# Pro-Ten/Blue _Blinking LED



## Kaiwa (Nov 14, 2021)

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?


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## JamieJ (Nov 14, 2021)

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


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## Kaiwa (Nov 14, 2021)

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.


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## Bricksnbeatles (Nov 14, 2021)

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


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## JamieJ (Nov 14, 2021)

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.


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## Kaiwa (Nov 18, 2021)

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.


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## music6000 (Nov 18, 2021)

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!


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## Kaiwa (Nov 26, 2021)

music6000 said:


> 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


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## PJS (Nov 27, 2021)

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.


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## carlinb17 (Nov 27, 2021)

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.


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## music6000 (Nov 27, 2021)

Kaiwa said:


> 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 .


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## carlinb17 (Nov 27, 2021)

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


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## Kaiwa (Nov 29, 2021)

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).


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## Kaiwa (Nov 29, 2021)

music6000 said:


> 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.


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## giovanni (Nov 29, 2021)

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...


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## fig (Nov 29, 2021)

You have IC1 & IC2 switched.


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## giovanni (Nov 29, 2021)

fig said:


> You have IC1 & IC2 switched.


Aren't they identical?


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## PJS (Nov 29, 2021)

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.


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## giovanni (Nov 29, 2021)

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


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## fig (Nov 29, 2021)




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## Kaiwa (Nov 14, 2021)

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?


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## PJS (Nov 29, 2021)

My bad, I was looking at the pro-ten green docs.  Oops.  Sorry.  Fig is right though - the should be the other way around


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## Kaiwa (Nov 30, 2021)

Oh what a shame 

The pedal works, somehow...
The volume knob works, but there's just on or off.
The same for tone, there's an a'area' from 9-12ish where it is quite bright, the rest is muddy and dark.


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## music6000 (Nov 30, 2021)

Kaiwa said:


> Oh what a shame
> 
> The pedal works, somehow...
> The volume knob works, but there's just on or off.
> The same for tone, there's an a'area' from 9-12ish where it is quite bright, the rest is muddy and dark.



When you replaced the Op Amps, You swapped the order?????
Check your Op Amps!
*fig* has pointed this out above!
This is what it should be :


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## Kaiwa (Nov 30, 2021)

music6000 said:


> When you replaced the Op Amps, You swapped the order?????
> Check your Op Amps!
> *fig* has pointed this out above!
> This is what it should be :
> View attachment 19326


Yes exactly! 

I changed the order the way you show and have now those weird problems with the volume an treble pots as described. Drive works fine. 

Any idea what could cause a volume knob behave like this: there’s either no volume, or volume but no increasing of the signal while turning the knob?


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## giovanni (Nov 30, 2021)

Uhm the volume knob issue may be caused by a short somewhere or maybe the pot is busted. Hard to say. I don’t have time to look at the schematic right now, but it you know how to read it, I would check continuity to start, then move on to an audio probe.


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## fig (Nov 30, 2021)

PJS said:


> Fig is right though


Again? That makes.........okay once! 

The Vcc is on pin 8 of the TL072 and pin 7 of the TL071. When you applied power to them while incorrectly socketed, it _may_ have damaged one or both chips. With a makeshift audio probe (a piece of wire with one end connected to the pedal's OUT tip) you can check the IN+ and OUT+ pins of both chips with the pedal engaged and at least determine if signal is being passed and/or amplified.

That said, these other folks are much more knowledgable than I, so please take my thoughts with a jigger of salt.


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## Kaiwa (Dec 1, 2021)

I replaced both chips when changing to correct position to be sure. I kept them, that's a good exercise to test them.  I'll try tonight.

Concerning the pots, I think I have to research how to test them, never done this before.


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## ADAOCE (Dec 1, 2021)

I made the same mistake using two TL072s! Tripped me up til I looked at the doc


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