HP25C repair, help needed

[albertofenini]

Thank you very much !!
I also had visited this link but I can't find a specific reference to the HP25C.
It looks, to me, that the PSU and some of the circuitry is slightly different form the HP25.
Also, if you look at the picture we posted of our HP25C and compare it to this :

it looks like our is missing an IC, just above the ACT chip.
Is that possible ?
Our board doesn't look tampered, removing a chip would have left some traces,
nevertheless it's different from the picture from the Forum, could it be a different HP25C ?
Thanks for help !!