Need help with a zero point dd

[ravendark]

I am having trouble with my zero point dd. I am only getting the dry signal in the output. I used an audio probe and I can get the delay signal from both pt2399s and I know for certain that the tl072 is good. I also replaced the dpdt switch just to be sure that the switch was good. I am all out of ideas on what could be causing the issue. Any help would be much appreciated. Thanks in advance!

[selfdestroyer]

I am having trouble with my zero point dd. I am only getting the dry signal in the output. I used an audio probe and I can get the delay signal from both pt2399s and I know for certain that the tl072 is good. I also replaced the dpdt switch just to be sure that the switch was good. I am all out of ideas on what could be causing the issue. Any help would be much appreciated. Thanks in advance!

Just looking at the schematic, are you getting any audio on pin 7 of you TL072? If not, work your way backwards on the schematic with your audio probe. Toss some voltages up and a few pictures if this does not help. Hope you get it going.

Cody

[ravendark]

I am getting audio from pin 7 on the TL072, but it is the dry signal with no repeats.
Here are the voltages I am getting from the chips
TL072
Pin3 and 5- 4V
pin 2- 3.6V
Pt2399
pin 1- 4.9V
pin 6- 2.4V
I am not sure what other pins I should take readings off of.

and some pics
http://i357.photobucket.com/albums/oo13/whamola_man/zpdd%20back_zpsgkro2rak.jpg

http://i357.photobucket.com/albums/oo13/whamola_man/zpdd%20front_zpswi4k9s3i.jpg

[selfdestroyer]

I am getting audio from pin 7 on the TL072, but it is the dry signal with no repeats.
Here are the voltages I am getting from the chips
TL072
Pin3 and 5- 4V
pin 2- 3.6V
Pt2399
pin 1- 4.9V
pin 6- 2.4V
I am not sure what other pins I should take readings off of.

and some pics
http://i357.photobucket.com/albums/oo13/whamola_man/zpdd%20back_zpsgkro2rak.jpg

http://i357.photobucket.com/albums/oo13/whamola_man/zpdd%20front_zpswi4k9s3i.jpg

Nothing jumping out at me with your pictures. What about Q1 & Q2, what are the voltages of them? When you said you were gettting delayed output on the PT2399, was that from all the output pins (9, 12, 14, 15) ?

Cody

[ravendark]

I am getting audio from pin 7 on the TL072, but it is the dry signal with no repeats.
Here are the voltages I am getting from the chips
TL072
Pin3 and 5- 4V
pin 2- 3.6V
Pt2399
pin 1- 4.9V
pin 6- 2.4V
I am not sure what other pins I should take readings off of.

and some pics
http://i357.photobucket.com/albums/oo13/whamola_man/zpdd%20back_zpsgkro2rak.jpg

http://i357.photobucket.com/albums/oo13/whamola_man/zpdd%20front_zpswi4k9s3i.jpg

Nothing jumping out at me with your pictures. What about Q1 & Q2, what are the voltages of them? When you said you were gettting delayed output on the PT2399, was that from all the output pins (9, 12, 14, 15) ?

Cody

I am getting audio from pins 9, 12, 14, and 15 on the pt2399s.
and the voltages on Q1 and Q2 are 0.05V on the collector, 0.6V on the base and 2.3V on the emitter.

Thanks for helping me out!     I really appreciate it!

[mgwhit]

I am getting audio from pins 9, 12, 14, and 15 on the pt2399s.

If you are getting repeats on those pins on IC3, then your 90% of the way home.  It's just a matter of tracing the audio back out through the Mix pot to the second TL072 op amp.

Test at R20, C20, lugs 2 & 3 of the Mix pot, C23 and R24.  From R24 on, any signal should be making it back out with your dry signal.

[ravendark]

I am getting audio from pins 9, 12, 14, and 15 on the pt2399s.

If you are getting repeats on those pins on IC3, then your 90% of the way home.  It's just a matter of tracing the audio back out through the Mix pot to the second TL072 op amp.

Test at R20, C20, lugs 2 & 3 of the Mix pot, C23 and R24.  From R24 on, any signal should be making it back out with your dry signal.

I can trace the audio through the mix pot to R24. the signal volume is really low coming out of R24 but it seems to be there. I tried touching up the solder joints on those resistors and caps to no avail. I think I might try and replace R24 tomorrow to be on the safe side.
The TL072 seems to be fine. (at least I would assume that it is since I get an output even if it is only the dry signal)

[mgwhit]

Yeah, the voltages you posted on your ICs look okay.  Note sure about the transistor voltages, but they look believable.

Are you getting repeats at R24 or just more dry signal?  You may get a little dry signal along that path way, but should should be listening for repeats.  If there are no repeats along that pathway I outlined then you'll need to start nitpicking everything.  And just for giggles, are you getting repeats on R14?

[mgwhit]

I tried touching up the solder joints on those resistors and caps to no avail. I think I might try and replace R24 tomorrow to be on the safe side.

At the risk of sounding harsh, your soldering on that board is pretty rough.  There are a lot of joints that look dull rather than shiny (check out that huge one right in the middle, probably one leg of C6) and many that look like the solder just rode the lead up through the hole rather than bonding to the pad.  Make sure you are touching the pad and the lead simultaneously with the iron.  When you reflow, add a little fresh solder to kickstart the process (unless the pad is already swimming in it).

[ravendark]

[/quote]

At the risk of sounding harsh, your soldering on that board is pretty rough.  There are a lot of joints that look dull rather than shiny (check out that huge one right in the middle, probably one leg of C6) and many that look like the solder just rode the lead up through the hole rather than bonding to the pad.  Make sure you are touching the pad and the lead simultaneously with the iron.  When you reflow, add a little fresh solder to kickstart the process (unless the pad is already swimming in it).
[/quote]

Its not harsh. Its the truth. That board was definitely not my best solder job. Thanks for the feedback. 

On the plus side I found the problem and took care of it. The switch was killing the wet signal, so I put in a couple of jumpers and... viola! It lives.

Thanks for all the help!!

[mgwhit]

Cool!  Glad you found it.