OTGW communication lost after thermal stress

This Forum is about the Opentherm gateway (OTGW) from Schelte

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marsm2m
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OTGW communication lost after thermal stress

Post by marsm2m »

Hello,

HW from Nodo Shop.
PIC16F88P with FW gateway_v4.2.5.hex
OTGW in Gateway mode
Boiler: TERMET WINDSOR 25
Thermostat: Honeywell CT11011

Issue:
After the OTGW board is stressed with temperature about 50C the OTGW does not forward messages from Boiler to Thermostat.
After cooling down below 40C communication is OK.
Had anyone similar problems?
Could it be a soldering related issue (analog part has been presoldered)?
marsm2m
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Re: OTGW communication lost after thermal stress

Post by marsm2m »

Hello again,

the root cause for the problem was pre-soldered SMD optocoupler PC827 - most probably overheated while soldering.
To fix it I exchanged the SMD PC827 with SMD precision DIP socket adapter and used TTH variant of the optocoupler.

Hope this will help to someone who may observe similar issues.
hvxl
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Re: OTGW communication lost after thermal stress

Post by hvxl »

Very impressive that you managed to figure that one out. Thanks for sharing.
Schelte
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