Messages

Yup, it can be tough to find everything in one place.  Plus, certain sites have better pricing for certain parts, so even with separate shipping it can be more financially savvy to pull from various sites.  I tend to hit Smallbear and Pedal Parts Plus the most, plus I have a nice little local shop for bits I need in a pinch.

[Top set]

Done and done.  

Okay, the weirdness has begun at the gain pot.  Now, I don't know how exactly a pot is *supposed* to function, but it would stand to reason (in my mind at least) that both sets of lugs should behave the exact same way when the pot is turned, as a dual-gang pot is essentially two pot stacked on top of each other and controlled by a single shaft.  If that's true, it doesn't appear to be the case for this pot.  I've described the resulting audio below with the pot starting at all the way turned down and then cranked all the way up...

Top set
Lug 1: audio is always on
Lug 2: audio starts at full volume and evenly reduces to full quiet
Lug 3: no audio

Bottom set
Lug 1: audio level starts at full quiet then appears to reach its loudest level after barely 1/4 turn
Lug 2: no audio
Lug 3: audio level starts at full quiet, turns up to full volume, then all the way back down again to full quiet

Due to time I've got to wrap up working on this thing today, but this doesn't seem right to me at all.  Did I install a faulty pot?  My local building buddy informed me of the trick of using resistors to make the pot circuit wide open, but I wasn't in a place where I could write down any notes.  Anybody know this trick and willing to give me a quick rundown on how to o it?  I still think the pot is a culprit, but I'm not going to rule anything else out.  Also want to replace IC1, it may have gotten overheated while I had the wrong charge pump in there.

Okay, built me an audio probe.  Now to hit the diystompboxes link and start the debuggage...

I'm going to presume the pedal should have power running to it, yes?

An audio probe is simple to make and you most likely have the parts to make one.

http://diy-fever.com/misc/audio-probe/

I use the 1/4" jack socket version so I can use a longer cable if needed.

An audio probe is essential to debugging.  Follow along through the circuit with the schematic, it will help you locate where your having problems in the circuit.

josh-

Hmmm... does this mean there are things I can do with an audio probe that I can't with a DMM as far as troubleshooting and debugging?

[something]

It appears from comparing the datasheets that it may work...  It's worth a try at least.

You can buy the max1044 from small bear.

http://www.smallbearelec.com/Detail.bok?no=244

I'd love a "local" shop in my area.  There pretty non-existent in the Philly area.  

josh-

Yeah, it's nice to have a local store, it's where I get most of my caps & resistors these days.  

I just got back from picking up the TC1044's.  Threw one in, still no change from the gain pot when plugged in, but I also don't have the diodes in there.  Going to check the values on the ICs again...

***EDIT*** Some success, the values are now where they should be on the ICs.  But again, still not getting any significant change when turning the gain pot, which seems very strange to me.  Even without the diodes in there, methinks the gain pot should do something...  Could it be the pot is bad?  It also seems to me that I should hear some kind of difference with the diodes back in there.

[something]

It appears from comparing the datasheets that it may work...  It's worth a try at least.

You can buy the max1044 from small bear.

http://www.smallbearelec.com/Detail.bok?no=244

I'd love a "local" shop in my area.  There pretty non-existent in the Philly area.  

josh-

Yeah, it's nice to have a local store, it's where I get most of my caps & resistors these days.  

I just got back from picking up the TC1044's.  Threw one in, still no change from the gain pot when plugged in, but I also don't have the diodes in there.  Going to check the values on the ICs again...

***EDIT*** Some success, the values are now where they should be.  But again, still not getting any change when turning the gain pot, which seems very strange to me.  Even without the diodes in there, methinks the gain pot should do something...

[L]

I went back and found this thread: http://www.madbeanpedals.com/forum/index.php?topic=81.0.  Says you can sub a MAX1044 for the 7660SCPA (which I can't find anywhere, not even futurelec).  Brian said in that thread that you can also use a TC1044... My local shop has LTC1044s which, after a bit of research, are LINEAR TC1044s, and "Linear" appears to refer to the manufacturer.  I just want to make sure it's work the trip before I drive on up to my local shop.

I did find the 7660SCPA IC at Mouser, they've got 'em pretty cheap (individuals at $1.08, between 10-25 qty. $.90, group buy, anyone??).  I'm trying to determine if I should order the SCPAs from Mouser or if I can just head up to my local shop and pick up those LTC1044s...

Triple-checked all my caps, their polarity is good.  Also checked my 4001s, polarity is good there as well.  Just checked them both with the diode setting on my DMM, both are registering between 0.593 and 0.596... does that sound right?  

I suppose it's a good sign that only those three values are wacky and they appear to all be tied to the charge pump.  I just remembered that I have a couple more 7660s, I should try swapping it out for a new one.  Let me try that first, if it's still wacky I'll update this post with a shot of the topside and we'll go from there.

**EDIT**
Swapped out the charge pump, values still aren't matching what you said they should be, and they're different from what they were before.  IC2 Pin 4 now reads 5.81, Pin 8 reads 8.45.  IC3 Pin 5 reads 5.38.  Tried running my guitar through it to see if I could get sound.  Bypass signal is just fine, but the effect engaged now has a continuous digital "farting" sound, for lack of a better term.    Here's a shot of the topside:



I've got one more 7660, I'll try it, I suppose.  I'm starting to think I need to get a totally different IC though, either the SCPA version of the 7660 or a MAX1044.  

[IC1 (TL072)]

Okay, testing the IC's.

