Help !Marantz 2270 loud hum popping sound

[dinkylink]

Hello guys, thank you all for reading this , I have a Marantz 2270 that just came out of storage , it used to work beautiful but now as soon as you turn on the speaker relay disengages after a few seconds and get a loud hum popping noise for a second , relay kicks into protection disengages after a few seconds and I get the loud popping hum , Im sure its DC voltage
I have read many of your posts here (Thank you)
and so far I have done the following

1) removed the pre-out main in and used another line level source, same result
2) used headphones to test, same loud hum/pop
3) checked output transistors for shorts , none impedance between pins above 9K Ohms
4) Visually inspected the unit for any dark resistors fat capicitors but it all looks good.

any advice is truly appreciated and I hope I can bring this gentle giant back to life

Thanks in Advance

 

[AlphaEcho35]

When you first turn on, the relay is normally disengaged. It should engage after 2-3 seconds. From your description, it sounds like it is engaging properly and that is when you hear the the loud popping hum, right?

Have you measured DC on the speaker outputs?

https://www.audiokarma.org/forums/index.php?threads/amplifier-distortion-dc-offset-and-you.5634/

 

[dinkylink]

Thanks, I just checked it and I have 45.2 DC Volts on each channel, reading some older posts it points to the output transistors but these seem fine, again thank you for any advice

 

[mbz]

Carefully measure dc voltage (black probe connected to any black speaker post) at,
- J753
- J755
- J754
- J757
- J760
- J759
- J761

These are all on the power amp board (P750)
I assume you've diode tested the output transistors. Might be a problem with drivers.

 

[petago1975]

Hej everybody, same problem with a 2270 original suddenly popping noise in both speakers. The problem was in the power board P800. Capacitor C805 3.3uF was leacking. Changed and solved. Check or recap all them in PB400. Transistors seems ok (original ones), musical regards

 

[petago1975]

PS. About my last post, correction; When I wrote PB400 I meant P800! Lapsus calami.