Bloviator Contour pot doesnt work.

[Rethfing]

Ahoy!

Few weeks ago I built Bloviator circuit (I etched my own PCB). It worked from the beggining, but I noticed that turning Contour pot doesnt affect sound at all. May this be because its responsible for low frequencies?

I checked my soldering - its great (it was very easy, PCB I made looks nice and clean).
I checked my parts very carefully - they are all fine.
Wiring - just jacks, pots and power - nothing to be wrong here since the circuit works.
I used sockets for ICs.

Any clues?

[madbean]

When you turn the contour you should get an increase in the lower frequencies and it should be very audible. Any possibility you have stray continuity between the wiper and lug3? This would cause it to stay fixed and not work properly.

[Rethfing]

Unfortunately the pot is fine, I just desoldered it and checked it with my multimeter (black wire to the 2nd lug, red to 1 or 3 along with twisting the knob - it shows proper values). Well im going to check the board with MM to see if there's any connection I cant see, but first im going to clean it with alcohol.

[Rethfing]

Still nothing

[madbean]

Can we have a pic of the top and bottom of the PCB and your voltage readings on the ICs?

[Rethfing]

Sure thing! Here are the voltages, they seem OK to me:
IC1 - TL072:
1. 4.04
2. 4.04
3. 3.69
4. 0
5. 4.04
6. 4.04
7. 4.08
8. 8.23

IC2 - TL071
1. 0.14
2. 4.04
3. 4.04
4. 0
5. 0.15
6. 4.04
7. 8.23
8. 0

IC3 - TL074
1. 4.04
2. 4.04
3. 4.04
4. 0
5. 4.04
6. 4.04
7. 4.04
8. 4.04
9. 4.04
10. 4.01
11. 8.23
12. 4.00
13. 4.10
14. 4.04

Here are the photos:
http://i48.tinypic.com/add9ci.jpg
http://i50.tinypic.com/2j26pnl.jpg

Finally found some way to make good photos with cheap camera
Hope that helps!

[madbean]

Okay,

You've counted the pins backwards on IC2. Pin1 1 is top left next to the u-shaped indent, whereas you've counted pin1 from the top right. IOW, 9v goes to pin4 and ground to pin11, not the other way around. But, that's not a big deal. You have the IC in the right way which is what counts.

Second, you've used 220k instead of 22k in every spot on the PCB. You need to change those to 22k

For carbon film it should be red/red/orange, not red/red/yellow.

[Rethfing]

You mean IC3 (I wrote IC2 twice). Thanks for that, I looked at the dot on the IC which is in the back of the IC

About those resistors... Daaaaaaaaaaaaaaaamn! How could I miss that? I must have wrong value written on my 220k resistor bag + Im obviously blind. Well thanks for that Brian and sorry for my noobism. Im going to correct that tomorrow (we live in different time zones and its already 10pm here!) and see if it works. Thanks again!

[madbean]

Hey no problem! It could happen to anyone. Hopefully that will fix the issue.

One aside: I actually never read resistor codes myself up until about 2 years ago. Increasingly, I found it to require more work in the end NOT to read them, so I spent a few days forcing myself. Now, I can be very lazy and not have to pull out others to compare the colors or use a DMM.

[Rethfing]

Damn this thing is great! On near max Process and Contour in half it gives amazing acoustic feel on clean channel of my CHEAP Crate FW15R. It now sounds almost tube. On distortion it does great job un-mudding the amp. This baby is awesome, its gonna get boxed for sure. Im feared of what it will do on my Peavey Bandit!

Thanks a lot Brian for this great project and for your help, will definitely stay here for long

[jimilee]

Is there any noise? I have a bbe sonic stomp that I think is noisy, and I'm looking to replace it

[Rethfing]

No its not noisy at all and I have tested it without enclosure. Its really a simple built, few elements, but the result is amazing. I just cant wait to drill enclosure and put it in

[jimilee]

I just cant wait to drill enclosure and put it in

[gordo]

Oh by the way, resistor misreads are not confined to "noobs" by any means.  I still manage to mangle some values from time to time.  Especially the 5 band resistors.  It's more of a brain fart issue for me.