Ok, sorry, i should have misconfigured my oscilloscope software...
Here is the signal on R62:
LEG 1:
LEG 2:
Sounds strange ?
Built Xoxbox // NO SOUND
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- mmm
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Re: Built Xoxbox // NO SOUND
Something's wrong here - but I'm not sure if this is a measuring issue.
One side looks pretty good (although the signal should be significantly stronger - about 5V peak-to-peak - but this could have something to do with the soundcard scope).
However the signal on the other side should be much, much weaker (about 150mV max) and will also look very different.
The side towards the oscillator should be the "strong" side and the side towards the filter the "weak" side.
What type of oscilloscope are you using?
You may also want to measure the resistance across R62.
One side looks pretty good (although the signal should be significantly stronger - about 5V peak-to-peak - but this could have something to do with the soundcard scope).
However the signal on the other side should be much, much weaker (about 150mV max) and will also look very different.
The side towards the oscillator should be the "strong" side and the side towards the filter the "weak" side.
What type of oscilloscope are you using?
You may also want to measure the resistance across R62.
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Re: Built Xoxbox // NO SOUND
Thanks for the answer MMM !
So it sounds that the VCF block is not working as it should (?).
I'm currently using my Mac book Pro built in soundcard as an oscillo with a software called "Signal Scope Pro", but i'm planning to buy a true oscillo to make the debugging easier.
I'll also change R62 to see if it change anything.
I'll let you know.
So it sounds that the VCF block is not working as it should (?).
I'm currently using my Mac book Pro built in soundcard as an oscillo with a software called "Signal Scope Pro", but i'm planning to buy a true oscillo to make the debugging easier.
I'll also change R62 to see if it change anything.
I'll let you know.
- mmm
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Re: Built Xoxbox // NO SOUND
That's hard to say since the signal seems not to make it into the filter. I'll think about it a little more. The voltages for the actual filter ladder looked ok to me.sequentialmood wrote:Thanks for the answer MMM !
So it sounds that the VCF block is not working as it should (?).
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Re: Built Xoxbox // NO SOUND
Hello,
I've changed R62, here are my new tests on the VCF.
leg 1 on R62 (VCO side):
leg 2 on R62:
on the res pot, when a key is pressed on keyboard:
With res at Zero:
With res at max:
but still no sound...
I've changed R62, here are my new tests on the VCF.
leg 1 on R62 (VCO side):
leg 2 on R62:
on the res pot, when a key is pressed on keyboard:
With res at Zero:
With res at max:
but still no sound...
- mmm
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Re: Built Xoxbox // NO SOUND
That's more like it. So the signal makes it through the filter - good!
Check at the "-" side of C38. You should get a signal there when pressing note buttons (in keyboard mode).
Check at the "-" side of C38. You should get a signal there when pressing note buttons (in keyboard mode).
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Re: Built Xoxbox // NO SOUND
Ok.
here is what i get on C38, when i press a key.
Many thanks, MMM!
here is what i get on C38, when i press a key.
Many thanks, MMM!
- mmm
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- Joined: Tue Apr 24, 2012 1:51 am
Re: Built Xoxbox // NO SOUND
OK, so there's essentially nothing.
Check with the oscilloscope on pin1 and pin2 of IC15B; you should have a very weak signal there (without having to press note buttons)
Check with the multimeter at R146 what happens when playing notes. Check similarly at D34 and D35.
Check with the oscilloscope on pin1 and pin2 of IC15B; you should have a very weak signal there (without having to press note buttons)
Check with the multimeter at R146 what happens when playing notes. Check similarly at D34 and D35.
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Re: Built Xoxbox // NO SOUND
Hi,
on IC15B:
on Pin 1, when i do not press anything. the signal reacts to Cutoff/Res/Env Mod values changes.
on pin 2, i do not have any signal.
When a key is pressed:
on R146 (leg1/leg2): 0.64V / 4.94V
on both D35 and D34: 11.75V
on IC15B:
on Pin 1, when i do not press anything. the signal reacts to Cutoff/Res/Env Mod values changes.
on pin 2, i do not have any signal.
When a key is pressed:
on R146 (leg1/leg2): 0.64V / 4.94V
on both D35 and D34: 11.75V
- mmm
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Re: Built Xoxbox // NO SOUND
We're getting closer.
Please measure with a multimeter the DC offset at IC15B:
pin 1, pin 2, pin 6, pin 8
Please measure what happens at IC15B pin 4 when playing a note.
Please measure with a multimeter the DC offset at IC15B:
pin 1, pin 2, pin 6, pin 8
Please measure what happens at IC15B pin 4 when playing a note.
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Re: Built Xoxbox // NO SOUND
here are voltages on IC15B:
seems good on pin 1, 2 => 5.33V
pin 6 => 5.33V
pin 8 => 5.38V
pin4 => 8 mV (i guess near null signal, even if i press a note on the keyboard.)
seems good on pin 1, 2 => 5.33V
pin 6 => 5.33V
pin 8 => 5.38V
pin4 => 8 mV (i guess near null signal, even if i press a note on the keyboard.)
Last edited by sequentialmood on Sun Apr 28, 2013 4:05 pm, edited 1 time in total.
- mmm
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Re: Built Xoxbox // NO SOUND
The plot thickens.
Theory: The volume envelope is missing or doesn't make it to the VCA (IC15B).
Please measure with the multimeter the behaviour when playing a note at the cathode of D27.
Theory: The volume envelope is missing or doesn't make it to the VCA (IC15B).
Please measure with the multimeter the behaviour when playing a note at the cathode of D27.
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Re: Built Xoxbox // NO SOUND
nothing on D27 cathode when a note is pressed.
- mmm
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Re: Built Xoxbox // NO SOUND
...which means no volume envelope.
Please measure both sides of D36 when playing a note. Since we are dealing here with rapidly changing voltages you'll possibly not get much information from the multimeter; it could appear as a small positive "dip" at the anode and a longer one at the cathode. You may also want to try to measure this with the oscilloscope.
Please measure both sides of D36 when playing a note. Since we are dealing here with rapidly changing voltages you'll possibly not get much information from the multimeter; it could appear as a small positive "dip" at the anode and a longer one at the cathode. You may also want to try to measure this with the oscilloscope.
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Re: Built Xoxbox // NO SOUND
ok, i've just resoldered few points on D27.
here are my results:
- on cathodes on D27 and D36, voltage raises when i press a key, the value depends on how i press the note button (0.2v/0.5V)
- now i've also got a raise on pin 4 of IC15B, which is around 11.8V (pretty high??)
Thanks.
here are my results:
- on cathodes on D27 and D36, voltage raises when i press a key, the value depends on how i press the note button (0.2v/0.5V)
- now i've also got a raise on pin 4 of IC15B, which is around 11.8V (pretty high??)
Thanks.
Please be positive and constructive with your questions and comments.