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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.
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
I’d look after these as well.
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.
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
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.
ok these are my results :
SW2
off
pin 1: 9,03v
pin 2: 0
pin 3: between 7 and 8von
pin 1: 0
pin 2: 2,74v
pin 3: between 7 and 8vI 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: 4,42vIC 2
pin 3: 4,74v
Pin 5: between 3 and 5v
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.
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?
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.
Ok i will try this! what exactly do I re-soldering ? The optocoupler ? R17 ? The ICs ? All cables ?
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.
Ok, I re-soldered the whole pcb.
I have checked all the components. Everything is OK.
but still no sound 🙁 . I start to despair
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.
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. 🙂
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.
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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