THE MISSING DECOUPLING CAPACITOR

OK , my mod is compliant with the existing Architecture of the input buffer:


BUT....... I  cannot see any decoupling capacitor separating  the piezo line from the input network that is 4.5V VREF polarised........


 WTF?  


The 4.5 V is reaching one of the 8 pin  exiting to  connect the OP PRO CAN circuitry....


Not so healty or good circuit design.


 4.5 volt vref is reaching the dedicated piezo pin on the socket to the CAN....
.............................................so I SUPPOSE the capacitor
to be on the CAN PCB...............more than suppose .......I HOPE SO!!!!!!!!!!!

Unfortunatly then .........I need to remove the CAN and do an ispection....searching for the capacitor.


Only other explanation for not having the capacitor is that the Piezo ground is not connected to the circuit ground but instead on the VREF virtual ground..


Let's do the inspection of the can pcb then... sigh...i need to remove it...


:-((

KK

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