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|5/6/2000 2:29 PM|
|CJ Landry||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.
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
Thanks for any input,
|CJ Landry Anybody, got any ideas on my origin... -- 5/8/2000 12:54 PM|