Please, help me with my project!

[asintoras]

 
Hi guys,

This is my first post here. I don't know how to read schematics and almost nothing about electronics, but I know how to solder and I have built some projects before: a power attenuator - Dr.Z Airbrake clone; a loop pedal; some A/B/Y switches, several pedalboards and so on. All of them work wonderful.

Then I decided to build a copy of my favorite and long gone pedal by C. Martin. I got the vero-layout here for the Plexi - Bone (replace the B with a T ) and started my project from there. I also have a 12V DC power supply where I can switch the polarity tip which I wanted to use for this project. The power supply works fine.

I followed all the steps from the vero-layout. The tracks were properly cut (I tested them with my multimeter) and the components seem to be OK.

One thing you will notice is that I ordered wrong values for the 330pf capacitor (I ordered 33pf), so I connected three 100pf in parallel in order to get the 330pf (well, 333pf). The LEDs are not connected yet to the switches, but first I wanted to see if the pedal is working. Also, that IC is not the final one ( I have the LF347N), but I wanted to test the pedal with that just in case I screwed it up, which seems to be the case...
The pedal does absolutely nothing: the guitar produces no sound even when I hit the switches. The clipping LEDs do not turn on. I tested the DC jack and it is receiving voltage (+ - 10V).

Do you see something wrong from the pictures?
Is incorrect to do what I did with the capacitors?
Is incorrect the way I connected the +VE and -VE?








Any idea or suggestions will be very welcome.

[Govmnt_Lacky]

If you look at this picture, the 3PDT switches are wired wrong.

The way you have the switches oriented in the picture, you need to use the rows in an up/down fashion. NOT Left/Right.

Have a look at this example:

http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_tb_dcjack.gif?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Follow the flow of the signals and you will be able to determine which poles to use.

P.S. In the future, use some DPDT or SPDT switches for projects like these. It will save you some money as they tend to be $1-2 cheaper/each 

[deadastronaut]

[quote ]




P.S. In the future, use some DPDT or SPDT switches for projects like these. It will save you some money as they tend to be $1-2 cheaper/each 

yep DPDT'S...if i were you i would pull those expensive switches out. and use them for another' 3 ' true bypass with led pedals (future projects)....and replace them with the DPDT (6 pole ones) ...
good luck!.

[asintoras]

OK... Reuben was very kind and send me some suggestions and pointed out a few errors:

The IC was installed up-side down.
There was a missing cable from the boost switch to the A18 on the board.
He thought that maybe I got a wrong resistor in R4. I installed another 47ohm resistor just in case.

The problem is that I burned my LF347N yesterday  I am waiting for the new one to arrive. I went to Radioshack (the only freaking electronic store in town) and only found a different Quad OP-amp (LM324N).
I also noticed that I had an additional track cut (F3) and I corrected that.

I tested it again with the LM324N but still doesn't work... I checked again the board with my multimeter to see if there is any other track wrongly cut or that is not making contact and everything seems to be OK... but it still doesn't work.

[asintoras]

If you look at this picture, the 3PDT switches are wired wrong.

The way you have the switches oriented in the picture, you need to use the rows in an up/down fashion. NOT Left/Right.

Have a look at this example:

http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_tb_dcjack.gif?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Follow the flow of the signals and you will be able to determine which poles to use.

P.S. In the future, use some DPDT or SPDT switches for projects like these. It will save you some money as they tend to be $1-2 cheaper/each 

Well, I got these switches around and I understood that 6 poles will never work when you want to use LEDs. Can I use DPDT and still activate LEDs? How should I wire them?
Also, according to the diagram you are showing the rows are left/right, not up/down... Are you sure I connected them wrong?

[asintoras]

OK...

Second round:
I changed the connection on the switches as suggested by Govmnt_Lacky and now I can get sounds out of it but with lot's of noise (it is out of the box now and I have a radio station just in front of my house).
However, the boost seems to work fine but not the Drive. When I press the Drive switch, a loud noise comes and is constant. The high-gain is only activated if the Drive is on, so of course I haven't tested it yet. 

Maybe is because of the wrong OP-amp?

Many thanks folks, and keep the suggestions coming. I hope to be able to make it work this weekend.

Best,

Francisco

[asintoras]

Other news:

I re-connected some cables and cleaned up a little bit everything.

Now it sounds, but horrible and with lots of noise... The drive activates now but some of the pots are working weird: the "Level", the "High gain" and the "Drive" get silent when you put them at max.
Jesus... this is a mess! I guess the pots in the diagram are shown as if you are looking from inside the pedal, right?

I will get there eventually. This has been an adventure for sure!

[Govmnt_Lacky]

I have two suggestions:

1) Check your wiring to the pots. You may have them wired backwards. That COULD be causing your "Level, High Gain, and Drive" problems.

2) From the pictures you have posted, it definitely looks like you have a ground loop going on (which could be causing A LOT of your noise). If you look at how you have your input and output jacks connected, you are actually forming a ground loop.

You need to remove ONE of the following wires:

The wire from the Board ground to the Input jack ground. OR
The wire from the Input jack ground to the Output jack ground. OR
The wire from the Output jack ground to the Board ground

You have ALL THREE installed and that is forming a ground loop!

