[Marantz SR5012] Center channel keeps going into ASO/Overcurrent protection.

[acedogblast]

Re: [Marantz SR5012] Center channel keeps going into ASO/Overcurrent protection.

Disaster! The breaker for my room tripped and the "Magic Smoke" was released on the center channel. It happened when I turned the volume up. Worse yet both output driver transistors Q428 and Q434 now have shorts on collector to emitter but to base they are fine.

[acedogblast]

Re: [Marantz SR5012] Center channel keeps going into ASO/Overcurrent protection.

Emitter resistors for both Q428 and Q434 measure fine at 0.5 ohms.

[petehall347]

Re: [Marantz SR5012] Center channel keeps going into ASO/Overcurrent protection.

Disaster! The breaker for my room tripped and the "Magic Smoke" was released on the center channel. It happened when I turned the volume up. Worse yet both output driver transistors Q428 and Q434 now have shorts on collector to emitter but to base they are fine.

hope you wasn't running it with a load without output transistors .

[lotas]

Re: [Marantz SR5012] Center channel keeps going into ASO/Overcurrent protection.

Rather, you bought Q428 and Q434 - a fake. Now it's hard to find original transistors.

[petehall347]

Re: [Marantz SR5012] Center channel keeps going into ASO/Overcurrent protection.

these will be original
https://www.cricklewoodelectronics.com/2SB1647.html

[acedogblast]

Re: [Marantz SR5012] Center channel keeps going into ASO/Overcurrent protection.

All of the parts I have bough are from either Digi-key or Mouser. So I don't think that they are fake. Either way I have decided to give up repairing the center channel. I now plan to disable the center channel on the amp board and use external amplification for the center channel since this AV receiver has preouts. Thanks for all of your help.