A beginner Needs help builing MXR distortion plus.

[Izzy]

@ Gibson GM

Yes Sir I will try to follow your suggestion. I appreciate your help.
Yeah and please be around I might still have some more question Even If I do the easier way like you said


@ Mark Hammer

Thanks Once again. All my remaining parts should arrive in few days I will let you know If I have any more questions.

[aron]

I still think you should try and make a simple circuit work on the breadboard first. The MXR is really too complicated without some kind of breadboard "layout". There are too many things that can go wrong.

[Izzy]

Yes, I am going to do this in bread board. Infact I did it yesterday night which became too messy because of the long leads of resistor and capasitor.
I am going to do them again by cutting them.

Main problem was the berad board was too small.

[GibsonGM]

Oh boy, you are determined, Izzy, LOL!    I do believe you'll get it going.

I took a minute and edited R.G.'s MXR schematic (link below), removed the switching etc. so you can just follow it to get running on a breadboard easily.  Quick Note, tho - I request that someone QA's this before you begin! Aron, have a look?  I omitted the switch, and made battery connections direct.
Thanks.
Mike
http://i92.photobucket.com/albums/l9/generalguitar/MXRsimple.jpg

[Izzy]

Hats Off to you!

Thanks !!!!

Yes it definately made easier to under stand.

One question though.
I am trying to use Ac adapter for power supply through 9v battery connector cable.I guess that shouldnt be any problem right?

By the way. I reconstructed it again. Might look messy but still  see if you can advice anything.
This is just halfway done. Few more circuit parts should arrive soon. Then I will show you again

[aron]

hmmm he might get it going.   

The schematic should probably say zero volts instead of -9.

Looks ok though to me.

[GibsonGM]

True, Aron, LOL...since "-9v" IS "MINUS 9 volts"....I shoulda put "- battery terminal".  Good enuff for our discussion & 4 minutes editing.

Wow, Izzy, that is NEAT!!!!  Much nicer than my usal Rat's Nest!! I believe you have the idea.  You'll get it up and running. 

Using a 9v adaptor is fine, as long as the voltage, current requirements and polarity are correct.  This is not a very critical circuit.
Maybe setting up the 2 jacks you'll need with wires soldered to them would be helpful...or just use jumpers if you want. I always temporarily solder 3 wires to each pot, too, for breadboarding.

It's coming right along...barring any wiring mistakes, awesome!   

[Izzy]

Hi guys I finally got my remaining circuit element .
But Smallbear electronics didnt label anyone of them.
So I am having lil hard time finding out which one is which.

I got Ge 1n271 diode. But which one is positive and which one is Negetive end.
I think the one side with bigeer metal piece inside is Cathode. But I want to make sure!
On the lower end of glass its lightly dark color.

Please help me to make sure that it is cathode.
And also I had ordered 10 pf Caps. The one they sent me doesnot have any labels. How can I be sure its the one with 10pf?

[Izzy]

Can please some one help me here?

[Barcode80]

the dark end should be situated in the direction of the black band in the schematic. i believethat makes it the cathode.

[Izzy]

Ignore my above post.

I tried to run it today. Damn and it didnt worked. I dont know why?

I didnt want to use bread board it makes so confusing.haha
Now how could I debug? Or can anyone see where I am doing wrong?

I tried to find mistakes but I couldnt.
I have Radio shack 20$ multi meter but I dont know how to check for continuity?

I would be so glad if anyone would look at these pics and possibly find out error? May be?


I am using adapter here for 9v through battery connector.
Does anyone think changing polatiry of the adapter will help?
I am scared to try that without some one gives me green signal..

I am waiting for some helpful post.
Please anyone..

[Izzy]

Yeah and this was based on  these two schematics.

http://www.tonepad.com/getFile.asp?id=4

and

http://i92.photobucket.com/albums/l9/generalguitar/MXRsimple.jpg

[Izzy]

DAMNNNNNNNNNNNNNNNN
IT WORKEDDDDDDDDDDDDDDD


Sorry Volume was turned down before..hahahah
I am SO happy
Thanksssssssssssss to alllllllllllllll

[GibsonGM]

Hi Izzy, good work! It's late here, but check what I've circled, should be 4.7K (yellow violet red, can't tell if it's red or brown in your pic).  I can't see the connection for the 1M gain pot there, either.   The purple wire is the feedback loop, to the 1M resistor and pF cap, right?

