Philco 15DX restoration - Printable Version
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RE: Philco 15DX restoration - Bob Andersen - 06-17-2014
The new output transformer should be here by the end of the week. Mind you I'm just going to finish it electrically. I really don't have the room or tools to repair the cabinet properly. Some day I hope to though.
RE: Philco 15DX restoration - Radioroslyn - 06-17-2014
Sounds great!! keep up the spectacular work!!
Terry
RE: Philco 15DX restoration - Bob Andersen - 06-19-2014
The new Hammond transformer arrived today
I went with the 125D because it's a perfect fit for the original mounting holes and I believe 10W should be enough. The only downside so far is that it doesn't have any spare mounting lugs for the field coils. I may end up adding a terminal strip to the wooden board.I hope to fire it up tomorrow.
[Image: https://farm4.staticflickr.com/3892/14457812291_b0632c590b_c.jpg]
RE: Philco 15DX restoration - Arran - 06-20-2014
On the schematic it looks like one side of both filed coils, #60 and #62 are tied together and connected to the blue and white wire. The other end of one filed coil #60 is connected to the center tap of the output transformer primary #58, both are connected to the green and white wire, which is connected to B+, which is also connected to the output side of the filter choke #67 and the screen grids of the power output tubes. The other end of the other field coil, #62, is connected to the blue wire, which looks like it is connected to chassis ground. The green wire and the white wire are connected from the outside legs of the output transformer primary to each plate of the power output tubes.
If you can't find a decent tie point for the blue and white and the blue leads I would add a terminal strip on one of the speaker baskets with some nuts and screws, just to make it secure, or use one of the output transformer bolts. Although it does look like the larger speaker has a terminal riveted to the basket, that would work for the blue wire. I speak about the colour code that Philco used originally, but I noticed that the Hammond transformer also has a blue wire lead along with a brown and a red one, you don't want to get those mixed up with the originals of course!!
Regards
Arran
RE: Philco 15DX restoration - Bob Andersen - 06-20-2014
Luckily there is some color left on the old wires so it wasn't too difficult to get them wired up.
[Image: https://farm3.staticflickr.com/2904/14470002505_14d5db6b60_c.jpg]
After a few hiccups like forgetting to install one of the tubes and replacing a dead #44, I was treated to booming sounds
At about 50% it starts to get painful! I'm calling the Hammond replacement a big success. Now to make it all nice and neat and install back in the cabinet...[Image: https://farm4.staticflickr.com/3887/14283423098_daeb9e62d4_c.jpg]
RE: Philco 15DX restoration - Bob Andersen - 06-21-2014
I finally broke out all my Philco globes. Sounds wonderful
[Image: https://farm4.staticflickr.com/3879/14470779685_b78c0ec324_c.jpg]
[Image: https://farm4.staticflickr.com/3903/14467420011_e7f5bb3a18_c.jpg]
[Image: https://farm4.staticflickr.com/3878/14284204818_064d5899cc_c.jpg]
RE: Philco 15DX restoration - Phlogiston - 06-21-2014
Wow! NIB tubes.
I'm just about to start on my 15X.
RE: Philco 15DX restoration - Bob Andersen - 06-21-2014
Nah, none of them are NOS - they're all used. I just had a few old boxes lying around. I wouldn't mind find some NOS Philco tubes though
RE: Philco 15DX restoration - Bob Andersen - 06-22-2014
I figured I might as well see if I can make one good output transformers from the originals. The first few pieces took some patient tapping then the rest fell out easily.
[Image: https://farm4.staticflickr.com/3886/14497968753_d13132523b_c.jpg]
RE: Philco 15DX restoration - morzh - 06-22-2014
Bob
in case you need a new one, what I did was buying a Hammond replacement and, having glued a couple of pieces of wood to keep the clamshell from collapsing, glueing the transformer to the shell and assembling it all together.
But what I realized also while bying it, was that the transformer sold by AES for 1/2 the price will work just fine. I am just stubborn enough to try to get a part that is the best, but I doubt I will hear the difference. And 20 bucks is the price of my being stubborn.
RE: Philco 15DX restoration - Bob Andersen - 06-22-2014
Here's the other one taken apart. Initially, I had some hope I could find the break in the primary but no such luck. It's many, many turns of very fine wire (40 gauge?).
This core turned out to be a little rusty too so I've got the pieces soaking in Evaporust.
[Image: https://farm6.staticflickr.com/5559/14296268179_ce8d0bbbc3_c.jpg]
RE: Philco 15DX restoration - jerryhawthorne - 06-22-2014
Bob, I will be watching this. A lot of pieces to put back together! Mike, I liked the way you handled the problem as well.
Jerry
RE: Philco 15DX restoration - morzh - 06-22-2014
If I had a winding set, I'd probably tackle it, but manually thousands of turns is too painful.
This transformer works well unde 10mA and I am not sure why Philco used this mammoth of a transformer (which did not help it) for the interstage while any 10mA half the size would do.
RE: Philco 15DX restoration - Phlogiston - 06-22-2014
Do not clean the rust off of the core. It helps provide insulation between the plates. So unless it is crumbling rust. leave it alone. If you have already cleaned the core you could paint it before reassembly. Believe it or not, a core works better if the plates are isolated. That is why it is not one large iron lump.
RE: Philco 15DX restoration - morzh - 06-22-2014
Keeps eddy currents at bay, reducing losses. But better done by using warnish (seen on new transformers).