Yamaha CS80

Hi David
To specify the problem, the suboscillator can be "heard" also at low frequency because of a strong noise component and, strangely, even without any modulation amount to anything; even stranger is the fact that this effect can be heard on R output only , while the L goes pretty steady about it.
The ringmodulator is a different story: the effect can be heard on both channels, loud enough to tell it's not natural, moreover , if you turn "modulation" at full you can hear a strong amount of background noise; I'm beginning to think it can be one of ringmod's 1452 pre-amps which has gone fishing.
Any suggestion about it? Thx for your reply...
M
  ----- Original Message ----- 
  From: David Rogoff 
  To: yamahacs80@yahoogroups.com 
  Sent: Tuesday, June 10, 2008 5:54 AM
  Subject: [yamahacs80] Re: problem: audible modulations at no playing.


  I just tried it with headphones and the volume cranked. It's definitely 
  there, but pretty low level. It's not surprising since the RM and the 
  output pre-amps are both on the PRA board. I noticed that the pre-amp 
  ICs already have RC coupling on their power supply pins. Maybe 
  calibrating the RM and pre-amp would help.

  I don't hear any Sub Oscillator bleeding to the outputs on the unit I have.

  David

  Laurie Curry wrote:
  > I believe I also hear some leakage from my RM circuit....
  > -----Original message-----
  > From: "Max Fazio" faxiomas@...
  > Date: Mon, 09 Jun 2008 02:47:54 -0600
  > To: yamahacs80@yahoogroups.com
  > Subject: [yamahacs80] problem: audible modulations at no playing.
  >
  > Hi, writing here for a friend's CS80.
  > My friend found a strange problem: when he does set the ringmod's
  > speed at full with modulation at full , the sound coming from the
  > modulator is quite hearable : the fact is that this sound you can hear
  > even without playing anything on the keyboard; same problem happens
  > with the SubOScillator: when he sets the speed at full, the sound can
  > be heard without any key pressed.
  > I believe there must be something wrong with some preamps in OE1 board
  > or PRA's muting FETs, my idea is to look at R51/52 to see if is there
  > any faulty resistor concerning the Suboscillator.
  >
  > Anyway I'm looking for your savvy advices.
  > Thx for anyreply.
  > 



   

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