Pro-Ten/Blue _Blinking LED

[Kaiwa]

Hi,
Does anybody know what could cause this problem:
When the pedal is active the led is blinking (on/off in a regular tempo). When volume and tone are turned on max the 'blink' can be heard through the amplifier. The sound of the guitar does not come through.

Any ideas?

 

[JamieJ]

Are your ICs upside down? They have probably been damaged. The circle pin 1 should be at the top left

 

[Kaiwa]

Oh hey Jamie, yes that was right. Thanks a lot.

Now that I changed the ICs and inserted them the right way, the LED is always on, no matter how often I engage the footswitch. Still no sound.

 

[Bricksnbeatles]

Looks like at least one pin of the footswitch is shorting against the enclosure

 

[JamieJ]

This pedal is a modified blues breaker and has an extra OP amp. I’m not sure if that is being used as a buffer in this circuit. My first thought would be to replace the two op amps first to see if that changes anything. Do you have anymore TL072?

Have a good look at your switch connection. Check for any solder bridges - I can’t tell of that is a bridge on the picture.

It would also be helpful to see a picture of the solder side of the board.

 

[Kaiwa]

I replaced the ICs and inserted the right way, resoldered the power jack and input output jacks and isolated the LED better.

The ON/OFF works fine now, the LED is OFF on OFF and ON on ON.

But I can't still get out any signal out of it.

 

[music6000]

Are you plugging the Guitar lead into the Input Jack side of pedal, To Amp from the Output Jack.
This is a common mistake if the pedal is upside down!

 

[Kaiwa]

Are you plugging the Guitar lead into the Input Jack side of pedal, To Amp from the Output Jack.
This is a common mistake if the pedal is upside down!

Yes tried both to be sure Still no sound.

I currently have the same problem on two pedals. Sound gets trough, when footswitch engaged the LED is on but the sound is off

 

[PJS]

Some of your solder joints on the leads joining the pcb to the switch board look very dodgy. Reflow them and make sure the solder looks as if it making a nice fillet, rather than a sphere.

 

[carlinb17]

if your still working on this I would recommend starting to look at the footswitch. With two other pedals acting the same way it's not a coincidence. I would check your continuity throughout the switch lugs to see if you have a bridge under the breakout board. You also don't need a resistor for the led (you can have one there it will just make the led dimmer). The LED resistor is R102 I believe but without a schematic don't quote me.

 

[music6000]

Yes tried both to be sure Still no sound.

I currently have the same problem on two pedals. Sound gets trough, when footswitch engaged the LED is on but the sound is off

Check for Continuity!
You should have No continuity Left to Right on same row, next to each other .

 

[carlinb17]

you will have it on the bottom, the left and right are connected via the trace in the breakout board

 

[Kaiwa]

Hey guys thanks for your help!

I also suspected the footswitch at that point. With the multimeter I found that IN & GND were bridged on the pcb and breakout board and I could not solve it. So I decided to place a footswitch without breakout board. IN & GND aren't bridged anymore.
I also placed tape under the volume pot as the legs are bit longer than those of the other two pots and maybe touching, but I see 2 millimeters space at least to the enclosure.

Still no signal. Bypass still works...

But what I found playing with the pots was that it plopped when i turned the volume down completely. This was repeatable, always when I was turning volume down from a minimum to point zero (from 8 to 7 o'clock).

 

[Kaiwa]

Check for Continuity!
You should have No continuity Left to Right on same row, next to each other .

View attachment 19212

Yes that's Ok and works like on this schematic, left and right connected cause wired connection.

 

[giovanni]

Did you try reflowing the solder joints that look a bit dodgy? Also your component tits are a bit long - that wouldn't cause the issue but they are acting like tiny antennas picking up noise...

 

[fig]

You have IC1 & IC2 switched.

 

[giovanni]

You have IC1 & IC2 switched.

Aren't they identical?

 

[PJS]

TL071 is a single op amp. TL072 is dual. The pinouts are not the same. According to the build docs they should both be dual op amps, so the TL071 is just wrong.

 

[giovanni]

Oh I totally read 72 on both! Very good catch @fig and @PJS

 

[fig]