LFO 2 no triangle or sine waves

RyBowk · Joined: Nov 25, 2018 Posts: 33 Location: England

Haha, never. I’ll only learn by perseverance

gabbagabi · Posted: Thu Nov 21, 2019 8:29 am Post subject:

nice new word: perseverance, dunno if i will remember it

i checked the soundtronics-site,
the pcb are looking the same like yves, they even use the original documentation

so can we assume that we can use tis as orientation?

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where did u placed the probe for the scope, when it was on DC?

RyBowk · Joined: Nov 25, 2018 Posts: 33 Location: England

Pin14 of ic 2

gabbagabi · Posted: Thu Nov 21, 2019 11:13 am Post subject:

ok,
there u should measure a signal that is going from -3,5V to 3,5V

the scope schoots saying that the signal is going from 0V to 7V

that means ether u did not used the ofset trimmers, or they dont work

connect the scope again on pin 14 and try to play around with (both) offsettrimmers to test it

you also could try to measure on the middle pins of the trimmers, when you turn the trimmers u should be able to measure a voltage that goes from 0V to ~10V, on BOTH

RyBowk · Joined: Nov 25, 2018 Posts: 33 Location: England

So I’m getting 7.6volts from both trimmers

RyBowk · Joined: Nov 25, 2018 Posts: 33 Location: England

Measuring the power directly as it comes in pre 10ohm resistors is 12v, directly after the resistors I’m reading 11.83v. Please excuse my naivety but would this be normal?

blue hell · Posted: Thu Nov 21, 2019 5:16 pm Post subject:

12 - 11.83 = 0.17 or 170 mV.. over 10 Ohms and that would mean 17 mA of power consumption .. nothing unusual I think?

RyBowk · Joined: Nov 25, 2018 Posts: 33 Location: England

Thanks for clearing that up mate. I feel like I’m learning more everyday with you guys

gabbagabi · Posted: Fri Nov 22, 2019 7:15 am Post subject:

so u have measured 7,6V on both middle pins on the symetry trimmers?

then have turned the trimmers up and down and nothing changed?

u also measured at pin14, turned the trimmers up and down, and the SAW-Wave did not changed position in relation to the 0V Line on your scope?

what do u measure on the other (outer) pins?

RyBowk · Joined: Nov 25, 2018 Posts: 33 Location: England

Sorry I was tired yesterday,
They both measure from 0 - 7.6 when turned.
But neither affect the rising ramp from pin 14
I’ll take some more measurements when I’m home. Thanks Ryan

gabbagabi · Posted: Fri Nov 22, 2019 1:41 pm Post subject:

no problem,

can u measure if this variable voltage is comming tru to R15? u have to use the end which is not connectet to pin2/ic2

try both trimmers and since there is the range switch inbetween, use both switch positions

r15.png

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