Hi, I recently made a PT-80 Delay from GGG (http://www.generalguitargadgets.com/effects-projects/modulationecho/pt-80-delay/) but I can't figure how to make it work properly;
I'm powering it with 18v DC bypassing the charge pump and the pcb is homemade. I checked a trillion times my connections
When in bypass mode everything is fine but when engaged I hear some serious amount of noise and the repeats are very low volume, I only noticed them with maximum delay time.
These are my readings, I already tried swapping all my ICs but the readings are the same:
TL072
Pin 1: 6V
Pin 2: 6V
Pin 3: 6V
Pin 4: 0V
Pin 5: 3V --- the main problem (I think), should be 5.5V and can't figure why it's so low, it's directly connected to Pin 3 & 6 and the resistor values are right
Pin 6: 6V
Pin 7: 6V
Pin 8: 12V
NE571N
Pin 1: starts at 0.5V then drops to 0.04V --- should be 1V
Pin 2: 1.8V
Pin 3: 1.8V
Pin 4: 0V
Pin 5: 1.8V
Pin 6: 6.62V --- slightly high, should be 6.5V
Pin 7: 6.62V --- same
Pin 8: 1.8V
Pin 9: 1.8V
Pin 10: 6.2V --- slightly high, sould be 6.0V
Pin 11: 1.76V --- every other pin is fixed at 1.8V, this one doesn't like it
Pin 12: 1.8V
Pin 13: 12V
Pin 14: 1.8V
Pin 15: 1.8V
Pin 16: 0.93V --- should be 1V
PT2399
Pin 1: 5V
Pin 2: 2.5V
Pin 3: 0V
Pin 4: 0V
Pin 5: 2.9V --- slightly high, should be 2.8V
Pin 6: 2.5V
Pin 7: 0.75V --- slightly low, should be 0.9V
Pin 8: 0.82V --- same
Pin 9: 2.5V
Pin 10: 2.5V
Pin 11: 2.5V
Pin 12: 2.5V
Pin 13: 2.5V
Pin 14: 2.5V
Pin 15: 2.5V
Pin 16: 2.5V
12V regulator
C: 18V
B: 0V
E: 12V
5V regulator
C: 18V
B: 0V
E: 5V
Pin 5 of your op amp should be at 6 volts for sure as you mentioned. pins 5, 6, 7 should all be at the same DC voltage. On the other side, 1, 2 and 3 are all at 6 volts which is expected. Focus in on this area. Are you measuring the voltages by touching the pins of the op amp or is it in a socket and you're measuring them off the socket?
It is inside a socket and I measure from the socket leads
Update:
I got a MAX1044, I powered it up with 9V and it gave a solid 14-15V on output and all the values were the same as the first post.
The weird thing is that now there is a very loud beep even in bypass mode and when I switch the pedal on, the beep boosts up to ear-rape levels. Tried again with 18V bypassing the charge pump and everything returned to the initial conditions.
Also double checked the pots, no problems.
What does it mean?