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Hum in the speakers ..

Sergey Green

Sergey Green

Active Member
Hi again,
Re. 2285B, it is very nice unit (after I cleaned it a bit) till I plug in the CD player. The instant I connect that RCA cable to the auxiliary 1, or pretty much any rca port, I get the hum in the speakers, even when the volume is all the way down. I tried different outlets, made no difference. Tried other cables, made no difference. Tried other cd player, made no difference. Plugged in the portable player, also through rca, everything is fine (only the music in the speakers). The instant I plug in the rca with cd player on the other end I hear hum. It is audible on every function; FM, phono, auxiliary, .. When rca is NOT connected to the player, FM works nice. Another thing, it comes loud at volume 0, then goes down at about 20% of the volume knob, and then goes rather aggressively with the volume button up again.

What possibly could that be?

The transformer is silent throughout. Actually very quiet unit otherwise.

thank you in advance,
-s
 
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It sounds like some type of ground loop. Can you plug the CD player's power cord into the back of the 2285B switched or unswitched outlet? Also, try another RCA cable? Someone more knowledgeable will have better advice...
 
Tried with the units plugged into the same output, with different cables, and different players. Same result. The same hum is heard throughout, even in FM. It goes away (completely quiet) when the player is unplugged from the rca cable. FM plays nicely.

-s
 
One other thing is to open up the case to see if the ground to the RCA jacks are soldered tight and flows to ground. With the receiver unplugged , check the resistance (ohm setting on your multimeter) from RCA Jack (negative jacket) to chassis.
 
slowpat said:
One other thing is to open up the case to see if the ground to the RCA jacks are soldered tight and flows to ground. With the receiver unplugged , check the resistance (ohm setting on your multimeter) from RCA Jack (negative jacket) to chassis.
Click to expand...
What should that resistance be?
 
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