Red circles on 1 M resistors...these connect together; please fix.  1 end of 1 goes to +9v, the other end of both goes to ground (seems ok to me from what I can see).  The 1uF cap connects to the junction of them, and goes to ground.  This is your biasing setup.

With your meter, measure 9v at your power in...connect black lead to power supply ground, probe with the red lead.  Set meter for "DC volts".   You oughtta get 9v on the other power supply lead.   Next, leaving black probe connected to ground, check the junction of the 2  1M resistors...you should get about 1/2 your supply voltage (around 4.5 V).   You should also read this at pin 3 of the IC.  You should have 9V at pin 4, and just about zero at pin 7.  All ground points should be about 0, and all +9v points, of course, +9v. (I'm not sure if your lower row is all ground, or mixed + and ground, check those connections!).

Please post those voltages, that will get you started!  And another pic, maybe edit the pic to say "input tip"  "output tip" "+9v",  "-9V",  "to 1M gain pot" etc; that will help us diagnose the problem! 
Keep it up, you're getting close...but I have to go to bed!  Someone will help; I'll check back tomorrow...work on getting power to the IC, and the correct bias to the inverting input pin...

[GibsonGM]

Hey, ALLRIGHT!!!!!!!!!!!!   Good work, Izzy...you will enjoy your new toy!!
Next, we will go over how to perfboard the thing, and connect a switch! I'm glad we didn't have to go thru too much debugging, LOL.

Happy Playing!

Mike 

[Izzy]

Sure Sure. I woul be very happy if you could give me some knowledge on how to use LED using DPDT (Non true bypass).

Yeah one more thing I am getting some hummmmm

How to reduce it?

[petemoore]

Yeah one more thing I am getting some hummmmm
  *Could just be the open circuit spread over the breadboard.
  Once it's covering less area, it should become less of an antenna, also inside a shielded box tends to reduce noise.

[Izzy]

Thanks Petemore.

@ GIbsonGM

Yes Sir I checked the 4.7k resistor, and I think its red. Even though it looks like redish brown, It should be red  I just checked the packet and its 4.7k.

And about those 2 1M resistor, I checked it again and I think its right. I guess the picture was confusing.
I have drawn  the flow on top of the pic. I think it should be right.






With your meter, measure 9v at your power in...connect black lead to power supply ground, probe with the red lead.  Set meter for "DC volts".   You oughtta get 9v on the other power supply lead.   

[/quote]

[Izzy]

Hi Izzy, good work! It's late here, but check what I've circled, should be 4.7K (yellow violet red, can't tell if it's red or brown in your pic).  I can't see the connection for the 1M gain pot there, either. 

Ohhhh Now I see what you are saying.
Sorry , Then I think it is brown. Thats why I was wondering "why this red looks like brown to me???"haha


That mean it is 470 Ohms not 4.7 k. Damn I must be misread it while buying parts.
So whats the effect of being  .47 k in place of 4.7 k??

I would love to know...

[GibsonGM]

I would pop the resistor out of there and measure it with your meter (and get used to doing that, LOL)...you do have ohms, current, and continuity testing on there, don't you, Izzy?   Having a lower value resistor in that particular place will just make your 1M gain pot have that much "more" effect...4.7K is the minimum value for the leg of the ckt there, and you've made it even lower.  In this pedal, it will probably just not sound as good until you get your gain pot up to 4.3K.  No big deal here; just change it before you solder the board up.  You did it right; or it wouldn't work! I see nothing else wrong that jumps out at me.

See if you can get a big Radio Shack package of a variety of resistors...they have them in ALL the common  values, 1/4watt, you won't need to buy any more for a couple of years, only like $12...I check most resistors w/my DMM before installing just for the heck of it.  In some places wrong values can burn things out.

I like that you drew on your breadboard pic w/colored lines..makes it easier to answer questions!

To see what everything does in action, make an audio probe (search in forum for how to) to use with your amp.  You can then test the signal path all along the circuit to see what changes are happening, esp. after the op amp before and then after the diodes!   Don't probe the power supply or grounds, tho, makes UGLY noises (don't forget a blocking cap on the probe!!).