OTGW measurements not OK

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OTGW measurements not OK

Postby Framboos » Sun Nov 20, 2016 10:59 pm

Hi,

Today I assembled the OTGW and finished the diagnostics part to be sure everything is correct. But I think there is something wrong...

The measurements (no boiler or thermostat is connected. Also USB is not connected):

Test #1: Voltage between pins 5 and 14 IC1: 5,06 V
Test #2: Voltage on X1: 23,85 V
Test #3: Current between terminals X1: 6,24 mA
Test #4: Current between terminals X1 (pin 3 = GND): 19,96 mA
Test #5: (X1 wired to X2): 6,19 V (should be a voltage between 15V and 18V) Btw, does it make a difference which pin of X1 (1 or 2) is connected to X2 (1 or 2)?
Test #6: (X1 wired to X2 & IC1 Pin 2 = Vdd): 6,19 V (so no difference)
Test #7: (voltage on pin 18 IC1, pin 3 =open): 0,000 V also one time after a while measured 2,758 V
Test #8: (voltage on pin 18 IC1, pin 3 = GND): 0,001 V also one time after a while measured 2,758 V

So test #5 and further failed.

I have checked de pcb and components but all looks fine. Also on the forum I couldn't find a solution.
Does someone have an idea what could be wrong or where to search?
Thanks in advance!

Kind regards,
Martin
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Re: OTGW measurements not OK

Postby hvxl » Mon Nov 21, 2016 4:53 pm

Mix up of D10 and D11?

If everything works as it should, it doesn't matter which pin of X1 is connected to X2 for these tests.
Schelte
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Re: OTGW measurements not OK

Postby Framboos » Wed Nov 23, 2016 5:23 pm

Hello hvxl,

Thank you for your reply! And my apologies for my late reply. I assumed I would receive an email if someone posted an answer...

I have checked the zenerdiodes but they are placed correctly. The "fat" one (BZX85C) is D10. The 4V3 version is D11. I needed a loupe the distinguish which zener is which before soldering :-)
To give more detail, the measured (cathode) voltages:

D9 (zener 4V7): 2,00 V
D10 (zener 15V): 4,84 V
D11 (zener 4V7): 4,72 V

There's no logic in it for me...

Anode side all around 0,71 V.


Kind regards,
Martin
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Re: OTGW measurements not OK

Postby hvxl » Fri Nov 25, 2016 12:13 am

In what configuration are you measuring these voltages? It looks like OK1A is switched on. That should only happen if IC1 pin 2 is pulled high. But at this point in the troubleshooting procedure IC1 should not yet be installed, and for test #5 pin 2 should not be connected to anything.

If OK1 is in a socket, can you measure the voltages again with OK1 removed? Please measure the voltages on the slave interface against GND1 (for example OK1 pin 4). It looks like last time you measured against GND, which is different.
Schelte
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Re: OTGW measurements not OK

Postby Framboos » Sat Nov 26, 2016 12:54 am

Hello hvxl,

The measurements are done with all components placed. Tests #1 till #4 should indeed have been performed without IC1 and OC1. But, according to the troubleshooting page (http://otgw.tclcode.com/debugging.html#interface), tests #5 and further, which went wrong, should be done with IC1 and OC1 placed:

"If opto-coupler OK1 was not yet installed, remove the mains power and plug OK1 into its socket. Make sure it is placed the right way around. Now use two pieces of wire to connect X1 to X2 and plug the mains power back in. You should now find a voltage between 15V and 18V on X2 (and X1). If you connect pin 2 of the IC1 socket to VDD (e.g. pin 14), the voltage on X2 should drop to between 5V and 7V."

Nevertheless, the measurements with OC1 removed:

Test #1: Voltage between pins 5 and 14 IC1: 5,06 V (still ok)
Test #2: Voltage on X1: 23,90 V (still ok)
Test #3: Current between terminals X1: 6,35 mA (still ok)
Test #4: Current between terminals X1 (IC1 pin 3 = GND): 20,41 mA (still ok)

X1 wired to X2:
Test #5: 17,03 V (is ok now)
Test #6: (IC1 Pin 2 = Vdd): 16,14 V (so is not ok)
Test #7: (voltage on pin 18 IC1, pin 3 =open): 0,000 V (ok)
Test #8: (voltage on pin 18 IC1, pin 3 = GND): 0,001 V (not ok)


X1 - X2 still wired:
The voltage on the slave interface against GND1 (OC1 pin 4): 0 V (OC1 removed)
The voltage on the slave interface against GND1 (OC1 pin 4): 0 V (OC1 placed)

D9 (zener 4V7) against GND1: 1,26 V (OC1 removed)
D9 (zener 4V7) against GND1: 1,26 V (OC1 placed)

D10 (zener 15V) against GND1: 15,00 V (OC1 removed)
D10 (zener 15V) against GND1: 4,12 V (OC1 placed)

D11 (zener 4V7) against GND1: 0,35 V (OC1 removed)
D11 (zener 4V7) against GND1: 4,11 V (OC1 placed)



I hope you can make sense out of it...

Kind regards,
Martin
Framboos
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Re: OTGW measurements not OK

Postby hvxl » Sat Nov 26, 2016 1:39 pm

OK, so you initially performed incorrect measurements due to misunderstanding the instructions. The part you quoted only instructs you to place OK1, not IC1. It does mention to connect a pin of the IC1 socket to some signal. That does not imply that IC1 should be installed at this point. In fact, it's bad practice to force an external voltage onto an output. The instruction to place IC1 is not given until paragraph 4 of the "Serial interface" chapter.

So everything actually looks good. You can continue with the trouble shooting procedure from test #5 with OK1 installed and IC1 removed.
Schelte
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Re: OTGW measurements not OK

Postby Framboos » Sat Nov 26, 2016 9:45 pm

Hello hvxl,

You are indeed right. I haven't read the instructions good enough. Thanks for pointing it out. May be you can emphasize to not place IC1to prevent others as dumb as me making the same mistake...

Rerun of the tests:
Test #5: 17,03 V (still ok)
Test #6: (IC1 Pin 2 = Vdd): 6,14 V (is ok now)
Test #7: (voltage on pin 18 IC1, pin 3 =open): 0,000 V (still ok)
Test #8: (voltage on pin 18 IC1, pin 3 = GND): 2,84 V (It's above 1,25 V but not close to 5 V. So I wonder if it's really ok)

So all looked good and I started testing the USB-interface using otmonitor.
And making a long story short: the OTGW works! (I suppose):

21:20:40.829864 Command: PR=B
21:20:40.870430 PR: B=17:59 20-10-2015
21:20:40.994335 R00000000 Read-Data Status: 00000000 00000000

Next challenges will be installing the OTGW between boiler and thermostat and how to install otmonitor on a Raspberry Pi3. For now I'm confident an OT-datastream shall then be logged.
So will be continued...

For now, thank you for your great help!


Kind regards,
Martin
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