Philco 70 restoration attempt - singing now.
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I am in the middle of rebuilding the bakelite blocks in my 70. Do I read correctly that you are leaving them soldered in, and only cutting the small wires going the the cap, pushing out, then installing new caps with the block still in the radio? I have unsoldered the ones I have done so far, but I needed to check the resistors and replace the power cord.
Also, what do your resistors check coming off the # 34 block? In case my location numbers are off, this is the next block up from the filter caps, .01, and connects to the 47 tube. There are 2 resistors that are identical, 35 & 32 (Riders) and 33.
I also wondered what you were doing with 2 electrolytics in your filter cans? I understand they are series, one looks like an 8mf. Curious about that one.
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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Tim
No, I do not desolder backelites. No need. You only need to do it if the wires short and rigid and do not allow for the cap to turn when you need to extract the old and put in the new caps.
According to marking on the resistors and the sch the 33 rsistor is 100K. The other two are 250K. All were off.
(This post was last modified: 02-08-2014, 02:49 PM by morzh.)
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Tom
Thanks a bunch, the panel and the tube came today, got installed and the schematic for the 47 has been recreated.
Will try to power up tomorrow, though...first the tube test. Also tomorrow.
PS. While writing to Tom I realize I am yet to reinstall the tuning cap back so the power-up is probably gonna happen Thursday the earliest.
(This post was last modified: 02-10-2014, 09:42 PM by morzh.)
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Mike, if you get a chance, I'd sure like to see a shot or two of your completed electrolytics, and how you reassembled them.
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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Tim
The shots I posted are what I have. Basically other than gluing the cylinder back to the base this is about it.
I could get more shots tonight and then post them. The caps were not original though, they were Cornell-Dubilier labelled.
Look at the cap I had in 90 (page 2 of the post, it is on the next page of this Philco Restoration topic), you have pretty much the same type in yours.
This looks closer than what I have in my 70.
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OK, it is singing now.
Today I installed the tuning cap. This was a bit of an adventure as someone not only replaced the grommets with some pieces of felt but also removed the metal spacers.
The spacers were a challenge - Home depot had babkas for everything, Lowes had grommets and washers (I have to install some extra rubber washers as the grommets though fit fine are a little short height-wise), but no spacers. Eventually I bought what they call a tension pin, which is pretty much a tube cut legthwise (I do not need the cut but this is the closest thing they got). It is also 2" long. So I had to use Dremel and cutting stone and cut three pieces out of it, and then grind off the excess and imperfections.
Also while the external diameter of the tube is a bit larger (still fits inside the grommet), internal proved to be a bit tight for the screw to go through (I thought I measured it against the screw I had with me but I did not insert it fully). So I first took the screw, put the metal washer on, and then forced the screw by, well, screwing it into the newly made spacers. I counted on the fact that once inserted it would become whole and act as a screw so I will be able to secure the cap, which I did just fine.
Anyways, measured the AC volts, then checked for shorts, then applied the voltage via a Variac, heard the buzz when touching grids on detector and some RF tubes.
Rotated the tuning gang ang got my local station.
The very first song - "The whiter shade of pale".
BTW the speaker seems to be in original condition and very clean, and the transformer is original also.
It sounds OK. I guess I will be experimenting with the detector same way I did with he 90.
OK, will keep listening to it tonight, tomorrow or during the weekend - alignment.
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OK, noticed that the transformer is buzzing. As if it was not compressed right. Tried to tighten the two screws, but no effect. Not sure what that could be. A loose E-piece in the core?
It does not heat up much, and if it were a short turn it would screw up all voltages plus I'd probably see some smoke by now.
Not a reason for me to change it right now but.....I should expect some very low hum, but not really buzzing.
Now, knobs: I did not pay attention during the purchase but I have only one big rosette and then two small handles same as the power handle or a volume handle in 20. They are all Philco knobs but still....
They all should be rosettes except the power, right?
(This post was last modified: 02-14-2014, 06:53 PM by morzh.)
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Did the alignment a couple of hours ago.
Wow.....this thing is sen-see-teeeve, with 2 feet of wire for aerial it pulls in tons of stations, every 2-3 degrees of rotation pull another one.
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1. Listening to it more I realized that the distortion similar to 90 and 20 is still there, just less pronounced, but recognizeable.
I am not willing to mod the detector - the radio will loose quite a bit of sensitivity. I compared it to the 90 - right now it is lot more sensitive.
2. Alluvasudden when turning it on I did not hear the transformer buzz. Then after 10 minutes I heard a little. So I decided to experiment: plugged it into the Variac and set the volts to 110V. When the voltage remains under 115V there is no buzz. But as son as it reaches 117-118V I hear the buzz and at 120V it is quirte pronounced. Even though I do not think it should buzz at 120V all the more reason to install buck transformer.
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Well,,,I have different idea about the voltage buzz,,,,I would install a power resistor to drop the voltage down to 115 volts,,,the transformer would really like that,,,no --need to make it over work,,and run hot ,,,will run the same ,,,I do this ,,to almost all radio's of old time----just my 2 cents----CHEERS
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