Debugging Help - Guyatone FL3 Flanger

[Kinetic]

I was looking for a good flanger to try and I decided to have a go at the Guyatone FL3 with the mods mentioned in this thread by doc_drop: http://www.diystompboxes.com/smfforum/index.php?topic=83380.0

So, schematic I'm working from:
http://img.villagephotos.com/p/2009-2/1335875/DROP-Jet-Build-Docs.JPG

I didn't have a 50k trim to hand so instead I've socketed the resistor and tried various values, starting with 33k and working up from there to 100k.
I've built on veroboard so I didn't use the perf layout.
One other change, I've swapped around the order of the 2 op amps in U1 so I'm using pins 1/2/3 for the first and pins 5/6/7 for the second, for simplicity based on the layout I've used on my board.

The problem quite simply is that it is not flanging!  Clean signal is passing through with no gain or distortion and no noticable effect.

Voltages are as follows:



Q2:  C 7.5
       B 7.6
       E 7.1

Q3:   C 4
        B 4.5
        E 4.2


TL072 pin 1 = 7.8
          pin 2 = 5.4
          pin 3 = 8.2
          pin 4 = 0
          pin 5 = 5.25
          pin 6 = 8.45
          pin 7 = 1.37
          pin 8 = 8.8

4558 (U1) pin 1 = 4.65
               pin 2 = 4.64
               pin 3 = 3.13
               pin 4 = 0
               pin 5 = 4.5
               pin 6 = 4.6
               pin 7 = 4.6
               pin 8 = 9.1

4558 (U4) pin 1 = 4.6
               pin 2 = 4.6
               pin 3 = 4.5
               pin 4 = 0
               pin 5 = 4.5
               pin 6 = 4.6
               pin 7 = 3.5
               pin 8 = 9.1

MN3207 pin 1 = 0
             pin 2 = 3.15
             pin 3 = 4.46
             pin 4 = 7
             pin 5 = 7.5
             pin 6 = 3.3
             pin 7 = 5.65
             pin 8 = 5.65

MN3102 pin 1 = 7.5
             pin 2 = 3.15
             pin 3 = 0
             pin 4 = 3.3
             pin 5 = 4.3
             pin 6 = 3.15
             pin 7 = 3.96
             pin 8 = 7


Any help would be greatly appreciated.  Thanks!

[doc_drop]

Hey Kinetic,

And I thought that thread had been lost to the sands of time...

I will try to take a look at your voltages and compare them with mine. But, it sounds to me like yours is doing what mine did until I got the bias right. It is a pretty narrow window, so I have a feeling that might be your problem. Too bad you don't have a trim pot, since it is a lot easier than switching out resistors!

I suck at vero, so I am impressed you did this on vero. Have you confirmed all the connections per the schemo? (The first thing I check on my own layouts is the continuity if they don't work at first. Often there will be one little connection/disconnection that screws the whole thing up.)

It is a great effect, so keep at it, you'll be happy you did.

[Kinetic]

I've spent a while looking at it again tonight - found a small error, which I corrected but it had no effect.  I found a 100k trimpot in my parts drawer so I hooked that up in series with a 33k for the bias resistor; tweaking it does cause the odd weird noise but it doesn't get me flanging!

I think that quite simply, the problem seems to be that my LFO isn't oscillating.  Signal is passing through so I can't help but feel that if my LFO would kick into gear then I'd be all set.  I suspect I've got a wiring error in there somewhere that I haven't spotted, easy to do with a big circuit on vero.  If you could post voltages from a working unit that would be awesome, I reckon that would point me in the right direction.

[doc_drop]

Kinetic,

Here are my voltages. It looks like you are correct about not having an LFO. The first thing I found was there are oscillating voltages all over this circuit. I didn't bother to notate the ranges, but I marked all the pins that are shifting back and forth. I also noticed that your TL072 has much higher voltages on pins 3 and 6 than mine. Maybe that is the first place to look? The 4558's look fine.

Good luck, and I hope this helps.


9.25V Power Supply:

Q2:  C Oscillating
       B Oscillating
       E Oscillating

Q3:   C Oscillating
        B Oscillating
        E Oscillating


TL072 pin 1 = Oscillating
          pin 2 = 3.8
          pin 3 = 3.76
          pin 4 = 0
          pin 5 = Oscillating
          pin 6 = 3.77
          pin 7 = Oscillating
          pin 8 = 7.57

4558 (U1) pin 1 = 4.25
               pin 2 = 4.29
               pin 3 = 4.27
               pin 4 = 0
               pin 5 = 4.17
               pin 6 = 4.36
               pin 7 = 4.38
               pin 8 = 8.53

4558 (U4) pin 1 = 4.27
               pin 2 = 4.27
               pin 3 = 4.27
               pin 4 = 0
               pin 5 = 4.27
               pin 6 = 4.27
               pin 7 = 3.37
               pin 8 = 8.55

MN3207 pin 1 = 0
             pin 2 = Oscillating
             pin 3 = 4.24
             pin 4 = Oscillating
             pin 5 = Oscillating
             pin 6 = Oscillating
             pin 7 = 5.25
             pin 8 = 5.24

MN3102 pin 1 = Oscillating
             pin 2 = Oscillating
             pin 3 = 0
             pin 4 = Oscillating
             pin 5 = Oscillating
             pin 6 = Oscillating
             pin 7 = Oscillating
             pin 8 = Oscillating

[Kinetic]

Thanks a lot for posting those voltages, big help.  I've made some progress, LFO is oscillating now but I'm still getting clean signal through at the output.  I'll have another look tomorrow.  Getting there...!

[doc_drop]

Progress is Good!

Time to audio probe?...

[Kinetic]

Got it sorted, I'm flanging away now!  Thanks for all your help 

[doc_drop]

Yeah! Glad to hear it. Way to keep at it till you forced those electrons into submission.

I owe this forum a lot of "help payback", so it was my pleasure to help.

[kermito]

I have no idea if it is okay to hijack this thread, but since the voltages are here already, I'll do it anyway.

I tried to build a slightly modified version of the Guyatone FL-3 flangers, using the schematic provided in this thread (link in the first post): http://www.diystompboxes.com/smfforum/index.php?topic=88971.0
But the thing doesn't work. The dry signal is coming through ok. But no flanger. I checked basic things: bias and supply voltages, 0V at ground...
It appears things go wrong between the depth pot and the 3102. I still have an oscillating voltage at the depth pot, but nothing at the second transistor (Q3). The 3102 has strange readings, I guess: either 8~9V, or 0V. Could it be that the 3102 is broke? Could that explain that there is no oscillation at the second tranny? And what about the voltages posted above: I expected pin 1 of the 3102 and pin 1 of Q2 to have 8~9V, or is there something I do not quite get? (Very possible  )

Also, I designed (or tried to) my own compact perf layout, but do not immediately find a mistake there. 


Any help?

Cheers,

Kermito.

[kermito]

Nevermind. I found it.

After a few days of checking, tracing, double-checking, measuring and then some, I resorted to seeking help on this forum. Only minutes after, I saw an unsoldered connection (at the tranny indeed). 

Anyways, I have learned a lot on this forum for this and previous fx builds, so big thanks anyway.!

Kermito.

[edd101]

yo!

speaking of Guyatone FL3 Flanger, I have built one several month ago, it flanges and the sound is ok, but it is hissy. It hisses like you're at the seaside))) did anyone had a similar problem?

Ed

[edd101]

anyone?!?!?!