OTGW power problem

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Moderator: hvxl

OTGW power problem

Postby stoffel67 » Thu Apr 21, 2016 1:47 pm

Hello

I am new to OTGW, I got a new heating (ELCO Trigon S with QAA73)
and I want to monitor the heating.

I bought a OTGW Board and assembled it.

I did all the checks from this side. http://otgw.tclcode.com/debugging.html

All checks are OK, all current are within the mentioned range.

Until:
until I put in den PIC16F88!
before the voltage on IC1 between pin5 and pin14 is 5,05V
after mounting the PIC, the voltage drops to 1.25V


I conneted a USB-TTL adapter this way: (without 230V power connected)
IC2 USB-TTL
PIN 11 TX
PIN 12 RX
PIN 15 GND
PIN 16 5V

Connection with Hyperterminal, I get the following output

OpenTherm Gateway 4.2.5
Thermostat disconnected
R80000100
R80000100
R80000100
R80000100
R80000100
R80000100
....

So the PIC16F88 seems OK,

there must be something wrong with the power supply between IC3 and IC1


What went wrong? where can I start to look?

Please help....

kind regards
Stefan
stoffel67
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Re: OTGW power problem

Postby hvxl » Thu Apr 21, 2016 5:03 pm

The PIC wouldn't run on 1.25V, so the most likely problem is that you miscounted the IC pins.
Schelte
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Re: OTGW power problem

Postby stoffel67 » Thu Apr 21, 2016 7:51 pm

Hi Schelte,
great tool you have designed... I am impressed...
I believe I found the error:
The 7805 has disfunction.... evertime I mount the PIC the voltage drops down...
I dissasembled the 7805 and tried with an LED ... same effect... voltage is dropping...
I soldered another one and VOILA:
I get:
OpenTherm Gateway 4.2.5
Thermostat disconnected
R00000000
R00000000
R00000000
R00000000
R00000000
R00000000

I believe this is OK?

Now next action:
I need to open the boiler and look for the X1 Connector.
Do I need also to connect the Thermostat (X2) or can the OTGW run without Thermostat?

kind regards
Stefann
Last edited by hvxl on Sat Apr 30, 2016 9:00 am, edited 1 time in total.
Reason: Removed a control char that made the RSS feed produce invalid XML.
stoffel67
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