Noise Ensemble - No Output

Started by HighSolstice, December 27, 2019, 12:57:28 AM

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HighSolstice

My Noise Ensemble build currently has no output.  It passes clean signal when bypassed but nothing when engaged.  I believe all parts are correct as well as correctly placed.  I've included my readings below.  How would I tell if I've got a bad PT2399?

PT2399:
Pin 1 - 4.98V
Pin 2 - 2.44V
Pin 3 - 0V
Pin 4 - 0V
Pin 5 - 4.98V
Pin 6 - 2.57V
Pin 7 - 1.65V
Pin 8 - 2.25V
Pin 9 - 1V fluctuating +/- .5V
Pin 10 - 3.2V fluctuating +/- .5V
Pin 11 - 2.42V
Pin 12 - 2.82V
Pin 13 - 2.48V
Pin 14 - 1.48V
Pin 15 - 3.36V
Pin 16 - 2.23V

7805:
I: 9.24V
G: 0V
O: 4.99V




anotherjim

Most of the PT2399 voltages look good.
Except...
Pin5 has the internal VCO clock squarewave. For DC volts, it ought to read the average voltage of a squarewave, which is half supply or about 2.5v. The reading you have suggests the VCO is not running. This can be due to internal lockup of the CMOS chip. If it has worked, then with no power on, try shorting all of the PT2399 pins out momentarily for about 10 seconds with a piece of metal foil. This might remove the static charge from the chip internals that is the usual cause of lockup.

Pin14 DC voltage should = pin15. A lower voltage on pin14 suggests a short into ground -  check your wiring to the volume pot.

HighSolstice

Looks like the PT2399 is giving proper voltages now after shorting the pins like you said.  I also took a razor to the edges of tracks 13-16 and it seems to be working now.  Thanks for your help!

HighSolstice

I added the loop mod with a 3.3M resistor and SPDT Switch between the input and output and it seems to work but has introduced considerable noise to the build.  Enough noise that I'm considering removing it altogether, is there any way I can reduce or eliminate the noise?

ElectricDruid

Quote from: HighSolstice on December 31, 2019, 04:37:52 AM
I added the loop mod with a 3.3M resistor and SPDT Switch between the input and output and it seems to work but has introduced considerable noise to the build.  Enough noise that I'm considering removing it altogether, is there any way I can reduce or eliminate the noise?

If you feed the output back into the input, you feed all the noise on the output back into the input too, where more noise is then added, and then it's fed back into the input again...etcetc. So it's pretty much *bound* to be noisy. This is the same reason it's hard to build a quiet flanger - the feedback.

The PT2399 tends to be cleaner at shorter delays, so they should be *less* noisy. Long settings are probably worse.

paul.creedy



Amusingly I built myself a Noise Ensemble yesterday which also didn't work  :o

I just remembered this thread and reset the PT2399 using a bit of kitchen foil - it worked :)

It's one of my Project Fuzz boards, which I thought I'd build and stick in an enclosure to test - no point having eight boards to debug in one go !

So one down, seven to go :)

HighSolstice

Glad this was helpful for you too Paul, gonna be boxing mine up soon as well.  In the end I decided to leave the feedback switch on my build.