ada flanger help?

[daverdave]

How do, I've just finished building the sad1024 ada flanger and it's not working. I haven't calibrated it since I don't have an oscilloscope and I don't know how to do it without one. There's a signal going through but no flanger sound, just a kind of faint oscillation sound that changes speed with the rate. Can anyone point me in the right direction?

[mdh]

Charlie had a post laying out the basics of getting it calibrated without an oscilloscope here, and I think there may be some further discussion downthread from there.  Also look at the "Calibration and Bench Test Procedure" link on his his main  ADA Flanger  page.  I calibrated the new MN3007 design without an oscilloscope, and lots of people around here have done the same.  The tricky thing about the original ADA doc on Charlie's web page is that the numbering of the trimmers doesn't always match up.  But the numbering in Charlie's own post on the subject should be right.

[daverdave]

Ah cheers matey, got it working but I need to properly sort the sweep out, I don't have the patience today though. Thanks for the help.

[oldschoolanalog]

Did you make sure all jumpers are in place?
Is the CV jack wired according to the schematic?
Recently somebody else had similar issues and these were the answers.

[daverdave]

I made it with moosapotamus's version 3 board, so all the jumpers are actually already on the board (I hope). Pretty sure I wired everything right, it's flanging but it needs calibrating properly, well at least I think it just needs that. Hopefully I'll haveit up and running over the weekend.

[mdh]

I think Dave is referring mainly to the expression pedal jack, which if left out needs to be replaced by a jumper.  I don't remember exactly where the jumper would go, but it's pretty obvious from the schematic.  If that jack is not wired properly or jumpered correctly, then the LFO will fail to modulate the delay even if the circuit is calibrated perfectly.  If  you get any sort of sweep from the LFO, that's not your problem.

[daverdave]

nah I've wired in the expression jack, the pedal works, it flanges. It needs calibrating, I couldn't get a decent sound sorted when I tried today, but I just didn't have the patience. I'm pretty sure it's working ok though. I'm not sure how to get it sounding perfect, but it is flanging. I reckon I need to spend some time messing around with the trimmers to get it going properly.

[eurekaiv]

Gonna bump this post as my trouble seems similar but the calibration process isn't discovering anything.  I've built one of the last SAD1024 Boards to Rev 3 spec and I've got signal passing through but no flanging. I can very faintly here some sweep in the background if I stop playing anything at all and adjusting the rate makes it speed up and slow down but like I said, it's really really faint.  All my voltages seem to be ok compared to the schematic though its possible I missed something there I suppose. I tried doing the no scope calibration test as noted in a post above but turning TR1 either passes un-effected signal and then cuts the signal out completely at the very end of its range. All necessary jumpers are in place based on the build docs.   

In case it helps my SAD1024 Voltages are below.  Pin 9 seems suspect as it's connected to bias (15V) through a 1k resistor but is reading .2.  I imagine it should be up closer to 15V no?  Do I have a bad SAD1024?
1. 0
2. 13.1
3. 7.5
4. 0
5. 3.76
6. 15
7. 15
8. 7.57
9. .2
10. 7.38
11. 15
12. 3.71
13. 0
14. 7.57
15. 13.1
16. 0

[oldschoolanalog]

Pin 9 should read 14V. Check R16, R18 & C12.
Do this first, as there is something very wrong there.
Also, Pins 2 & 15 look way high. My unit reads ~6.7V. Adjust TR1 to bring this V down.

Do I have a bad SAD1024?
Don't assume that yet. First see what's up with Pin 9.
Then we'll take it from there.
Dave

[eurekaiv]

Thought so... I checked R16 last night but it seems fine.  I'll look at R18 and C12 this evening.  Thanks!

[eurekaiv]

Well, the voltages on the SAD are fine.  I forgot to solder pin 9!     The pads are so small I looked right past it probably a dozen times.  Anyway, the symptoms are still the same.  No flanging but passes signal.  The rate knob creates a faint motorboating sound when full up and there is some faint thermin-ish type sounds when the trim pots are just right... mostly when adjusting TR3.  About to go and write down voltages for all my ICs to see if I can't locate a problem in any of them.

[eurekaiv]

Ok, I know I'm talking to myself here but I found an open resistor on the bias.  R6 I think it was...  I've got flanging now.  Tricky getting the trimmers right but i've got it sounding pretty good. 

[oldschoolanalog]