MarkC Posted May 23, 2017 Report Share Posted May 23, 2017 Hello, I am considering adding a DC speed control to my Nagra 4.2 power supply, which is -30v, so that I can speed up or slow down when rewinding. I am not sure which pins to connect for power. Could someone please advise me. Thank you in advance MarkC Quote Link to comment Share on other sites More sharing options...
Jim Rillie Posted May 23, 2017 Report Share Posted May 23, 2017 I couldn't leave this alone any longer. Is this possible, or damaging? maybe what is required is "To boldly go where no man has gone before" credit: Star Trek original intro VO by actor William Shatner from NDG, who knows how to use his voice. Quote Link to comment Share on other sites More sharing options...
mikewest Posted May 24, 2017 Report Share Posted May 24, 2017 The speed correction terminal is for use with the QSV accessory which allows the tape speed on playback to to varied by plus or minus 12% The QSV is a complex LC network and pin 4 will not control rewind speed. Do not apply any voltage to pin 4 otherwise smoke and malfunction are likely! mike Quote Link to comment Share on other sites More sharing options...
Philip Perkins Posted May 24, 2017 Report Share Posted May 24, 2017 The late Harvey Warnke made me a custom Nagra playback speed control to work with his TC mod of the IV-S....I need to find out what I did with it. It was how we were able to fine tune playback speed to follow film from cameras with wonky motor crystals. The thing saved a lot of asses in the late '80s and early '90s. As I recall he used a 20-turn pot to get fine enough control. Quote Link to comment Share on other sites More sharing options...
MarkC Posted May 24, 2017 Author Report Share Posted May 24, 2017 Thanks for the replies. It seems to be a dangerous experiment. I certainly don't want to destroy the Nagra. Thanks Mike, do you know if the rewind speed is connected to the voltage of the power supply? I mean my 12v is much slower than my other 18v so I thought increasing to 30v would speed up even more. From what I can gather pin 5 is right but no idea which other pin or pins, maybe the battery pins? Hi Philip, I would love to see that you end up finding it, sounds very interesting Quote Link to comment Share on other sites More sharing options...
mikewest Posted May 24, 2017 Report Share Posted May 24, 2017 Hi Mark From memory the supply voltage affects the rewind speed So if you are on batteries it's slower and if you use the Nagra power supply (30v) the rewind is certainly faster And yes pin 5 is the power input mike Quote Link to comment Share on other sites More sharing options...
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