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PostPosted: Tue Aug 11, 2015 1:05 pm 
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Hey guys,

This is my first build and I just finished, plugged in my One Spot and can get the led to light up momentarily and the bypass to work but besides that there is effect. After reading some posts it seems you need to keep the op amp and transistors cool and only solder one wire at a time. I think this might be the problem, however since its my first build I think it could be anything! I was trying to make sure i was avoiding cold joints, but i think i may have a couple.

Pictures of the PCB and pedal wiring are in the following link. https://imgur.com/nm38vG9,98dGs4Z,TT4aILC,a56n6Cw

And the bypass does work. The LED lights up when I hit the foot switch, but no sound comes out. Also no effect when i adjust the trimpot.

How do you test the transistors and IC? I have a multimeter to use aswell.

Thanks for any help, was really looking forward to this pedal, hopefully its a quick fix.


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PostPosted: Tue Aug 11, 2015 1:58 pm 
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Hi adevilbetweenus -

Without out a doubt, the first thing you should do is to clean up the soldering. This is your first pedal, so it is not surprising that you would have an issue with this. The fact is, I have done *A LOT* of soldering and I will sometimes goof it up :) so don't feel too bad. Read Stephen's Tips: http://byocelectronics.com/board/viewtopic.php?f=9&t=6401 that will help. Also, make sure you trim all those pokey wires - they are a short risk. Trim them to the top of the solder joint.

Let's start with that and see where that gets us.

Mike


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PostPosted: Tue Aug 11, 2015 2:07 pm 
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Well, if you get bypass and the LED lights up, we know that your I/O and DC jack wiring is OK, as well as most of the footswitch wiring, so that's all to the good. I haven't gone through and confirmed the resistor values by the band codes, but a mistake there is unlikely to render the pedal completely mute. All of that, plus the fact that you're a pedal building novice, would point pretty strongly to solder joint quality problems.

I would recommend that you start by systematically going through the PCB and re-flowing ALL of the solder joints, which only takes maybe a half-hour or so to work through. Add a bit of fresh solder to any joints that look "thin"--a good joint should be shiny and conical in shape, and cover the entire solder pad such that the shape of the eyelet hole underneath cannot be seen through the joint. Pay particular attention to any joints that are rough, dull, domed, or irregular in shape. I'd also recommend clipping any protruding component leads or wire ends down to the top of its solder joint, as these can sometimes be the source of shorts.

Try that first, and if it doesn't work, post back and we'll take it from there.

* EDIT *

Looks like Mike & I are coming from the same place on this.

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PostPosted: Tue Aug 11, 2015 2:11 pm 
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:) @DVM - great minds and all that!


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PostPosted: Tue Aug 11, 2015 6:00 pm 
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Thanks for the tips! I will be trying these tomorrow morning and see if it gets me anywhere.

Would there be any possibility that any of the components could be fried? After reading around, I'm now worried that i may have gotten my transistors or chips too hot.


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PostPosted: Wed Aug 12, 2015 7:38 am 
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adevilbetweenus wrote:
Would there be any possibility that any of the components could be fried? After reading around, I'm now worried that i may have gotten my transistors or chips too hot.

There's always a possibility of that, but it's quite rare. It generally takes a pretty extreme amount of heat to damage these components. Germanium diodes tend to be the most sensitive, but there aren't any of those in the Lazy Sprocket.

Follow the advice that Mike & I gave you above and see where that gets you....

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My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2


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PostPosted: Wed Aug 12, 2015 1:38 pm 
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Heres an update guys. I checked every resistor color code and they are all in the right place, as well as every other component on the board. I went slow to make sure I was being thorough to catch any silly mistakes. I also switched the wires for the Potentiometers to the other side of the PCB, and then touched up almost every solder joint on the bottom of the PCB. There were a couple that seemed like I didn't cover the entire contact pad, so I think that helped my cause a little bit. However, I'm still at the same place. Bypass working, but no effect or sound when i hit the footswitch. I included more pictures this time and closeups of the inputs and power supplies.

https://imgur.com/a/AH5hv

Is there anything that is clearly wrong? My next step I'm thinking would be to take out the MM and test components and joints to see which ones work and don't. Is that the next logical step?

I was kinda hoping I could get this pedal working first try, but at least its good trouble shooting practice for the future!

Once again, thanks for all your help and advice. Really appreciate how welcoming you guys are.

