Elenos SF500 Watt FM Transmitter

Had a few of these transmitters in over the last couple of years. Elenos make some nice equipment. Well made and generally not to bad to work on and service.

This transmitter came in with a complaint that it would shut down intermittently with an error code stating that the final output stage was drawing too much current. Even with an output of around 100 watts, tripping happened sporadically. Scoping the 48V power rails, there was a massive ripple present. During inspection, we noticed “that smell” that nobody likes. Before the power switch could be reached, there was a loud pop, a puff of smoke and the pressure bung from one of the bulk capacitors shot passed my ear.

Removed all the capacitors and apart from the one that had blown up and gone short circuit, the others were found to have no capacitance at all., open circuit. How the power supply managed to provide any power at all is testament to it’s good design. 4 nice new computer grade capacitors fitted. 10,000 uF 63V 20,000 hour rated and high ripple current. All fitted and transmitter was up and working well. Power in vs power out was a good ratio, running cool. Station back on air.

Leave a Comment

Your email address will not be published.

Scroll to Top