[MCC]

My McIntosh MAC 1500 receiver developed a small 60Hz hum yesterday and today I checked all of the power capacitors- they're OK (infinite resistance, capacitance as rated or higher). I have reason to suspect that the FM section of the receiver might be the culprit since it is the only section that I haven't overhauled. Since I don't use the FM on this receiver I've made the decision to remove its power by desoldering the RED/YEL wire from the transformer to the first 220Ω 5W resistor in the power section (circled). My reasoning is that I'll save both energy and the life of the tubes in that section and possibly fix the hum.

 

 

Service manual and full schematic: http://www.audio-circuit.dk/download.php?q=MAC1500_service_manual.pdf&cat=0

 

Now, I haven't yet taken any circuit design classes. Is this safe or will I start a fire?

 

Thanks!

 

Edit: I would also remove the filament supply power from that section.

Edit 2: I replaced the power cord with a modern grounded cord and the hum is gone. The question on if the FM section's power can safely be disconnected still stands for previously stated reasons.