AD3208 snafu, ISO a tip or two

[rufustf]

I researched the previous posts and didn't find any that adressed this particular glitch so here goes.
Finished the AD3208, put it in the box, the light goes on, but the signal is un-effected. Absolutely no difference in sound when on or in bypass. Checked voltages at IC's, all okay. Checked transistor voltages, also okay. Checked the connections at the DC jack (I have a 9v battery wired through a stereo input jack and a DC jack w/ a ring disconnector) and the + & - appear to have a short. Looked everywhere on the board w/ a meter, everything looks okay, no solder blobs or other suspect connections. (Due to the complexity of this circuit I was super anal when putting parts on the board, hoping to avoid this sort of thing). I don't have a scope or a meter with the diode tester, though the diodes appear to be okay and are properly oriented, as are the caps, IC's, and transistors. I suspect a bad cap mabye but I don't know how to test them, on or off the board. I've built a bunch of effects before and thought I was getting pretty good at it, but this complicated circuit has me buffaloed. (It's complicated to me, at least).
Any troubleshooting tip is appriciated.
Thanks in advance-
Jason

[puretube]

dunno the schem of it,
but if the light goes on, there`s probably no short on the power rails.

when bypassed sounds exactly like "on", re-check your switch-wiring  :?:

[rufustf]

It uses the millenium bypass, and the LED is wired to the board, not the switch. The schematic, etc. is at generalguitargadgets.com. I'm sure it's not the switch, I disconnected the board from the switch and I got a  bypass/no signal switch. The short at the dc jack seems to be the clue, but if I knew for sure I wouldn't be here asking for tips.
Thanks again-
Jason

[puretube]

once again (I`m not gonna search for schems - I`ve done that all my life...):
If there is a (dead-) short on the DC-jack: nothing that depends on being fed from that power source will ever work: no light, no mill. byp., no effect.

Or maybe I just don`t understand what the problem is...  :?

[puretube]

...if a circuit doesn`t work properly, the schem is of interest...
if a pedal worx in bypass, but not when on, the offboard wiring is of interest, too...

[EDIT] maybe this helps:
http://www.generalguitargadgets.com/diagrams/ad3208_schematic.pdf

[george]

have you twiddled the bias trimmers on the BBDs as per Scott Schwartz's build notes on www.generalguitargadgets.com?

This needs to be set correctly or the BBDs won't pass signal

[Fret Wire]

Hi, if you use the detective work on this link, it will speed up the troubleshooting.
http://diystompboxes.com/sboxforum/viewtopic.php?t=29816

[puretube]

have you twiddled the bias trimmers on the BBDs as per Scott Schwartz's build notes on www.generalguitargadgets.com?

This needs to be set correctly or the BBDs won't pass signal

...in the case described above, the sound stays unaltered in ON-mode and in BYPASS-mode, which will never happen with signal going thru a couple of BBDs (mis-biased or not) - so I come to the conclusion, that probably both modes play the original dry signal without going thru the delay...

[rufustf]

Oops, hadn't noticed the finer points of the build notes, think I'll get started on that! Thanks Pure Tube, Fret Wire, & George for taking the time to post a reply. I'll post another when I get the thing up and running.
Jason

[george]

have you twiddled the bias trimmers on the BBDs as per Scott Schwartz's build notes on www.generalguitargadgets.com?

This needs to be set correctly or the BBDs won't pass signal

...in the case described above, the sound stays unaltered in ON-mode and in BYPASS-mode, which will never happen with signal going thru a couple of BBDs (mis-biased or not) - so I come to the conclusion, that probably both modes play the original dry signal without going thru the delay...

I don't understand ... the BBDs WON'T pass signal if they are misbiased (badly enough), so how can it be "going thru" them?

[puretube]

plz re-read that statement thoroughly  :wink: ;

my conclusion is, that the bypass circuitry of the pedal
is alway in bypass mode - no matter how the BP-switch is thrown.

(becoz the sound surely would be different, if the signal indeed would go thru the BBDs - especially when those are misbiased - especially when misbiased to the point where they don`t pass anything anymore...)

[Connoisseur of Distortion]

maybe you have some sort of mechanical error... as in your switch?  :?

[puretube]

he uses the mill.-byp...
*something* seems to be conducting the clean signal to the output-jack
(while seemingly not being processed by the BBD/filter circuit).

This doesn`t mean, that the delay portion of the pedal *doesn`t* work...

[george]

plz re-read that statement thoroughly  :wink: ;

my conclusion is, that the bypass circuitry of the pedal
is alway in bypass mode - no matter how the BP-switch is thrown.

(becoz the sound surely would be different, if the signal indeed would go thru the BBDs - especially when those are misbiased - especially when misbiased to the point where they don`t pass anything anymore...)

fair enough puretube - sorry to misunderstand you!

I know with my AD-3208 the effected sound DOES sound different, even with the delay level turned all the way down!  In a good way! In fact it's made me think of building a buffer into the output of the Shaka Tube which comes before it ...!

[rufustf]

Well, here's a new development. Although I haven't used the scope yet (my friend has it & I think he's still out of town) the unit now behaves differently. It makes the guitar about four times louder than when bypassed.
Tried tweaking the trimmers. I got a whining noise when I set the 1M trimmer too high, a bit past midway seems to be the "silent" point. I am assuming the noise is "clock" noise.
Adjusting the other 4 trimmers didn't do anything. I couldn't even dial in a little "slap-back" delay.
Would it be of help for me to post the voltages on the pins of the IC's and transistors? It's an awfully complicated thing, so I hope posting all of that won't be like trying to explain how to tie a double windsor over the phone, but if that would aid any of you helpful folks I'll certainly do it.
Again, thanks, this forum is just the best.
Jason

[puretube]

at least, we can assume, that the bypass-switching does work now...
(i.e.: when switched to: effect ON, the signal indeed does go through the active delay circuit, and not straight from inputjack to outputjack...)

[puretube]

pin-out-arrrghh... :roll:

http://diystompboxes.com/sboxforum/viewtopic.php?t=33655