01-18-2008, 03:18 PM
Hi all,
I recently found a very nice Philco 20 De Luxe with the bird's eye maple arch, and just starting the process of doing the chassis.
On a preliminary inspection, and familiarization of the circuit, I found the output trans to have one side of the center tap open, The other side had 322 Ohms.
http://www.nostalgiaair.org/PagesByModel...029582.pdf
I decided to disassemble the trans hoping it was a broken wire at the inside terminal. No luck.
I then prodded around the top layer of windings and still did not find any continuity. I then cut a little of the top layer off, went to the second layer, carefullt scraped about 2 turns of wire, I got a reading of 316 Ohms.
Soldered a thin wire to the winding, then added back the heavier lead to the terminal, added the insulation, and a little JB welld for stability, and reassembled the trans.
My question is, will the difference on 6 ohms make any difference in the operation fo the push pull output? I say no, but want to make sure. I suspect there is enough vairence in other parts to make this 6 ohms not matter at all, except maybe on a scope under test conditions
.
The second question on this model is what is the voltage rating on the filter caps? I suspect that the 630v caps we use will work fine. It does seem odd to have such a large filter can to hold such small vaule caps.
There are two 1uf caps, a 1.5uf, and a 1.3uf. I have not taken the can off yet to see if there is room in the can for the replacements. I don't want to empty the can, but want the underside to look original. The chassis has never been worked on before.
Thanks in advance, and take care,
Gary [Image: http://www.grabbittradios.com/radio/emoticon.gif]
[Image: http://www.grabbittradios.com/radio/transrep1.jpg]
[Image: http://www.grabbittradios.com/radio/transrep2.jpg]
[Image: http://www.grabbittradios.com/radio/transrep3.jpg]
[Image: http://www.grabbittradios.com/radio/transrep4.jpg]
I recently found a very nice Philco 20 De Luxe with the bird's eye maple arch, and just starting the process of doing the chassis.
On a preliminary inspection, and familiarization of the circuit, I found the output trans to have one side of the center tap open, The other side had 322 Ohms.
http://www.nostalgiaair.org/PagesByModel...029582.pdf
I decided to disassemble the trans hoping it was a broken wire at the inside terminal. No luck.
I then prodded around the top layer of windings and still did not find any continuity. I then cut a little of the top layer off, went to the second layer, carefullt scraped about 2 turns of wire, I got a reading of 316 Ohms.
Soldered a thin wire to the winding, then added back the heavier lead to the terminal, added the insulation, and a little JB welld for stability, and reassembled the trans.
My question is, will the difference on 6 ohms make any difference in the operation fo the push pull output? I say no, but want to make sure. I suspect there is enough vairence in other parts to make this 6 ohms not matter at all, except maybe on a scope under test conditions
.The second question on this model is what is the voltage rating on the filter caps? I suspect that the 630v caps we use will work fine. It does seem odd to have such a large filter can to hold such small vaule caps.
There are two 1uf caps, a 1.5uf, and a 1.3uf. I have not taken the can off yet to see if there is room in the can for the replacements. I don't want to empty the can, but want the underside to look original. The chassis has never been worked on before.
Thanks in advance, and take care,
Gary [Image: http://www.grabbittradios.com/radio/emoticon.gif]
[Image: http://www.grabbittradios.com/radio/transrep1.jpg]
[Image: http://www.grabbittradios.com/radio/transrep2.jpg]
[Image: http://www.grabbittradios.com/radio/transrep3.jpg]
[Image: http://www.grabbittradios.com/radio/transrep4.jpg]
