Home Forums GuitarPCB Build Support APOLLO TREMOLO NO SOUND OUT (SOLVED)

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  • #18793
    nitsuj
    Participant

    Hello ! I work on the Apollo Tremolo and I have a problem.

    No sound comes out when the pedal is engaged. the bypass work, the LEDs works, and the potentiometers flash the LEDs.

    I have between 7 and 8 volt on SW2.

     

    I read all the topics on the subject but I can’t find anything.

    #18795
    Billy
    Moderator

    Nitsuj

    Welcome to the forum

    We’d need to see a picture of your in and out jack wiring and DC jack wiring so we can trace where it goes to

    The white square in and out T for tip pads should go to the 3PDT pcb in and out lugs

     

     

    #18797
    fig
    Participant

    I’d look after these as well.

    #18798
    nitsuj
    Participant

    Hi !  thanks for your welcome.

    For me the connections between in and out jack wiring to 3PDT  are good. But may be not.
    here are the pictures :

     

    the yellow cable is ok the burn is only superficial. And the multi-weld does not present any defect.

    #18833
    nitsuj
    Participant

    Hello, I have build a audio probe with a breathboard.
    My video may give you some clues to solve my problem.

    https://www.youtube.com/watch?v=84XcLLYXna8

    thanks for your help

    #19017
    wilkie1
    Moderator

    If the rate LED is flashing and varies with the speed pot, then the LFO portion of the circuit is working.

    Check to see if you have a varying voltage on the one side of SW2.  That will be the signal going to the Optocoupler.  Make sure the Optocoupler coupler is mounted correctly with the dot oriented on the + side.

    Measure the voltage on pins 3 and 5 of the IC.  You should have about 4.5V or half of the supply voltage.

    Report your findings.

    #19023
    nitsuj
    Participant

    ok these are my results :

    SW2
    off
    pin 1: 9,03v
    pin 2: 0
    pin 3: between 7 and 8v

    on
    pin 1: 0
    pin 2: 2,74v
    pin 3: between 7 and 8v

    I mount the optocoupler as on the diagram the point on the negative terminal on the right (not on the + side)

    The voltage on pins 3 and 5 of IC 1 and 2

    IC 1
    pin 3: 4,74v
    Pin 5: 4,42v

    IC 2
    pin 3: 4,74v
    Pin 5: between 3 and 5v

    #19026
    wilkie1
    Moderator

    Your voltages are still not correct.

    Try trimming the loose ends of wires showing on the board and then re-soldering ALL connections on the board and on the pots.  (remove both ICs before doing this.)

    I think your LFO is working since you reported that the LED is flashing.  But I did not hear you report any varying voltage reading.

    After reinstalling the ICs, measure and report all voltages on the IC pins.  Note if any are VARYING.

    #19040
    nitsuj
    Participant

    what voltages are you talking about exactly?

    SW2 or IC. Because for me the voltage of the IC is good.

    You announced around 4.5v and I found 4.7. It’s pretty ready.

    I also think LFO is working. Variable tension where on the board?

    I don’t quite understand the maneuver. Do you want me to unblock all the cables and re-wire them? What interest?

    #19044
    wilkie1
    Moderator

    When SW2 is “OFF”, the voltage at lug 2 of the switch should be a steady voltage set by the BLEVEL trimmer.  When the switch is “ON”, the voltage should be changing at the speed of the LFO.  That voltage changes the brightness of the LED inside the optocoupler which then changes the resistance of the optocoupler and permits the signal to pass from pin 7 of IC1 to R17.

    By re-soldering we mean to slightly heat the solder connection until it softens and renews the connection.  This is a technique that helps to fix poor solder connections.

    #19045
    nitsuj
    Participant

    Ok i will try this! what exactly do I re-soldering ? The optocoupler ? R17 ? The ICs ? All cables ?

    #19046
    wilkie1
    Moderator

    Since we are not sure where you may have a poor connection, I suggest you re-solder ALL solder pads on the pcb board as well as connections to jacks and switches.

    #19059
    nitsuj
    Participant

    Ok, I re-soldered the whole pcb.

    I have checked all the components. Everything is OK.

    but still no sound 🙁 . I start to despair

    #19066
    wilkie1
    Moderator

    Take a new round of voltage measurements on all pins of both ICs as well as SW2 in both positions.  I am looking for verification that the LFO is working and that the varying voltage is reaching the optocoupler.

    Did you read the helpful guides on the website?  You may need to build an audio probe to trace the signal.  But first, I want to see if there is another issue that we may isolate before doing that.

    #19118
    nitsuj
    Participant

    Here are my measurements :

    DC measurement

    <span style=”text-decoration: underline;”>IC 1 : varying voltage</span>

    P1 : 2,60 to 6,03v up and down

    P2 : 2,60 to 6,02v up and down

    P3 :2,60 to 6v up and down

    P4 : 0v

    P5 : 8,40 to 6,06v up and down

    P6 : 2,40 to 6v up and down

    P7 : 1,03 to 8,30 up and down

    P8 : 9,02v

     

    <span style=”text-decoration: underline;”>IC 2 :</span>

    P1 : 4,49v

    P2 : 4,49v

    P3 : 4,48v

    P4 : 0v

    P5 : 4,47v

    P6 : 4,50v

    P7 : 4,53v

    P8 : 9,02v

     

    <span style=”text-decoration: underline;”>SW2 :</span>

    ON

    P1 : 0v

    P2 : 2,75

    P3 : 7.50v to 8,30v up down

    OFF

    P1 : 9,02v

    P2 : 0v

    P3 : 7.50v to 8,30v up down

     

    Yes I have read it several times !

    and I have already built an audio probe I have even shared a video a few posts above. 🙂

     

    #19124
    wilkie1
    Moderator

    SW2 should have the following voltages:

    ON P1: @ 9V (depending on the setting of the trimmer)

    P2: 7.50 to 8.30V

    P3: 7.50 to 8.30V

    OFF: P1 @ 9V

    P2: @ 9V

    P3: 7.50 to 8.30V

    Check the solder connections to and from SW2.  If they are good, you may have a faulty switch.

    #19125
    wilkie1
    Moderator

    Your ICs seem to be fine.  The LFO is working.  You are just not getting the varying voltage to pin 2 of SW2 and then on to the optocoupler.

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