Thanks Hesener, I've had enough practice at this little project of yours, Joachim's and FDW's.
If your going to build something it's worth while doing it right.
https://live.staticflickr.com/7848/33434148568_3fe86dcd5b_k.jpg
If your going to build something it's worth while doing it right.
https://live.staticflickr.com/7848/33434148568_3fe86dcd5b_k.jpg
Stick a10k across input and ground them adjust the central trimpot until you measure 0.0mv across the input. Then measure the rest of it.
I have a known good, separate, shunt reg pcb that I wire up for all my builds so I can check the riaa section. It means I can rule out any faults in the shunt.
I also put the last transistor on each side of the input stage on header pins, then you can swap them easily to adjust the offset before soldering them in.
I have a known good, separate, shunt reg pcb that I wire up for all my builds so I can check the riaa section. It means I can rule out any faults in the shunt.
I also put the last transistor on each side of the input stage on header pins, then you can swap them easily to adjust the offset before soldering them in.
Next issue - I hate this project 🤬
when I connect the cart and the power amp, boards are running wild.
Voltage on the outputs directly hits 14V and - 10V.
do I have an issue with grounding?
what has to be connected to central GND:
Cheers
Stephan
when I connect the cart and the power amp, boards are running wild.
Voltage on the outputs directly hits 14V and - 10V.
do I have an issue with grounding?
what has to be connected to central GND:
- GND from both inputs
- resistors from the impedance selectors
- GND from both outputs
Cheers
Stephan
Ah, I always float my sockets so the outer isn't in electrical contact with the chassis. Only mix signal gnd and psu 0v where I want. Which is normally in the psu.
I use a 4 core cable between psu and paradise boxes. +/-/0v and 4th wire for chassis gnd on paradise back to psu 0v star via a DDRC. Tonearm earth goes into isolated socket via 3 position switch, with floating, signal gnd or psu/chassis gnd as the 3 switch positions. That accommodates all possible deck/ tonearm wiring earth setups. Signal gnd is usually the quietest, but I've built patadises where it wasn't due to tonearm wiring.
I use a 4 core cable between psu and paradise boxes. +/-/0v and 4th wire for chassis gnd on paradise back to psu 0v star via a DDRC. Tonearm earth goes into isolated socket via 3 position switch, with floating, signal gnd or psu/chassis gnd as the 3 switch positions. That accommodates all possible deck/ tonearm wiring earth setups. Signal gnd is usually the quietest, but I've built patadises where it wasn't due to tonearm wiring.
I usually don't form a common bond between input and output socket signal gnd either. It's only a small loop, but it's a loop.
The loading resistor can be soldered to the spare set of input holes on the pcb, or wired onto an extra rca socket and soldered into an rca plug. Check you have no continuity between rca gnd and chassis on all sockets.
The loading resistor can be soldered to the spare set of input holes on the pcb, or wired onto an extra rca socket and soldered into an rca plug. Check you have no continuity between rca gnd and chassis on all sockets.