05-26-2017, 10:35 AM
Currently repairing a model 70 , pre B220000, ( determined this, thanks to Ron's explanation on Philco's numbering system). Problem: can only receive one very strong station.
Originally I did not get any signal but located an open primary winding of 1st Detector coil (6). Re- wound the coil. Now I only receive the strongest local station on the correct dial frequency. Checked voltages at the RF, a 24 tube. Found screen voltage high (120v), schematic called for around 90v. Checked resistance at the long tubular resistor and fond it had changed values. Corrected the voltage to the screen voltage (now 90) with another resistor. Still no change. Checked RF coil windings and they are correct.
I ordered a new 24 just to eliminate it, although I think the current one is good but can't verify it.
Question 1. While checking the long tubular resistances I compared the current ohms readings to the Resistor data sheet and I find them way off. Has anyone found the schematic to be wrong?
Question 2. Has anyone encountered the same problem and found the solution to only receiving one strong station and nothing else?
Question 3. Can anyone offer any suggestions as to a repair
I am still new to this forum and very grateful for all of the wonderful posting on this forum. I look forward to your comments. A special thanks to Ron for all of his input and expertise.
Originally I did not get any signal but located an open primary winding of 1st Detector coil (6). Re- wound the coil. Now I only receive the strongest local station on the correct dial frequency. Checked voltages at the RF, a 24 tube. Found screen voltage high (120v), schematic called for around 90v. Checked resistance at the long tubular resistor and fond it had changed values. Corrected the voltage to the screen voltage (now 90) with another resistor. Still no change. Checked RF coil windings and they are correct.
I ordered a new 24 just to eliminate it, although I think the current one is good but can't verify it.
Question 1. While checking the long tubular resistances I compared the current ohms readings to the Resistor data sheet and I find them way off. Has anyone found the schematic to be wrong?
Question 2. Has anyone encountered the same problem and found the solution to only receiving one strong station and nothing else?
Question 3. Can anyone offer any suggestions as to a repair
I am still new to this forum and very grateful for all of the wonderful posting on this forum. I look forward to your comments. A special thanks to Ron for all of his input and expertise.
