Ross Distortion Clone troubleshooting

[romdos]

I recently aasembled this project (see link below) and it doesn't work..I rechecked and double-checked all the parts and the traces, etc. and everything is right.  

I didn't have a germanium 1N270 diode so I used a couple of diodes I already had.  Will this make a difference?  I emailed the guy who did this schematic and he assured me that that design was tested and worked.

Anybody got any ideas other than the diodes that migh be causing it not to make any sound at all?  thanks in advance

http://members.tripod.com/gillcar/id25.htm

[tungngruv]

I'm pretty sure the diodes won't make a difference. Maybe you could check out the DOD 250, MXR Dist + schematics and layouts on Generalguitargadgets.com, they are real similar. Also, I'm not sure but pins 5, 6 and 7 look funky on your schematic (at least in my limited knowledge). Your pedal should work even without those hooked up. Look on this forums DIY FAQ (link above), and towards the bottom of that page, it tells how to sub a dual op amp (what I think you have) for a single op amp. This will make sure you have at least half of the op amp correct so the pedal will work. Let me know how it turns out.

[petemoore]

I've built DIST+ Types using dual Opamps, and singles.
 When I use a dual, I like to ground the inputs for the non-used OA half, or use it for a Micro-amp to drive the DP to more Dist, or buffer to drive a Tone Control.
 Is that board designed for a Dual or single Opamp?...Whatever the case, one must be certain of the pinout.
 Take OA pin voltages and we'll take a look.

[romdos]

Thanks for your replies...I would have repsponded sooner but I didn't get the notice by email that I had replies.

I actually have the original Ross distortion pedal, but was wanting to build a clone that I could play with and try different diodes, opamps, etc. with.
That pinout for 5,6, and 7 is correct as my original pedal is hooked up like that too.

I'm kinda new to all this in-depth electronics (I had circuits I and II in college) so I'm familiar with the basics of electronics, but not the detailed stuff.  How do get the voltage at the pins?  Hook it up and then check it with one probe at ground and the other on the pin?  

Sorry if this is simplistic.  It's just frustrating because I actually built the Ross compressor clone and it worked fine, and this device is a MUCH simpler design, and the darn thing won't work.  The opamp is a 4558  I think it's a single isn't it?  It's got 8 pins

Thanks

[romdos]

Thanks for your replies...I would have repsponded sooner but I didn't get the notice by email that I had replies.

I actually have the original Ross distortion pedal, but was wanting to build a clone that I could play with and try different diodes, opamps, etc. with.
That pinout for 5,6, and 7 is correct as my original pedal is hooked up like that too.

I'm kinda new to all this in-depth electronics (I had circuits I and II in college) so I'm familiar with the basics of electronics, but not the detailed stuff.  How do get the voltage at the pins?  Hook it up and then check it with one probe at ground and the other on the pin?  

Sorry if this is simplistic.  It's just frustrating because I actually built the Ross compressor clone and it worked fine, and this device is a MUCH simpler design, and the darn thing won't work.  The opamp is a 4558  I think it's a single isn't it?  It's got 8 pins

Thanks

[romdos]

Thanks for your replies...I would have repsponded sooner but I didn't get the notice by email that I had replies.

I actually have the original Ross distortion pedal, but was wanting to build a clone that I could play with and try different diodes, opamps, etc. with.
That pinout for 5,6, and 7 is correct as my original pedal is hooked up like that too.

I'm kinda new to all this in-depth electronics (I had circuits I and II in college) so I'm familiar with the basics of electronics, but not the detailed stuff.  How do get the voltage at the pins?  Hook it up and then check it with one probe at ground and the other on the pin?  

Sorry if this is simplistic.  It's just frustrating because I actually built the Ross compressor clone and it worked fine, and this device is a MUCH simpler design, and the darn thing won't work.  The opamp is a 4558  I think it's a single isn't it?  It's got 8 pins

Thanks

[Gilles C]

....Also, I'm not sure but pins 5, 6 and 7 look funky on your schematic (at least in my limited knowledge). Your pedal should work even without those hooked up....

That's right. It would work without the second half connected that way. But it's just one way to make sure the unused half won't generate any noise by oscillating.

http://www-inst.eecs.berkeley.edu/~ee43/f04/material/lab6/guide6.pdf

You can try it without the diodes..

The 4558 is a dual opamp. Just like the TL072 and the ECG778A in the schematic of the Ross Distortion.

I'm kinda new to all this in-depth electronics (I had circuits I and II in college) so I'm familiar with the basics of electronics, but not the detailed stuff. How do get the voltage at the pins? Hook it up and then check it with one probe at ground and the other on the pin?

That's right. With the meter on the DC Voltage scale, you should read around 4.5V at pin 3 of the opamp. You should also read about the same at pin 1.

You could try using a homemade audio probe to check at pin 3 and 1 if you have some audio. If you have some audio at pin 3 but not at pin 1, the opamp is bad or the problem is at the output somewhere. If there is no audio at pin 3, the problem is before.

You can read about builing a probe there.

http://www.diystompboxes.com/pedals/debug.html

I have a small low power that I use just for that.

Gilles C  (or gillcar...)

[Gilles C]

Oh, I forgot! and I can't add/edit...

http://users.pandora.be/educypedia/electronics/analogopamp.htm

A lot of reading about opamps.

[romdos]

Thanks a lot for your replies...I'll check this stuff out, cuz I'm at a loss as to what could be wrong.  The pedal looks darn cool with the light on, just doesn't do anything to the sound.