10-08-2014, 03:29 PM
Well, if Kirk wants to give me one of his two PT-69 sets, I won't argue! 
But back to the subject at hand...
Success!
[Image: http://www.philcoradio.com/images/phorum...e00020.jpg]
[Image: http://www.philcoradio.com/images/phorum...e00021.jpg]
I finished rewiring, recapping, and recarbing last night. However, the thing refused to work.
Today, I pulled out the trusty ol' tube tester. Would you believe both of the XXL tubes were dead? They still light up but test dead. Fortunately I had several extras, and replaced them both.
Then I tried it again...still nothing.
I took some voltage readings, and found no voltage at the plate of the 1st IF amplifier tube, a 7B7. Aha
Turned it off, pulled the plug, and did a resistance test. Sure enough, the primary of the 2nd IF amplifier was open. Notice the IF transformer lying in front of the working chassis in the first photo above? That's the culprit.
I found a prewar Philco 455 kc IF transformer in a box I have of parts which were pulled from dead Philco chassis. It isn't exactly the same as the original - the original only had one adjustment screw, while the replacement has two.
I replaced the wires to this transformer, installed it in the set, and tried it again.
Woo hoo, it is working...
[Image: http://www.philcoradio.com/images/phorum...e00022.jpg]
The under-chassis view as things now stand. Since the original electrolytics were long gone and I did not have any suitably sized cardboard tubes, I just installed the new electrolytics in the manner shown.
Notice I am using a piece of wire coiled up as a temporary loop. With the move last year, I can't seem to find the original loop antenna - or the escutcheon and dial scale for the cabinet!
At some time in the past, the original tone control was replaced with a control that includes a switch which is being used for power. The original off-on switch was the first button on the pushbutton assembly. The wires to that switch are cut off. The switch probably failed, and the repairman replaced the tone control with one that includes a switch rather than trying to fix the pushbutton switch. I'll look into that issue later. I know just what to do to fix it, as I've done it before...
But back to the subject at hand...
Success!
[Image: http://www.philcoradio.com/images/phorum...e00020.jpg]
[Image: http://www.philcoradio.com/images/phorum...e00021.jpg]
I finished rewiring, recapping, and recarbing last night. However, the thing refused to work.
Today, I pulled out the trusty ol' tube tester. Would you believe both of the XXL tubes were dead? They still light up but test dead. Fortunately I had several extras, and replaced them both.
Then I tried it again...still nothing.
I took some voltage readings, and found no voltage at the plate of the 1st IF amplifier tube, a 7B7. Aha
Turned it off, pulled the plug, and did a resistance test. Sure enough, the primary of the 2nd IF amplifier was open. Notice the IF transformer lying in front of the working chassis in the first photo above? That's the culprit.
I found a prewar Philco 455 kc IF transformer in a box I have of parts which were pulled from dead Philco chassis. It isn't exactly the same as the original - the original only had one adjustment screw, while the replacement has two.
I replaced the wires to this transformer, installed it in the set, and tried it again.
Woo hoo, it is working...
[Image: http://www.philcoradio.com/images/phorum...e00022.jpg]
The under-chassis view as things now stand. Since the original electrolytics were long gone and I did not have any suitably sized cardboard tubes, I just installed the new electrolytics in the manner shown.
Notice I am using a piece of wire coiled up as a temporary loop. With the move last year, I can't seem to find the original loop antenna - or the escutcheon and dial scale for the cabinet!
At some time in the past, the original tone control was replaced with a control that includes a switch which is being used for power. The original off-on switch was the first button on the pushbutton assembly. The wires to that switch are cut off. The switch probably failed, and the repairman replaced the tone control with one that includes a switch rather than trying to fix the pushbutton switch. I'll look into that issue later. I know just what to do to fix it, as I've done it before...
--
Ron Ramirez
Ferdinand IN
