[KevinH1990]

If two clusters have had the same issue, it sounds like something is causing too much current to go to the component that is melting down. Since it only happens when you turn the lights on, I would start by checking the wiring related to the dash lights.

As Particleweave's post hints, also look at anything that a previous owner might have done to modify the car. For example, if the PO added a new stereo, he or she might have tapped into the wiring to gain illumination for the head unit. There are a lot of "hacks" that folks can do and a lot of ways for them to go wrong.

See if you can track down a wiring diagram for the cluster (I believe there is one in the Bentley manual) and then start tracing it to see whether there is a short somewhere.

Good luck.