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Yusynth Sample and Hold
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Yusynth Sample and Hold
memorygardens
I am currently having problems with my sample and hold build. The led is constantly on and doesnt change with the lfo or adsr i have plugged into it. the sample rate knob does nothing. the slew changes it a bit. no noise from any of the noise outputs. I know i can switch of trannies for that.... but I should have a least something. any suggestions?
stevebryson
memorygardens wrote:
I am currently having problems with my sample and hold build. The led is constantly on and doesnt change with the lfo or adsr i have plugged into it. the sample rate knob does nothing. the slew changes it a bit. no noise from any of the noise outputs. I know i can switch of trannies for that.... but I should have a least something. any suggestions?


Do you mean the complete S&H? I built one of these and the only problem I recall is a bad cap. This just caused the noise to be too quiet, nothing like the many problems you're describing.

Have you looked for a ground or power short? Have you checked continuity between +Vsh and all the places in the schematic it says should be connected with it (same for -Vsh, +Vn, -Vn)? I'd first check that without power, then with power very carefully check one of the points to make sure there actually is voltage there. Of course you should visually check for solder bridges under the PCB. Without more details I don't know what else could cause that many problems.

It's a great module and well worth getting it right.
Troubleshooter
I made the S+H/noise without big issues. So it must be possible.
There was a little problem with the "random" output I remember.
Just followed the Yusynth doc's no adjustments needed.
I have both S+H and noise on seperate small PCB's.

I could provide you with pictures if you don't find your bugs.
Very strange none of both circuits work... they function completely seperate.

I have the experience that most bugs can be found with a good visual inspection.

Youre Lucky it is a small PCB with only a few components. Also check the wiring ,grounding, and shorts on the frontpanel connectors.
Flareless
Did you ever resolve the issue with the rate?

I've just built two of these boards (the latest SynthCube revision) and they work perfectly except for the internal rate. I can use an external clock and everything works fine (slew, noise, etc) and I can use an external noise source without a problem.

The only issue is that when set to "Internal" the LED remains solid and can't be controlled with the potentiometer.
roglok
Flareless wrote:
Did you ever resolve the issue with the rate?

I've just built two of these boards (the latest SynthCube revision) and they work perfectly except for the internal rate. I can use an external clock and everything works fine (slew, noise, etc) and I can use an external noise source without a problem.

The only issue is that when set to "Internal" the LED remains solid and can't be controlled with the potentiometer.


hmm. it could of course be the PCB that's faulty. but depending on your panel design you could build the venerable two opamp lfo (integrator/comparator) on a piece of stripboard (or even rewire on the existing PCB) and end up with the same parts count plus a bonus triangle output.


schematic courtesy of guest/openmusiclabs
Flareless
The panel I'm using is the RE:Synthesis layout. The board is from SynthCube and is labeled "Sample - Hold - 2006" on the back but there's not other version number. This board does not require jumpers as traces are in place at the jumper holes.

I don't want to blame the board so fast, although there is a company making Yusynth boards where many have PCB flaws.

I'm going to double-check my parts in the section of the board controlling the internal timing. It's got to be something simple and stupid.

When clocked externally, though, this is a great module!
roglok
can you rule out a wiring error around the internal/external switch?
do you have a scope so you can monitor the output of the clocking circuit around D1? are you using a single opamp (TL071) or did you maybe accidentally place a dual one (TL072)? double check the cap and resistor values around U1.

if everything else works, this shouldn't be hard to troubleshoot.
Flareless
I will check these items today Roglok. Thank you for the suggestions.

I'll post my findings.
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