As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PART WAS INSTALLED AROUND TACH AND CONNECTED TO REOSTATE FOR THE INSTRUMENT LIGHTS. IT SHORTED OUT THE SYSTEM AND BURNED OUT REOSTATE-S2091-5 AND POWER TRANSISTER 2N3055. THIS CAUSED NO INSTRUMENT LIGHTS IN AIRCRAFT. OWNER NOTICED NO LIGHTS AND NOTIFIED TECHNICIAN. TROUBLESHOOTING THE SYSTEM TECH FOUND THAT WIRES ON TOP OF RING WAS TOUCHING ONE ANOTHER, CAUSING A DIRECT SHORT.