02-22-2014, 01:45 PM
I spent a couple of hours doing some careful checks. The cap in question on the tuner has a fiber washer under the other washer. I did some voltage checks on the 1st det and the osc tubes. I can PM with everything if needed, but the most obvious 'oddity' is the voltage on the cathode of the 24 1st det tube. When the radio is in the good part of the range, where it picks up, the voltage sits about 8v. I can adj the dial from 55 up to where it cuts out - same, that is, until I hit the place where it goes bad - then the voltage jumps up to 12v, and climbs to 24v as I tune all the way up, drop back, it falls until it hits the working part, then stabilizes at 8v again.
Now ... the odd part. I found if I turn the volume down until I can barely hear, I can get solid tuning up all the way to the top! It's when I start to turn up the volume, when I hit a point, it begins to oscillate and cuts off. The voltage on the cathode of the 24 also jumps at the point it begins to oscillate (and becomes microphonic). If I turn back down, it clears up. Also, the higher I turn the volume, the lower the freq that it starts to mess up.
I swapped the 27 with very little change (I am still waiting for my new one to show up). When I swap the 24 with a new one, the point I can turn up the volume lowers. I tried a weak 24, and couldnt get anything but static. I double checked the coils in the circuit. Also resistors, which are a little off, but not a lot. Also have voltages from the bias resistor. So, somehow, the volume control (checked also) and tuner and this problem are connected. I also want to comment that this is the area where a cap (#12 see my 2nd pic in the thread- I believe it may be mislabeled as #5) was replaced - years ago in looking at the style, so I believe this problem has been with this radio for quite some time - maybe even since new. This one has me scratching my head... got to be some dumb, simple thing I am overlooking. Any thoughts?
Sorry for the "book" ... just hoping someone can help me solve this mystery.
Now ... the odd part. I found if I turn the volume down until I can barely hear, I can get solid tuning up all the way to the top! It's when I start to turn up the volume, when I hit a point, it begins to oscillate and cuts off. The voltage on the cathode of the 24 also jumps at the point it begins to oscillate (and becomes microphonic). If I turn back down, it clears up. Also, the higher I turn the volume, the lower the freq that it starts to mess up.
I swapped the 27 with very little change (I am still waiting for my new one to show up). When I swap the 24 with a new one, the point I can turn up the volume lowers. I tried a weak 24, and couldnt get anything but static. I double checked the coils in the circuit. Also resistors, which are a little off, but not a lot. Also have voltages from the bias resistor. So, somehow, the volume control (checked also) and tuner and this problem are connected. I also want to comment that this is the area where a cap (#12 see my 2nd pic in the thread- I believe it may be mislabeled as #5) was replaced - years ago in looking at the style, so I believe this problem has been with this radio for quite some time - maybe even since new. This one has me scratching my head... got to be some dumb, simple thing I am overlooking. Any thoughts?
Sorry for the "book" ... just hoping someone can help me solve this mystery.
If I could find the place called "Somewhere", I could find "Anything"
Tim
Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44
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