IC1 (TL072)
Pin 1: 4.78
Pin 2: 4.78
Pin 3: 1.25
Pin 4: 0.00
Pin 5: 4.72
Pin 6: 4.78
Pin 7: 4.78
Pin 8: 9.52

IC2 (TL072)
Pin 1: 4.77
Pin 2: 4.77
Pin 3: 4.72
Pin 4: 0.57
Pin 5: 4.72
Pin 6: 4.78
Pin 7: 4.79
Pin 8: 8.23

IC3 (ICL7660CPA) -should be SCPA, but like you said, it should still work.
Pin 1: 9.52
Pin 2: -0.02
Pin 3: 0.00
Pin 4: 0.46
Pin 5: 0.57
Pin 6: 2.62
Pin 7: 0.24
Pin 8: 9.52

Gain Pot (100kB dual)
**Top Row
Lug 1: 4.72
Lug 2: 4.72
Lug 3: 4.71
**Bottom Row
Lug 1: 4.71
Lug 2: 4.71
Lug 3: 4.71

Double-checked all my solder joints and points with a magnifying glass... easily the cleanest soldering job I've ever done.  Also double-checked the 27k resistors in the voltage divider section, both are spot on. 

Thoughts

Gotcha... I think.    Still learning.  I checked those two 27k resistors earlier today and they appear both to be the correct values.  I'll have to check the IC and the gain pot tomorrow when I get back to the office.  I sure hope it's not the gain pot, I installed the one you sent me, and I would hate that you accidentally grabbed a dud! 

My local building buddy thinks it's possible having the wrong charge pump would alter the amount of audio signal, but I can't remember exactly where along the signal chain he said it would be and how he described it.  Something about only half the audio signal going where it needs to go.  He's substantially brainier than I am at this, so I thought I'd pass his thoughts on to you and see what you think.

I'm using the typical Boss power supply, didn't wire up a battery connection.  Never do, batteries irritate me.  I've got a Voodoo Lab Pedal Power 2 Plus, would that be "safer" to power it with?  Ideally I'll be powering from that source anyway.

Got a guide or walkthrough on checking IC pins and the gain pot lugs?  Links are always good.  Thanks, Brian.  You're the man.

[is]

Gain pot is definitely wired correctly.  I double & triple checked the lugs.  *CORRECTION TO ORIGINAL QUESTION: There is something going on when the gain pot is turned: there's an extremely slight difference in volume.  

What's the Vb?  Still noob-tastic here & there.  

It's certainly possible the diodes aren't set up right.  Does it look like there's possibility of shorting from the photo?  As hewn together as it may look, I took extreme care in preventing any shorts as that was a major problem with my very first build.  Warming up the soldering iron now, will disconnect the diode switches and see what's what, post again shortly...

BTW, this thing will at least look amazing.  The faceplate you sent me really sets it off.  I'll be that much more excited when it's working!

***UPDATE*** Same behavior as before when the diodes are removed from the signal path.  The gain knob still decreases the volume slightly when turned up, and the high-pitched whine (presumably from the charge pump IC) goes away when the gain pot is as 12 o'clock high but increases when turned in either of the other directions.

Finally got my 10kB pots in today so I put them in and fired this puppy up and got two undesired results:

First, got the high-pitched squealing a few other guys have been talking about, so I checked the charge pump IC, and it's the CPA rather than a SCPA.  That should be an easy fix once I can get to my local shop and find an SCPA (although I ended up with the CPA version the last time I went there). 

Second, the gain pot does nothing.  No change at all in the overdrive/clipping level when turned.  Tone and volume pots function as expected.  I did Madbean's Eleventy Bajillion Diodes mod (found here: http://www.madbeanpedals.com/forum/index.php?topic=1107.0), so I don't know whether I did something goofy or what.  Double-checked all my wiring, including the wiring going two and from the switches for the diodes mod.  Here's a couple shots of the guts:




Thanks in advance to any and all who have input and can help me get this puppy running! 

[dang]

Yea I did my first customer build for 100 dollars. I could have charged more but it was my buddy. Jacob is totally right. The most time consuming is the wiring and enclosure detailing. And you should charge for your time. I think if your buddies getting a klon clone for $100 thats a hell of a deal!

You got that right.  Wired up my Klon today, just missing the 10kB pots (dang Smallbear forgot to ship them along with the rest of my order).  Definitely worth the extra effort to keep everything clean, but dang if it didn't take a good amount of time.  Were I building it for a friend (and I might, I've got another board and a guy who's very interested), I'd probably start at $150 for a friend, $200 otherwise.  I will have spent probably $80-85 on mine just for parts.  Granted I got a custom finished enclosure and also bought a faceplate from Madbean, but even so I think I did quite well against the original one a fellow builder here in town saw for sale on craigslist... dude is asking $795 for a "well-loved" Centaur.    Methinks $150 is the deal of the century compared to that.

I've always been a Tubescreamer & equivalent guy, so when I decided to branch out, I went for the Krankosaurus.  Nice to get Marshall-y tones from a '71 Super.  I've never been a fan of the Rat, so I say go for the Krank.  But it can also depend on the amp you're running your rig through. 

Yes, that's a combination series and parallel circuit. The top two diodes are in series with each other, and in parallel with the lower diode.

Combining diodes is an interesting thing. Generally, we all use one type of diode for clipping in a pedal. But, it could be interesting to try mixing diodes, for example, using silicon in series and germanium for the parallel diodes in the asymmetric clipping above.

The list of diodes used by Brian and I are earlier inthis thread.

Jacob

I noticed when I went back and looked at Madbean's post that his asymmetrical example was the mixed diode one that used three diodes.  Would love to try that one, but I'm not sure if I actually have any 1N914s.  I bought a bunch of stuff off meowy, but there were some unlabeled diodes that look exactly like the 1N34As he sent.  He said they might be 1N914s in his original Buy/Sell/Trade post, but I don't know how to tell.  I shot him a PM asking about it.