Another pedal another problem

[TreeSlayer]

dang! I see also! you have an '09 etching! I was looking at a '10 version. looks like you had it right the first time! this is the '10 version

[RobA]

dang! I see also! you have an '09 etching! I was looking at a '10 version. looks like you had it right the first time! this is the '10 version

I think though that his regulator should still be the other way around. The layout to the regulator still looks the same in both docs. It's just the regulator image that's different.

Edit (for clarity):
The input pin should still be to the left on both the '09 and '10 docs.

[TreeSlayer]

dang! I see also! you have an '09 etching! I was looking at a '10 version. looks like you had it right the first time! this is the '10 version

I think though that his regulator should still be the other way around. The layout to the regulator still looks the same in both docs. It's just the regulator image that's different.

Edit (for clarity):
The input pin should still be to the left on both the '09 and '10 docs.

I tend to agree. i'm trying now to compare the two. here's something that might be of intrest for diagnosing. I built one of these and it's a tremendous help! it's the "Tiny Tester" http://www.jmkpcbs.com/JMK_PCBs/Store.html

[RobA]

That could be very helpful. I've got a signal generator built into my computer's audio interface that has been very helpful. But, it's a pain to use. One of these would be much nicer.

[Guybrush]

Oh man, sorry for the confusion. I thought I had the newer version of the build doc as it has the fizz lift on it and the one that TreeSlayer posted above doesn't.

The tone generator seems really useful. I'll get one orders soon.

In the meantime please could someone tell me how to hook up my test rig to use the audio probe? Do I just hook everything up as normal or do I have to unclip the Out wire so that the signal goes through the probe? I'm not at home so can't try it out.

Thanks again.

[Haberdasher]

Hey guys.  Here is the doombutter v1 build doc

[RobA]

Hey guys.  Here is the doombutter v1 build doc

Thanks for the link. Now I'm even more confused because the the other '09 one says v2 in the title but is actually this one which is clearly ver.1 in the doc.

Oh well, it doesn't matter. This is clearly the one we are working on here.

[Guybrush]

Hey guys.  Here is the doombutter v1 build doc

Thanks for the link. Now I'm even more confused because the the other '09 one says v2 in the title but is actually this one which is clearly ver.1 in the doc.

Oh well, it doesn't matter. This is clearly the one we are working on here.

Yep this is the one I've been been building (using one of your great etches). I might have screwed another one up!

Seems like theres a few versions of this circuit loating around.

[RobA]

...
In the meantime please could someone tell me how to hook up my test rig to use the audio probe? Do I just hook everything up as normal or do I have to unclip the Out wire so that the signal goes through the probe? I'm not at home so can't try it out.

Thanks again.

No problem on the version. I think we have the right doc to go by now for your build and all is cool that way.

Did you check R3? If that one is off, there won't be any audio coming out.

As far as using your audio probe goes, I don't have a built probe, so what I'm saying here is based on my assumptions about how yours works. I assume you have an output jack that's got a decoupling cap before it and connections for ground and the probe? If so, you'd just hook up the ground of your probe to the ground network of the pedal and then use the probe to contact the different parts/pins. You shouldn't need to disconnect the pedals output jack. Just not having anything plugged into would essentially do that anyway even if you did have to.

Pretty much, probing for audio through the audio path is just hooking up an output at each point. The only thing you really need to account for is that signal might be biased at the point you are listening to it, so your probe needs the decoupling cap that I assume is already there.

If you can send me a link to the docs for your test rig, I can look and see if there is anything else to note about how to use it.

[Guybrush]

So...

I just nipped home from work and hooked the circuit back up to my test rig with the idea of using my audio probe on it (thanks for the advice RobA) and the bloody thing worked! I've no idea what changed but I'm getting sound loud and clear. Baffling! There is still something wrong though as the internal LED is not lighting up which will obviously be having an affect on the effect if you catch my drift? If I tap the circuit/wires etc the LED occaisional lights up for a split second which leads me to believe I have a bad connection/solder joint somewhere. Does this sound possible?

On a related note, what does the LED/LDR 'do' to the effect? As I have said the LED isn't lighting up but the effect seems to be working somewhat without it.

Thanks again!

[pryde]

Yes if you are tapping wires/components and getting intermittent signal then it is most likely a bad solder joint/connection. It may be a good idea to reflow all solder joints. Looking at your pics, besides some possible bridges, it also appears you may have some cold joints as some look dull and "balled" up. You should be striving for a nice, shiny hershey-kiss solder joint.

Making progress, your getting signal 

[RobA]

Maybe you've discovered some new form of self healing silicon?  

Seriously though, that is good. I've never built this effect, so I have no idea what it's supposed to do.

From the schematic, I'm guessing it's a bit of an amp sim/overdrive with a delay whose delay time is modulated by the volume envelope of the guitar.

The LM386 must be working at least somewhat because you wouldn't get any audio otherwise.

The PT2399 could easily have been damaged when the regulator was smoking.

It would be a good idea to check the voltages on the power pins of the chips and the regulator to see where you are at.

[RobA]

Definitely check your joints for the LED. Particularly look at the Track pot's joints and C3.

One question about the solder joints, are you using lead free solder? I ask because there are two things to consider. The first is that a lead free solder is harder to see a cold joint with. It tends to look frosted even when the joint is good. The second point is that if you are using lead free solder, you need to use a higher temp with your iron to get good flow.

[jimilee]

Sometimes my testing rig goes stupid on me too.

[Guybrush]

Sometimes my testing rig goes stupid on me too.

I was wondering if it was my test rig. It was the first thing I built so I might open it up and have a look at how bad my soldering is!

One question about the solder joints, are you using lead free solder?

Yes I am. I was using leaded stuff and started to get a tight chest so switched to lead free some time ago. I bought a much better soldering iron yesterday and did some work on another board last night at 400C/750F. Is that going to be hot enough to get nice solder joints with lead free?

It would be a good idea to check the voltages on the power pins of the chips and the regulator to see where you are at.

Will do. Where can I find what the voltages of the IC should be? I can't see them on the schematic.

Sorry for all the questions. I've only built 3 relatively simple pedals before and I'm encountering a lot of 'firsts' with this build. There's always more to learn!