[OldRestorer]

Have no idea what the heck is going on but you are doing great Mike!

[morzh]

I took my son to Liberty Science center today, so after I came back I only was able to pot the tone control which I restuffed yesterday and will put it back.
Tomorrow if I have any juice left in me (work recently just sucks me dry....and not due to the work load, if you catch my drift), I will try the power-up.

[morzh]

Well. Hit a bit of a snag. Was about to power up, but then I wanted to use the second peaker I had I thought was fully working (the one in the cabinet has he trnsformer shot). When I bought the second speaker the transformer showed half the primary open, but then when I went to investigate it showed the winding being OK so I used it to test my 90.
Now that I retested it before powering it showed the open again and this time it id not come back.
The cord is OK and the problem traces to the transforme pin. I will try to open it and see if it is a simple case of a broken wire. Otherwise will have to replace it with 1:100 pushpull transformer.

[morzh]

Took the xfmr apart....as I suspected, it was not butn, it was rotting wires.

One wire that did connect was on its last leg and as soon as i mived it it separated from the lug.
The on that did not connect at all, when I peeled the paper layers, I saw the winding wire where it soldered to the lead wire broken off the winding and green.

Well, no sense trying to tackle this one.

The transformer is large and probably universal p-p and SE, as it is assmbled with all Es packed together And all Is together. This is probably why it si so heavy, 1-1/4 lbs.
A p-p only should be less.

The problem I am having is the hole space makes 125C the only one fitting and it is a bit smaller than I think I need though current wise for 45 tubes it is adequate and can handle 8W of power / 60mA of current.
It is model H speaker.

The xfmr is model 2848-J, the info is missing at Chuck's but I suspect it hould be the same as in 20 or 2x45 90, part number 2766 with 100:1 or close ratio.

Anyone ever replaced this one? What did you use?

[morzh]

OK, some good news.

I decided to take another look at the speaker that came with the radio.
Well, the field coil was bad, but the transformer is OK.
So I have just performed the graft. everything buzzes like it should, 3.1k for field and 250-250 centertap to primary ends.

Tonight when my CPR provider comes back home from work I will try to power up.



PS. More bad news. Before power-up I decided to check the phase inverter, the interstage transformer. Well, half the secondary is open. This won't allow me to make that mod where I disconnect primary and use secondary for inversion.
PPS. A little good news - I got a bit apprehensive about coils, so checked every coil....All are OK.

so I need an interstage....90 has the same I think, or 20 possibly.

[morzh]

Well, yesterday I assembled the transformer.
Had to use two pieces of wood epoxied between the clamshells, the new transformer being smaller (half size).
I riveted the transformer to the bottom plate and put the shell over, then soldered it in place.

Today turned it on....heard nothing, touched the audio preamp, got the buzz.
Measured voltages, got no plate on the 1st IF. I knew I checked coils so 2 minutes later fond a broken wire, fixed it.

Long story short, it is playing my local station.

I am questioning the decision to buy 124B vs A as it brings up the lows and seems like it is a bit much for the speaker. Mostly OK though.

The sensitivity is not great; I am attributing that to alignment that is yet to be performed.
Although my other radios were quite sensitive without it. And I am using 6" wire for an antenna. Again this usually was enough.

Tomorrow will align.

[codefox1]

You are having a lot of fun, keep going!

[jerryhawthorne]

Hang in there Mike, you will overcome! I guess I was lucky on mine, good iron all the way around. We need a picture when your done.
Best, Jerry

[morzh]

Well, I am not going to get another transformer for another $25 just to try it, let alone the fact that the clamshell bend tabs will not withstand another unbending and bending (and they are a b..tch to unbend - the thickness is such that it warped the plate and it is a 1mm thick steel).
I hope the cabinet will help some too.

All plate voltages are within 10V from the target, which I attribute to the usual modern meter upgain.

Another thing (to be expected) - seems like changing Osc 27 tube always trows off the frequency a little, so I guess alignment should be performed with the tube one likes the most being in the Oscillator emploi.

Oh...and the volume pot although does change the volume, never brings it close to zero on the local station which may or may not be OK given the fact the wiper never really touches the "D" voltage - there is 70K resistor there. But one thing I have not checked is the volume pot resistance, probably should just in case.

[morzh]

Q1. Does anyone know where the trimmer location chart could be found?
The one in Riders is for some similar chassis but not the same - the tubes shown are different. And trimmers' positions not quite the same.

Q2. Is alignment performed with tubes shield installed or not?

[morzh]

Another snag.

The volume pot is in a sorriest of shapes.
It was behaving funny, making noises, producing hum, and being 800k end to end.
The wiper was giving me many megohms in the middle.

I took it out, opened it (easy) and lightly cleaned it. It became almost fully open after that. The resistive path was probably next to open and one swipe of alohol moistened qtip did it in all the way.
I do not think a pencil rub is a good solution.

Well, will need a 500K taper.

[jerryhawthorne]

Mike, if it wasn't for your bad luck, you would have no luck at all!
Jerry

[morzh]

Well, some good luck....maybe.
Found a NOS Mallory taper 600-something kOhm I bought some 1-1/2 years ago while repairing the Westinghouse . I think it will do just fine. The shaft is "biteable", universal long aluminum shaft.
Tomorrow.

Jerry, what did you use for alignment (meaning chassis trimmer diagram)?

[OldRestorer]

You are a good little worker bee Mike,

SOme pictures would definitely help though,

[morzh]

Will put them either tonight or tomorrow. i have them, just been busy.

BTW "Aligning Philco Receivers" book by Rider gives the same trimmer positions on p.9.
http://www.silverslingshot.com/PDFFILES/...s_1937.pdf
(if it opens but does not display - just save it and open with Acrobat reader).
What gives?

Ron, maybe you know?