As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, THE SMOKE LIGHT CAME ON FOLLOWED BY EQUIPMENT OVERHEAT FIVE MINUTES LATER. DECISION WAS MADE TO RETURN WHEN THE FLIGHT INSTRUMENTS WENT DIM. EQUIPMENT OVERHEAT LIGHT WENT OUT WHEN ALTERNATE SYSTEM WAS USED. THE AIRCRAFT RETURNED TO MSP AND LANDED WITHOUT INCIDENT. REPLACED THE NR 1 AND NR 2 FORWARD EQUIPMENT SMOKE DETECTORS. ALL SYSTEMS CHECKED NORMAL.