ampage
Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

 
Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
  View Thread

Help with NE570 + a new schematic online

5/6/2000 2:29 PM
CJ Landry
email
Help with NE570 + a new schematic online
I wanted to repost this so it does not get lost at the bottom of the list.  
 
Thanks again for any input. Schematic link is at the bottom.  
CJ  
 
 
I am starting to fix pedals that have been laying around forever and I ran into a problem with one I am not too familiar with.  
 
I am working on a Digitech PDS 1002 that has no delayed output. The clean signal is present.  
I have traced the problem to the NE570 stage which filters the delayed signal from the digital portion of the circuit. I can see the signal at the output of the Compander which feeds the input of the digital portion. Then I can see the chopped wave at the output of the digital portion and which is input to the 2nd stage of the NE570 which I believe is configured as an Expandor.  
 
Now the problem is I do not see anything at the output of this stage (pin 7). However, there is a dc level present at the output but no signal. Pin 5 (INV pin) is at 1.8v which is Vref. but no signal.  
Following this is a filter circuit and there is nothing at the emitter of this transistor. I have swapped the IC out with 4 different ones so I know the chip is good.  
 
One question I have is the Crect (pin 1 and 16) of the NE570. The 2nd stage has a control circuit that connects to this pin. What does this do?  
 
Also, I will be posting the schematic for this pedal at my web site so we can all be on the same wave length. please check it out at  
http://www.compassnet.com/~cjlandry/schems/schemdir.html  
 
Thanks for any input,  
CJ Landry

 
Replies:
CJ Landry Anybody, got any ideas on my origin... -- 5/8/2000 12:54 PM