 at 4:01 PM, Linh Tran dlin...@gmail.com wrote:
Thank you for your troubleshooting instructions. That is very helpful!
For all of our 3 boards, I have measured the voltages of the **pins 1-4 **(referred to the ground at the 2 middle pins of J1) and the resistance of the pin 5-8 for all switches and I got:
Do those values look normal for you? For me I guess it is not normal because in ON state, the GND should be 0V. So I have removed the switch CH76 & CH77 (which were giving no capacitance in the previous test) and measure the voltages again but nothing changed. And I am wondering why in OFF state, pin 1 was not 5V but only 1.37V.
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