Philco 50-701
 

I am working on my Philco 50-701 at the moment and overall it is working great but the retrace lines are a little annoying. Has anyone added retrace blanking to this model and would you be willing to share what you did?
Thanks

Gregb

Perhaps you can adapt the 19A1 Admiral retrace modification. That design has the video feed into the cathode while the grid controls brightness. http://antiqueradio.org/art/Admiral1...ingCircuit.jpg

The 50-701/2 uses the grid for video and cathode for brightness. That means you'll need a positive pulse on the cathode for blanking. Anyone try this ?

Thanks Bob, yes that is my question. I have used that circuit for my Admiral set and it works fine. Anyone know how I can modify this to work in my Philco? I have finished re-capping and a number of resistors and it works great other than the retrace lines are a little annoying. I can adjust them out but would be nice to get a little more brightness.

Gregb

You can always try a RC decade box, and try different polarities of vertical waveform different RC values, and different points in the video chain until you get it right....When a pre-designed solution is not available decade box engineering can work wonders.