07-03-2013, 09:46 PM
Hi guys,
I first want to thank you all for help with the electrolytic re-stuffing and that stand alone value for the .5mf metal box I had asked about several weeks ago. Now I was lucky with that AA5 and Philco 38-93 I did about 6 months ago. After a quick parts swap both radio's started singing and still do. Well I guess I am not so luck with this one. I double checked all my values that replaced the old parts (Capacitors and Electrolytics). The Resistors are within tolerance. I know I have everything wired right from what I can tell, but I can't seem to get the radio to play.
Let me give you a little history in past trouble shooting for this set: The first time I turned on the set before restoration I got nothing after several on and off switching I did receive several stations (I thought I reformed the restored electrolytics (Sometime in the 80's) that caused it to come to life. So it did work before restoration and I did take several of the voltage readings and they seemed to be good on the RF, Det Osc, and IF stages. After restoration I got nothing on a first fire up and then after turning it on the second time I did get several stations but they would disappear and then come back every once in a while. Now I don't get anything but static and crackles as well as pops.
I did test all the tubes and replaced several tubes that had slow cathode heating. I know the audio output is working because I get feed back when I put my finger over the grip cap. But I do not get any sort of station when I put my finger over the other grid caps. Right after restoration if I put my finger over the Det Osc. I did receive stations, but when I took my finger off it dissipated to nothing again.
I did several Tube socket data readings specifically on the R.F., Det OSC, and I.F. The filament voltages on AC for all three were right around 6.20 when the chart on the schematic calls for 6.3v. The Plate Volts were all in the ball park of 245.8v DC plus or minus a few. The chart calls for 245 to 255v DC.
Now what is strange: the Screen Grid volts for the R.F and Det Osc. measure at 79.5 and 75.1 Volts DC and the chart calls for 90v. The I.F. Screen grid volts reading with the tube in the socket reads -78.9 and calls for 90v on the chart. Could this be my problem? I am quite lost and this is my first time trouble shooting a radio at this depth. I know the coils in these early Philco's are known to go open. Any help and guidance would be great, I really would like to get this set going. It is a Code 121 single speaker cathedral model.
Thanks guys, the chart I am talking about is here on nostalgia air.
http://www.nostalgiaair.org/Resources/646/M0029646.htm
I first want to thank you all for help with the electrolytic re-stuffing and that stand alone value for the .5mf metal box I had asked about several weeks ago. Now I was lucky with that AA5 and Philco 38-93 I did about 6 months ago. After a quick parts swap both radio's started singing and still do. Well I guess I am not so luck with this one. I double checked all my values that replaced the old parts (Capacitors and Electrolytics). The Resistors are within tolerance. I know I have everything wired right from what I can tell, but I can't seem to get the radio to play.
Let me give you a little history in past trouble shooting for this set: The first time I turned on the set before restoration I got nothing after several on and off switching I did receive several stations (I thought I reformed the restored electrolytics (Sometime in the 80's) that caused it to come to life. So it did work before restoration and I did take several of the voltage readings and they seemed to be good on the RF, Det Osc, and IF stages. After restoration I got nothing on a first fire up and then after turning it on the second time I did get several stations but they would disappear and then come back every once in a while. Now I don't get anything but static and crackles as well as pops.
I did test all the tubes and replaced several tubes that had slow cathode heating. I know the audio output is working because I get feed back when I put my finger over the grip cap. But I do not get any sort of station when I put my finger over the other grid caps. Right after restoration if I put my finger over the Det Osc. I did receive stations, but when I took my finger off it dissipated to nothing again.
I did several Tube socket data readings specifically on the R.F., Det OSC, and I.F. The filament voltages on AC for all three were right around 6.20 when the chart on the schematic calls for 6.3v. The Plate Volts were all in the ball park of 245.8v DC plus or minus a few. The chart calls for 245 to 255v DC.
Now what is strange: the Screen Grid volts for the R.F and Det Osc. measure at 79.5 and 75.1 Volts DC and the chart calls for 90v. The I.F. Screen grid volts reading with the tube in the socket reads -78.9 and calls for 90v on the chart. Could this be my problem? I am quite lost and this is my first time trouble shooting a radio at this depth. I know the coils in these early Philco's are known to go open. Any help and guidance would be great, I really would like to get this set going. It is a Code 121 single speaker cathedral model.
Thanks guys, the chart I am talking about is here on nostalgia air.
http://www.nostalgiaair.org/Resources/646/M0029646.htm
