06-09-2023, 06:51 PM
Hi -
I picked up a Philco Predicta Decorator several months ago. Since then I have been working on it spontaneously. It has been completely worked through: paper caps replaced, resistors replaced as needed, re-coated flyback, etc. I've been gradually working through the plethora of issues commonly associated with these sets, but I am stumped on one in particular.
The set suddenly lost its raster. The horizontal output tube briefly red-plated. Noticing the red-plating, I turned the set-off and let it sit for around a month before returning to it. Upon returning to it, I carefully turned the set on. The horizontal output tube didn't red-plate, but the raster was still absent. I used an oscilloscope to check out the signals from the grid of the horizontal output tube, grids of the horizontal mult, and both sides of the AFC diodes. Everything seems to be normal. In addition to this, the flyback tests good, and I can hear the high voltage. Immediately after pressing the power button to turn the set-off, the raster briefly reappears and collapses as normal.
This problem appeared in the past but seems to be intermittent. When the raster was present, the horizontal wouldn't lock. I feel it may be a problem in the damper section, but I don't really trust my judgment at this point.
Any ideas would be greatly appreciated!
Cheers!
- Hayden
I picked up a Philco Predicta Decorator several months ago. Since then I have been working on it spontaneously. It has been completely worked through: paper caps replaced, resistors replaced as needed, re-coated flyback, etc. I've been gradually working through the plethora of issues commonly associated with these sets, but I am stumped on one in particular.
The set suddenly lost its raster. The horizontal output tube briefly red-plated. Noticing the red-plating, I turned the set-off and let it sit for around a month before returning to it. Upon returning to it, I carefully turned the set on. The horizontal output tube didn't red-plate, but the raster was still absent. I used an oscilloscope to check out the signals from the grid of the horizontal output tube, grids of the horizontal mult, and both sides of the AFC diodes. Everything seems to be normal. In addition to this, the flyback tests good, and I can hear the high voltage. Immediately after pressing the power button to turn the set-off, the raster briefly reappears and collapses as normal.
This problem appeared in the past but seems to be intermittent. When the raster was present, the horizontal wouldn't lock. I feel it may be a problem in the damper section, but I don't really trust my judgment at this point.
Any ideas would be greatly appreciated!
Cheers!
- Hayden
