Pioneer SX-7730 one channel causing woofer to move back and forth?

[savv]

I was listening to some vinyl with my Euro Pioneer SX-7730 hooked up to
AR 7 speakers when suddenly the left speaker started to lose music and the woofer shook back and forth. I also noticed that at certain times when i power on apart from the first click, it would be followed by another click after 3 seconds.

To isolate the problem, i switched the speakers and the same result happens which leads me to believe the problem lies with the SX-7730.

Any ideas on how to troubleshoot the problem?

 

[ukfan4sure!]

The first thing to check would be the DC offset and Bias Voltage in that channel.

Find a good copy of the service manual and it'll walk you through it.

 

[mayidunk]

Sounds like some kind of low frequency oscillation in that channel.

 

[savv]

The first thing to check would be the DC offset and Bias Voltage in that channel.

Find a good copy of the service manual and it'll walk you through it.

 

[larryderouin]

THE SERVICE MANUAL IS WRONG!!!!!!! On another thread for a SX-737 (which the 7730 is the Black face version of), it was determined that the manual was backwards on which pot to work, and when. I'll post up my updated S/M page with notes.

MARK THE FIXER and ECHOWARS verified this in the thread. I've also verified it on my 737. I'll see if I can dig up the thread again

Larry

Found the thread (link in next post). Here's the particular quote from Mark the Fixer......

note: the DC neutral voltage and idle current procedure in the service manual incorrectly identifies adjusting VR1 (pin 3 voltage to ground) and VR2 (pin 17 voltage to ground) for 0v and VR3 (voltage between pins 2 & 1) and VR4 (voltage between pins 18 & 19) for 20 millivolts. It correctly identifies the VR1, VR2, VR3 & VR4 positions in the drawing.

the CORRECT DC neutral voltage and idle current procedure is to adjust VR3 (pin 3 voltage to ground) and VR4 (pin 17 voltage to ground) for 0v and VR1 (voltage between pins 2 & 1) and VR2 (voltage between pins 18 & 19) for 20 millivolts.

 

[larryderouin]

The particular post in the thread is here.
http://www.audiokarma.org/forums/showpost.php?p=2408561&postcount=42
And the WHOLE THREAD.
http://www.audiokarma.org/forums/showthread.php?t=199020

I'm surprised that there aren't more SX-737 threads. Must be less prone to breakdowns.

Larry