I have legacy Whelen wingtip strobes that have LEDs added as the position lights. All of my strobes (back included) are not working. The power supply is the HDACF. It is under the floor in the baggage area. All the connections look good. When I turn on the strobes switch on the panel I can hear a little sizzle noise coming from the power supply. It is not loud but obvious. I haven't checked any of the other connections. I didn't think that noise was normal so now assume I have found the problem. Am I right or do I need to keep looking? If it is the power supply should I just switch it all out to LED? If so which LEDs? If not where do I check next? RV-9A with 1400 hrs. I have never had a problem with the lights until now. I am not the builder.