I think we've fixed the burning! All I did was replace TR610, TR611 and TR612 and clean up some solder joints and no burning! Listening to music now and it's sounding sweet again. I could barely even tell at the time but I think the problem was a very small short between the solder joints on TR610 and TR611, weird it only became an issue after I had worked on the driver boards, that threw me off. I'll order a new capacitor for the phono board (I currently have the 1979 original installed) and those two zener diodes you recommend Hipocrates. Thanks heaps for the very detailed advice, now it's time to give this a good long listen to see if the protection issue is still there, I'll keep you all updated.