Good Luck 

[asintoras]

Here is what I have now, but still not working...



(the back of the PCB looks a lot better in person... I don't know why it looks so messy and dirty in this picture).

I guess I tried everything:
-changed the switches, although I also tried with the 3PDT with exact results;
-eliminated the ground loop;
-changed cables for better quality cables;
-replaced that bunch of capacitors for proper 330pf units;
-changed the 47ohm resistor;
-changed the connection on some of the pots;
-connected missing cable from the boost switch...

The strange thing is that when I use the LM324N I can get sounds out of it, but horrible sounds... I have a video to show how it sounds:
http://www.youtube.com/watch?v=Rlu_vjAOTSU
The last switch I press is the boost, which seems to work OK. The sound even when bypassed is still distorted (the amp had a  very low volume, and obviously not distorted). The pots are still working a little weird, but better than before.

But when I switch to the LF347N I have no sound at all. The LEDs do blink when I play with the LF347N, but it does not blink when I use the LM324N.

My last hope is a local friend who built amplifiers, but it is very hard to find him... I live in a very small town in the middle of Texas (College Station), in case someone is from here.

[Govmnt_Lacky]

Looks like your AUDIO and TONE pots (P3/P4) are wired wrong  I see that they are the pots at 1 o'clock and 3 o'clock in this picture...

Comparing your pictures with the layout they are wired reversed. Take a look there.

Beyond that (I dont think that will solve your problem) you might want to get out the old DMM and check your board traces and look for cold solder joints.

Good Luck 

[asintoras]

Good observation, but I did that on purpose, since the pots were working backwards (at max, they were silent).
Did you listen to the video I posted? I can get sounds out of it with one of the IC chips, so I guess the solder joints are OK, but with the other IC chip I can't get any sound out of it, and I have 2 new of those units.

Please excuse my ignorance, but how do I check for cold solder joints?

[asintoras]

And what is the DMM??

[Govmnt_Lacky]

Good observation, but I did that on purpose, since the pots were working backwards (at max, they were silent).

Interesting. That does sound logical though.

Did you listen to the video I posted?

Sorry but I cannot check the video now because I am at work and do not have access to Youtube.

Please excuse my ignorance, but how do I check for cold solder joints?

The best way is to check the component connections by checking from component lead to component lead. Use your Multimeter to check for resistance on the COMPONENT SIDE. This way, you have to check THROUGH THE SOLDER JOINTS. If you check between two leads that should be connected and it does not show a connection, then you either have a bad trace OR a cold solder joint. Simply re-heat the joint with your solder iron.

Have you looked at and followed this thread yet?:

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Look at this thread and follow it EXACTLY. Then repost here and it will help get this fixed ASAP. 

[Govmnt_Lacky]

And what is the DMM??

DMM = Digital Multi Meter

This tool can be used to check Voltage, Resistance, Current, Continuity, etc. in a circuit.

Just go to Google and type in "Digital Multimeter"

[Govmnt_Lacky]

I also noticed that you tested the circuit initially (in your first pictures) with an LM339. That is a Quad Comparator chip.

Then, you installed an LF347N (Quad Op Amp) on the second attempt. 

What IC does the circuit call for? These two ICs ARE NOT THE SAME.

You definitely would not get ANY output from the circuit if you used one in place of the other.

[asintoras]

Yes... the LM339 was a mistake...
Now I am dealing just with the LM324N and the LF347N, which are both op-amps.

Thanks for your help. I will look through the link you suggested...

Have a good weekend.

[asintoras]

And what is the DMM??

DMM = Digital Multi Meter

This tool can be used to check Voltage, Resistance, Current, Continuity, etc. in a circuit.

Just go to Google and type in "Digital Multimeter"

Got it... many thanks.

I have a very cheap multimeter but it is analog... maybe it will be a good idea to get a decent digital DMM.
I really appreciate all your patience and help folks.

[asintoras]

I also noticed that you tested the circuit initially (in your first pictures) with an LM339. That is a Quad Comparator chip.

Then, you installed an LF347N (Quad Op Amp) on the second attempt. 

What IC does the circuit call for? These two ICs ARE NOT THE SAME.

You definitely would not get ANY output from the circuit if you used one in place of the other.

I am sorry for not replying this before... The circuit calls for a LF347N.
I bought the LM324N just to test it before my additional LF347N arrived.

[asintoras]

Updates: a friend of mine helped me with the pedal creating a board right from scratch, and he added another little board for the voltage thing to duplicate -6 and +6V to the proper +12 -12V.
The pedal works great, except that when bypassed, the clean notes have a background noise. The white noise just come up while I am playing.



The other issue is that I have no idea how to wire LED's into my 3pdt switches for this circuit... Any suggestion?

I know it was not necessary to wire the LEDS of the circuit with those cables, but my friend thought that those 3 LEDs should be visible in front of the switches. I didn't explain him that the visible LEDs are just to see the on-off of each 3pdt switch...

Thanks,

[asintoras]

And here are the schematics in case you need them:
.

I found here a guy Galeco that solved the problem of the bypass' bleeding with the following:
"I used the second half of the DPDT to switch the GND between the led and R3/LF347 pin3/C9.", but I have no idea how to do that...

Thanks,