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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