Quick question about the VCA / BA6110

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ivo francx
 
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Quick question about the VCA / BA6110

Post by ivo francx »

Hey,

One quick question:
What's the voltage on pin4 of the BA6110 supposed to be?
I measure 0v. As soon as I trigger a note in the manual mode, the voltage ramps um to 11.7V for a short time. Then it slowly decreases until it reaches 0v again. Is this behaviour normal, or did I fry my BA6110?

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antto
 
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Re: Quick question about the VCA / BA6110

Post by antto »

that connects to Q1 and that's basically the Volume envelope there

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ivo francx
 
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Re: Quick question about the VCA / BA6110

Post by ivo francx »

So this particular behaviour is normal?

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antto
 
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Re: Quick question about the VCA / BA6110

Post by antto »

well, is there anything wrong with the sound/behaviour of your x0x?
if you're not sure - post a short audio recording

as far as i can tell from the schematic, pin4 is connected to Q1.. so that must be the volume envelope, which is a RC decay with a fixed decay time (about 5-ish seconds)

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mmm
 
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Re: Quick question about the VCA / BA6110

Post by mmm »

If I remember correctly a jump to the 12V voltage at pin 4 is indicating a problem with BA6110 (or its surrounding circuitry). With a working BA6110 the jump is around 1V or so. I'll have to verify this again, though.

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ivo francx
 
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Re: Quick question about the VCA / BA6110

Post by ivo francx »

thanks for the replies so far. My x0x is actually making no sound at all. If I use a jumper wire to connect the filter output on the resonance knob to pin 7 of the BA6110, I do get sound. So the rest of the x0x is working just fine. It's just the VCA that seems to be broken. My first guess was also that the BA6110 is broken, so I already ordered a new one. I just wanted to make shure that I won't fry the new BA6110 when I replace the old one with it...
But as far as I know I can't really fry the BA6110, unless I supply more than 15V to it or reverse the polarity, right?

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mmm
 
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Re: Quick question about the VCA / BA6110

Post by mmm »

If I remember correctly the BA6110 will pull the voltage down significantly (hence the much smaller change at pin 4 with a working BA6110). A large swing indicates that the BA6110 isn't working for some reason. (All this just from memory).

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ivo francx
 
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Re: Quick question about the VCA / BA6110

Post by ivo francx »

yup. It was the BA6110. I've replaced it and it seems to work now..
Thanks!

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