CGS67 Real Ring Modulator troubles
2010-03-27 by Guy
Hi Gain in is not used.
"Unbalance" is.
I have used germanium diodes.
All regular checks applied: shorts, polarization, etc... all seem to be ok.
Power to the chips: okay.
Continuity checks: all ok.
Socket/pot wiring: okay, I guess.
Resistor values: all ok. Output resistor: 100k.
Unbalancing makes pin 2 (of 5532) swing between app. 1.2V and -1.2V.
Resistance between the two pads on the transformers: app. .5k
Same for the outer pads of the three, and a bit less between adjacent pads of the three.
It gets weird when I hook up the module to my Serge.
To start with: pin 8 (5532) now reads app. +17V !!
None of the pots behave as I expect them to. It is as if they have a sweet spot, and only function on a very small part of the wiper trace. Once they're off that spot, the signal either gets cut off completely, or in some cases sounds like a signal being highpass filtered and then swept to zero, or something... Same with the unbalance pot. When it is at most of its trace, no signal gets through at all. At a certain point in the wiper trace, the signal "kicks in", and moving the wiper a bit doesn't do much at all.
Of note, and probably related to the high voltage at pin 8: when I move the unbalance wiper, I can see the monitoring LED of my PSU (positive rail) going much brighter, etc...
Thanks for any help or hint !
_g
"Unbalance" is.
I have used germanium diodes.
All regular checks applied: shorts, polarization, etc... all seem to be ok.
Power to the chips: okay.
Continuity checks: all ok.
Socket/pot wiring: okay, I guess.
Resistor values: all ok. Output resistor: 100k.
Unbalancing makes pin 2 (of 5532) swing between app. 1.2V and -1.2V.
Resistance between the two pads on the transformers: app. .5k
Same for the outer pads of the three, and a bit less between adjacent pads of the three.
It gets weird when I hook up the module to my Serge.
To start with: pin 8 (5532) now reads app. +17V !!
None of the pots behave as I expect them to. It is as if they have a sweet spot, and only function on a very small part of the wiper trace. Once they're off that spot, the signal either gets cut off completely, or in some cases sounds like a signal being highpass filtered and then swept to zero, or something... Same with the unbalance pot. When it is at most of its trace, no signal gets through at all. At a certain point in the wiper trace, the signal "kicks in", and moving the wiper a bit doesn't do much at all.
Of note, and probably related to the high voltage at pin 8: when I move the unbalance wiper, I can see the monitoring LED of my PSU (positive rail) going much brighter, etc...
Thanks for any help or hint !
_g