MSefi.com read only forum (Jan.15,2018)

Dear All,
After completing construction of my V3 MS, i found my VR circuit wouldn't work. After much gnashing of
teeth and careful study of the circuit, I found that my pots R52 and R56 work in reverse i.e. they both need to be
turned fully CLOCKWISE. The pots are inserted in the board correctly according to the white printed legend. Just
writing this in case anyone has the same problem. Anyone else found this?

Dave.

Usually that happens when the pots are in backwards, though you may have some kind of substitute pots in there that put the knob at the other end (which would make the "correct" installation backwards). It's not a big deal, as long as you remember they're backwards.

I do have the same issue, because I use the Falling edge trigger (Swaped VR Sensor Wires).
So I have to adjust the R56 Pot clockwise to get trigger at 0V.
But, I am confused the R52 function now, since the adjustment did not show difference in my scope.
I may have to check if my R52 is still good, but I am also wondering if Turning R52 "Clockwise" still can reduce the effects of noise?

teng169 wrote:I do have the same issue, because I use the Falling edge trigger (Swaped VR Sensor Wires).
So I have to adjust the R56 Pot clockwise to get trigger at 0V.
But, I am confused the R52 function now, since the adjustment did not show difference in my scope.
I may have to check if my R52 is still good, but I am also wondering if Turning R52 "Clockwise" still can reduce the effects of noise?

What sort of input signal are you testing it with? It's very unlikely that the R52 circuit would be non-functional.

I am running 12-1 missing tooth VR with MSII-EXtra on V3.75 SMD board.
Below is the scope image when I turning R52 either CW or CCW, when the R56 is tunned at near 0V tirgger point.




Before, I turned the R56 CCW, and get the bleow image.


I will do a systemative experience again tomorrow with more recording.

Thanks in advance.