Does anyone have spare panels/pcbs from this project still?
I still have some of my original PCBs, if you want that version and are in the US.
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Sounds good. I am in the US. Are there caveats I should know about in regards to the original board?
UmmmâŠI need to look through this thread to remember. I think I fixed everything on the Turing Machine, but maybe have a missing ground on one of the expanders.
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Thanks for this calibration setup insight.
It got me squared away as well.
Could you add this to your Readme.md or build notes?
or did I miss that?
Also per your LED advice, before I built I created a little breadboard experiment to find my âhappy placeâ with the LEDs I have in stock and determined resistor values for brightness and current.
Very helpful.
I have to resist the urge to redo every freaking LED in all my older builds now. HA!
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I canât get my Turing machine main board to work (A0 version), and would appreciate some advice.
Bits light up when powered on but do not change. Write switch does nothing.
Clock in works -tried various sources
Noise works, and trimmer adjusts gain of noise well
Pulse is not doing anything
Audio passes through when unplugged and scale attenuates volume, but when power is plugged in I get no audio.
primary 4015 gets warm.
Reflowed twice, probed around for shorts, and replaced all ICâs and 2N3904 with new from Digikey.
?? There are no audio inputs or outputs.
Sounds like either bits arenât being presented to the shift registers or clock isnât getting to the shift registers. If you have a scope look at pin 9 on SHIFTREG_MAIN1 and see if the clock pulse is there. If it is check pin 7 and see if both high and low pulses are appearing there. If you donât have a scope itâll be harder but you can check continuity from pin 9 to D1 and from pin 7 back to R13 to SWITCH_IC1 pins 2 and 10 et cetera.
I had issues with external clocks from an SQ64, but not my SQ1, and saw similar behavior with weak clock pulses. Another easy way to test clock input is take any of the 1222 outputs (or other VCO), you should see the lights begin to flicker, and if you unplug it you should have a random set of 8 bits. Worth trying quickly if you donât have a scope.
OUT into a mixer would produce a sound during calibration correct?
I did check for continuity from pin 9 and 1 to D1 and clock at the board connector. That was good.
I also found earlier that for C14 I had put a ceramic instead of film and replaced that
It looks like I have a clock pulse @ 9 but not at 7, but have continuity from pin 7 to R13
Much like a sequencer, Turing Machineâs primary out is CV, so donât expect any audible output in testing.
You should have high and low pulses at SHIFTREG_MAIN1 pin 7, but they arenât clock pulses, theyâre the bits being fed into the shift register. If you just have DC on pin 7 then the bits from the read/write toggle and the noise comparator arenât making it there.
This partâs complicated and confusing, but there should be high and low pulses produced at IC1 pin 7 and they should make it to SWITCH_IC1 pins 6 and 13. Exactly what happens then depends on whatâs in the shift register but there should be pulses getting to R13. If thereâs noise going into IC1 pin 5 but no pulses on pin 7, check the voltage on pin 6; it should not be bit or small (±10.5 V or whatever) but in between, and it should change when you adjust the front panel knob.
Well, I spent the last week troubleshooting this module. Tonight I re-did C14 again, and then re-flowed the Jacks board and replaced its 2 LED resistors with 150K and it is finally working!
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Is this supposed to just cycle like this forever regardless of what I do with the big knob? From what I can gather it seems to be acting as if itâs turned all the way to the right no matter what.
Itâs acting like the bit thatâs supposed to come from the noise source is always 0⊠I think. Something like that. Anyway, no, not supposed to do anything as dull as that. Do you get strong noise on the noise output jack? Pin 7 on IC1 should jump randomly between about +10.5 and -10.5 volts (need a scope to check that).Verify the pot wiper voltage ranges from about -10.3 to about 10.3 V and I think IC1 pin 6 should go about half that, so around -5 V to 5 V roughly.
The noise output is strong and I verified the pot wipes between 0-50k ohms. I can scope the pins if you think I need to still but itâs very loud at the jack
Canât be right, if youâre measuring between wiper and ground. Canât be more than 12 V. (I made a mistake above, corrected.)
Thatâs not wiper to ground, itâs wiper to +12 V.
Ok now I get
-9v to +7v