Another Sunking Topic

[Hirti]

Hi Guys!

This is my first post here although I have been reading here for the past few month.

I have a weird problem with my Sunking. The gain pot only works in the last quarter. From 7 o'clock to 15 o'clock I don't get distortion and from 15 o'clock to 17 o'clock I suddenly get distortion. I checked if there are any shorts but I couldn't find any.
I swapped the ics and the diodes. The voltages of the ics are correct. I desoldered all of the caps and checked if one of them is dead - no. I soldered every solder joint again just to make sure there is no problem there. I even split the gain pot up into two independent pots but the problem was still there.
I substituted the 27n cap with a 22n cap but I don't think this could cause the problem.
\\Edit: Oh, and of course I checked the wiring.

I'm sure there is a problem somewhere because otherwise this would work correctly but I'm lost here.
Does someone know what I could try next?

Please excuse my odd englisch, I'm from Austria.


Daniel

[gtr2]

Did you use a linear taper (kB) for the gain pot?

Josh

[Hirti]

Hi!

No, I used a log pot because I accidentally ordered the wrong pot. I'll get the right one soon. The weird thing is that I had the same results with the gain only usable in the last quarter when I tried it with the two separate pots - those were lin pots.  

Edit: One other thing: I get unity gain (output) at about 13 o'clock. This is weird, right?


Daniel

[gtr2]

Sorry but you need to be more specific in your post.  Listing the approximate settings for the both the volume and gain pots would help.  I don't understand this line:

Edit: One other thing: I get unity gain (output) at about 13 o'clock. This is weird, right?

What pot are you talking about and how are the other pots set?

This thing can have a lot of boost above unity with the gain turned fully counterclockwise and just adjusting the volume knob.

I'd replace the dual gain pot with a kB and report back so were are talking apples to apples 

Plus are there any other changes you didn't mention?

Do you have the diodes in or are you waiting to tie them in on a switch?  If you don't have the diodes in you won't get overdrive until around the last quarter turn on the gain pot.

Josh

[Hirti]

Hi!

I made a video. I thought it would explain itself more than my words would. As you can see I replaced the pot with two kB pots.

(Woah, Youtube compression really sucks but I think you get what I mean.)


Yeah, there are 2 or 3 resistors I changed because I didn't have them in stock. And I changed the tone cap to 6,8n. I don't think this could cause the problem but who I am to judge? The diodes are in.



Daniel

[gtr2]

It sounds like a klon, I mean sunking...

But your right, the overdrive is not quite where it should be.  I'd say it's close but it doesn't get enough drive when your gain pots are maxed.

Ok, we need some more info:

What resistors did you sub and with what values.

What diodes did you use?

Can you list your voltages for the IC's for each pin?  If your unsure how to do this look at the other sunking problems thread.

Josh

[Hirti]

Hi!

The Voltages:
IC1    
Pin 1   4,61
Pin 2   4,61
Pin 3   2,11
Pin 4   0
Pin 5   4,58
Pin 6   4,61
Pin 7   4,61
Pin 8   9,26
   
IC2   
Pin 1   4,63
Pin 2   4,61
Pin 3   4,61
Pin 4   -8,9
Pin 5   4,61
Pin 6   4,61
Pin 7   4,6
Pin 8   16,78
   
IC3   
Pin 1   9,26
Pin 2   4,62
Pin 3   0
Pin 4   -4,42
Pin 5   -8,9
Pin 6   4,68
Pin 7   7,12

Oh, some of those voltages seem really off..
Diodes are 1N34A. But I also tried BAT41, they don't really sound that different.

Ok, I checked again and those are the values I changed:
R5 = 4k7
C7 = 82n
C13 = 22n
C15 = 6,8n


Daniel

[gtr2]

The only one that looks off is pin 3 of IC1.  What did you use for IC3?

[Hirti]

I used an ICL7660S.

[gtr2]

I don't know if it's the case here but you may want to try using a 7660SCPA.  It seems like a lot of problems come from not using the exact IC specified on the build doc.

[bigmufffuzzwizz]

I don't know if it's the case here but you may want to try using a 7660SCPA.  It seems like a lot of problems come from not using the exact IC specified on the build doc.

I'm noticing that too. Quite a few people have problems with the IC.

[Hirti]

Oh, okay, I'll try a 7660SCPA. I'll also build the Sunking new from the beginning and swap all the parts. Just to make sure I didn't accidentally made a solder bridge somewhere or something like that.

Thanks for your help so far!



Daniel

[Liam]

Hi Daniel,

Just a thought.  Here in Europe "A" is usually linear, and "B" is log.  For USA and some other places this is reversed.  For the Sunking you need linear for the tone and drive controls, although log works really well for the volume.

Hope that helps if you'd not noticed.

Liam

[josetxu]

I think I maybe have the same problem. From 0 to about 2PM I've a cleanish sound (no distortion) and from that to 10 I've got all the drive, but I think is less than the drive I heard from the clips in youtube (maybe is also amp drive?), I've used 1n34a diodes from banzai (Germany) but I've have yet to try others. My voltages seems ok (a little lower than that from the proyect PDF but also the batery level is lower):

Battery: 8,63v

IC1:

Pin1: 4,29v
Pin2: 4,27v
Pin3: 3,28v
Pin4: 0v
Pin5: 4,24v
Pin6: 4,27v
Pin7: 4,28v
Pin8: 8,54v

IC2:

Pin1: 4,23v
Pin2: 4,24v
Pin3: 4,24v
Pin4: -8,18v
Pin5: 4,23v
Pin6: 4,24v
Pin7: 4,24v
Pin8: 15,29v

IC3:

Pin1: 8,49v
Pin2: 4,24v
Pin3: 0v
Pin4: -4,02v
Pin5: -8,16v
Pin6: 4,01v
Pin7: 6,43v
Pin8: 8,47v

Do you resolve your problem?

[gtr2]

What did you use for IC3?