:~)


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PostPosted: Wed Aug 12, 2015 2:26 pm 
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Couple of questions:

  1. I see that the trimpot is dialed way over to one side. Have you adjusted it carefully across its full range?
  2. The top of the electrolytic cap at C3 looks damaged. Are you sure that cap is OK?

As far as testing with a multimeter, a good place to start would be the DC voltages on each of the op amp pins.

Image

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PostPosted: Wed Aug 12, 2015 7:00 pm 
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Regarding the trimpot, every time I tray to test to see if it works, i slowly dial it across its whole range.

Is the obvious sign that a component would be broken is that there would be no flow or reading of current across?

I didn't notice that cap before. I'll test that along with the op amp too and report back.

Thanks voodooman


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PostPosted: Wed Aug 12, 2015 8:21 pm 
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adevilbetweenus wrote:
Is the obvious sign that a component would be broken is that there would be no flow or reading of current across?

Current is a very difficult thing to measure in an effect circuit, so we concentrate on voltage, resistance, and continuity measurements.

Let's see what those op amp pin voltages look like and we'll go from there.

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My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2


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PostPosted: Thu Aug 13, 2015 12:34 pm 
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Just to review how to use a meter to test voltage:

* put your meter in DC Voltage mode
* some meters have a scale: you want to set it to measure voltages between 0v and say 20v or thereabouts
* put the black lead in one of the holes for screwing the back plate on
* make sure the pedal is powered and a cable is plugged into the input
* touch the red probe to each of the legs of the chip
* write down the results and report back!

Mike


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PostPosted: Mon Aug 17, 2015 10:06 am 
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Okay i measured the Op Amp chip. I didn't know exactly which pin number was which so I used the layout from this pic to guide me. http://www.swarthmore.edu/NatSci/echeev ... L2_411.gif

Here are the voltages i got from my DMM:

Pin Voltage
1 0.01
2 4.35
3 3.83
4 0
5 0.01
6 4.75
7 9.14
8 0

It was plugged into my onespot 9v powersource.


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PostPosted: Mon Aug 17, 2015 1:07 pm 
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Those look right. Try checking the voltages on each of the legs of the 6 transistors.

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PostPosted: Tue Aug 18, 2015 10:21 am 
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Something new that I noticed while I was trying to measure voltages was that when i had my guitar in the input, and the output directed to my amp, i couldnt get any voltage readings. But when I was messing around with some cords, I found out if i have the same cord in the input of the pedal, and then connect the other end to the output (so its the same cord running in/out of each 1/4" jack), I got voltage readings!

When I had the configuration set up, (guitar in, amp out) I could only get a voltage reading from the negative part of the AC jack, and nothing from the positive ends. I could see that this meant there was nothing flowing to the PCB, no mater what setting the footswitch was in.
But when I set it up with the input and output connected with the same cord, basically looping the signal into itself, I didnt get any reading from the negative part of the AC jack, but got a reading from the positive end which lead to the PCB and powered all the components.

I'm not sure what any of this means, but to sum it up I can only get voltage readings from the components when the input jack was looping to the output jack. Gave me some relief to find out I can get readings from the Op Amps and transistors but have no clue what it means that I can only get it in this configuration.

Any idea what this means?


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PostPosted: Tue Aug 18, 2015 12:33 pm 
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Sounds like maybe there's a power short somewhere in the pedal. When connected to your amp, there's a path to ground so you don't get a voltage reading. But if you loop a cable between the input and output, there's no real ground path and you can still detect voltage in the circuit.

Check all of your power and ground connections carefully. Look for any evidence of shorting between solder joints, particularly around electrolytic capacitor connections and wire connections on the PCB.

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My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2


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PostPosted: Tue Aug 18, 2015 12:36 pm 
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*EDIT* Or this ^ :)

My only guess is that you have a weak solder joint on the input jack such that the angle of the cable when you loop it makes a better connection...


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PostPosted: Tue Aug 18, 2015 2:05 pm 
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mmarsh and duhvoodooman thank you guys soooo much!!!

I finally got it to work! Wooooh!!! :D :o :o :o

It ended up being the stereo input jack that wasnt really making contact. I had an extra one from the confidence booster pack that came with my kit, so I switched it out and now it works!!

So happy right now thanks to you guys. This was my first build and it definitely wont be my last. Thanks again for helping trouble shoot everything, means a lot!!!


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PostPosted: Wed Aug 19, 2015 10:25 am 
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Woot! Good job troubleshooting and sticking with it!


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