[undertowogt1]

Hi Fellow audio enthusiasts,

Thought I would post this question before contacting a local Yamaha repair service as I may be able to fix it myself. I am using my fathers vintage YAMAHA CR1020 receiver in "PREAMP BYPASS MODE".  I am just using the amp to drive some Magnapen SMGa speakers and using a different preamp.

The problem:

I turn the amp ON and everything is working great

Then about 1 min (pretty random time) later the right Channel drops in amplitude and and Freq. The bass is almost non existent and the woofer stops pumping. There is still sound coming out of the speaker, but at about 60% less volume

If I turn the amp OFF and ON the right channel will work again though this does not happen every time. It seems the amp needs some time OFF before the channel works again.

There are 3 Speaker outputs on the amp and this issues effect all 3 Speaker outputs on the right channel.

Any thoughts. I figured it would be an easy problem to diagnose for a person who is in the know.

[srb]

The Coupler switch on the back connects the Pre Out to the Main In when in the ON position.  In the OFF position there is no connection between them so that the Preamplifier and Power Amplifier sections can be used independently.  I'm assuming the switch is in the OFF position when you are referring to "Preamp Bypass Mode"?

If there was a switch problem I would think that it would more likely be when it is in the ON position.  Do you have the same channel problem when the receiver is in normal mode with the Coupler switch ON and a source connected to one of the CR-1020 inputs?

Steve

[undertowogt1]

Had some time to tinker with this now it is is working fine. It was acting up all week. I am going to have to wait it out enable the preamp when the issue arises again.

[undertowogt1]

The Coupler switch on the back connects the Pre Out to the Main In when in the ON position.  In the OFF position there is no connection between them so that the Preamplifier and Power Amplifier sections can be used independently.  I'm assuming the switch is in the OFF position when you are referring to "Preamp Bypass Mode"?

If there was a switch problem I would think that it would more likely be when it is in the ON position.  Do you have the same channel problem when the receiver is in normal mode with the Coupler switch ON and a source connected to one of the CR-1020 inputs?

Steve

Looks like The Couple switch. The problem happened again and I turned the Coupler switch ON and OFF and the problem was fixed. Maybe it just need some cleaning