no Res on smr4 v1 board
  • hello

    after a short into the main line of current ,ly shruti first generation with smr4 board ,have somes issues

    first the screen are frozen ,now it’s fixed with the help of forum user and the mains shematics ,thank you !

    but now i see an other problems on the filter the resonance doesn’t work correctly .
    i have searched the schematics but i not found ,i have found only the “checking sound on filter board”

    Do you have any schematics for search where this issue begin ?

    or do you have an idea of this problem ?

    thank you so much for your help

  • Post a photo of your board, we’ll see if you have swapped resistor values…

  • ok thank you

    component side:
    http://www.flickr.com/photos/69546228@N05/7308106408/

    solder side:
    http://www.flickr.com/photos/69546228@N05/7308104018/in/photostream/

  • Things to check:

    • Put the pole selector to 4 pole, since resonance is more emphasized in 4-pole mode.
    • Have you adjusted the resonance trimmer? Is it correctly soldered?
    • Voltage on the Q pin of the control board should go from 0V to 5V as you increase resonance. Is that the case?
    • There should be an audio signal corresponding to increasingly filtered versions of the oscillators signal on pins 14, 1, 7, and 8 of the TL074. Is that the case?
    • The signal at pin 7 of IC4 should be silence when resonance is set to 0, and its level should increase as you increase resonance. This signal should be affected by cutoff. If it is not the case, the very first thing to check is the following: if you remove IC5, and connect a 10k resistor between pin1 of the IC socket and -5V ; which voltage do you read on pin1 as you sweep resonance from 0 to 5V?
  • Put the pole selector to 4 pole, since resonance is more emphasized in 4-pole mode. ok i have tested ,in two position

    Have you adjusted the resonance trimmer? Is it correctly soldered?
    i think i have a problem with us ,no click at the end when turn clockwise ,

    do you think i can test it on the board ,what value i can read normally ?

    i check the voltage of Q

    result
    reso 0 = 0.12 mv
    reso 63 = 4.91 v

    i continue to check the other way

  • You cannot check resistances in circuit.

    It takes 22 turns to reach the end of the trimmer. When it reaches the end, it emits a faint click and is slightly more difficult to turn. Try temporarily shorting the 2 extreme pins of the trimmer. Does it improve resonance?

  • There should be an audio signal corresponding to increasingly filtered versions of the oscillators signal on pins 14, 1, 7, and 8 of the TL074. Is that the case?
    i hear signal on each pin

    The signal at pin 7 of IC4 should be silence when resonance is set to 0, and its level should increase as you increase resonance. This signal should be affected by cutoff.

    yes the signal increse and decrease if i turn cut and res pot

    but i have tested remove ic5 and connect 10k on pin 1 and -5v

    result :

    res 0 = 5.02v
    res 63 = 3.56v

    that’s correct for the lm13700 ?

    thank you sir

  • fixed the problem it’s on the lm13700 i have changed them and no working

    yahhhhhhhhhhhhhhhhhhhhhhhh