DOD EF440 (general guitar gadgets) not woking, me = crazy

[mugan]

Help me please i'm going crazy debugging this effect !

- the project is the one from www.generalguitargadgets.com (http://www.generalguitargadgets.com/diagrams/ef440_sc.gif)

- the symptoms:
 a) very low output, i have to crank the amplyfier gain and volume all the way down to hear something, almost a farty distortion
 b) level pot is ineffective

- mods: R5 = 1 meg instead of 470k, ic = ne5532 instead of tl022, all the rest is just like the layout pic

- shorts: no (checked so many times i don't remember)

- wiring: ok (same as above)

- multimeter readings (both level and range are at max):

  battery = 8,65v

  ic:
  1= 3,98
  2= 3,86
  3= 3,24
  4= 0
  5= 2,05
  6= 2,49
  7= 1,26
  8= 8,65

  D1:
  a= 0
  k= -3,30 (don't know why but it seems to swing between -3,30 and 0, very slowly)

  D2:
  a= -3,96
  k= 1,33

  VTL led:  (swings as above)

   a= 1,27 max
   k= 0

   ldr1= 1,70 max
   ldr2= 2,00 max
   ldr3= 1,70 max

all electrolitic caps mouted correctly, i've also tried other ic's with the same result.

HELP HELP HELP HELP !!!!

[Dan N]

I don't know. I just checked mine and the voltages to pin 8= 8.8, pin 4=0, and ALL the rest were around 4.4

Why the 1M resister? Is your vactrol placed correctly?

A note, the knobs are very interactive, so if one is set out there somewhere, you may not hear any change when twiddleing the other. Also, the pot names are switched on the GGG project.

Wish I could help more. It's a proven circuit, so hang in there and good luck!

[mugan]

It's a mod on the project page:

"Modification Information from RickL:

As it is with lot of Envelope Filters it needs the sensitivity (called 'Range' on the layout) turned all the way up to get a decent sweep. I modded this for better response by adding another 470k resistor in series with R5. If you build it you might just want to use a 1M resistor for R5."

Ah, so the pots are swapped? kool...  anyway, yes the vatec is placed in right position, i've checked (i've also tried reversing it but it's the same!)

So your voltages are different, that is a starting point. Is it yours a Diy unit?

thanks for helping!

[Dan N]

Yes, mine is DIY. Recently someone posted some guts from a red unit (try a search) and I worked from that schem. It had R6 as 6K8. That may be why with 22K there you would want more drive from IC1a.

Mark Hammer posted some mods for this here. One I love is a resonance pot. I used a 100K pot in series with 400K resistance in place of R12. A nice and useful addition.

Don't expect too much when played clean. Gosling quack. Run a hot signal into it. Mine loves my Super-Fuzz!

So, blah blah. I still have not helped get yours working!

[mugan]

all sorted! It was a small track on the pcb that for some strange reason wasn't there on my board, i've connected it and now it WORKS! YES!

thanks anyway, Dan, for answering!

[Dan N]

Yay!!!

I was fooling around with mine yesterday pushing it with a LPB-1. There was a point where it would kind of stop working when boosted too much. Guess it likes a "happy medium".

Have fun!

[yonatan.cohavi]

Hey. I Know its a very very very OLD thread but I have the exact same problem can you remember where was the missing track?!??!