Marantz Model 1050 Crackling Sound

[MAD]

Hi all, when i turned on my amp and put some audio source from any of the inputs (playing a song or video) after 2 minutes of being normally the audio starts to sounding annoying like crackling, this happens without doing anything like move the volume control, or switches, etc. Ive got the service manual of the Marantz model 1050 to check the circuit but i would like to confirm if this symptom is caused maybe by any filter or resistance or any transistor in preamp stage instead of power output transistors (2SD716 - 2SB686).

Link to the service manual:
http://akdatabase.org/AKview/albums/userpics/10007/Marantz%201072%20and%201050%20Service%20Manual.pdf

Any help is appreciated, thanks!

[AdamG]

Generally, any issues a few minutes after a unit is turned in means bad capacitors. As they heat up they can start to fail, but operate normally when first starting up. It's a pain in the ass to diagnose which one it would be, which means they all need to be replaced.

[Sir Thrift-a-Lot]

Unless you can see one or more that are obviously swelling or leaky.   Although replacing all of them is certainly a good idea, if the unit is fully functional otherwise.