[morzh]

Yep that's the one.

[morzh]

Greg

Couple of questions, if you don't mind.

1. The minuses of the electrolytics seem to be tacked to the chassis. Which makes no sense as they also go to the common B- which is separate from the chassis. Are they in fact tacked or is it an optical illusion on the photo?

2. The bottom dogbone resistor, Brown and Grey and Black dot, is missing, and so is the Red and White with Black dot.
Could you tell me where on the sockets do they connect? Are they the R8 and R7 on the sch I pointed to?

http://www.nostalgiaair.org/Resources/772/M0021772.htm


PS. Yes the R8 in my radio is simp!y shorted (pins 4 and 5 of the 35W4) and so is the R7. The latter is not likely to affect much, the former....possible, though don't see how. If it is part of filtering, the value is low.

PPS. The C3 is 47nF vs 20nF in the sch. Not sure what it is there for. Bypassing the diode....why?

[gregb]

1. The minus of the e-caps connects to pin 1 of the 35W4 tube, which is just a tie point for the B- circuit.

2. The Brown Grey black dot resistor is connected between pin 4 with one side of the line cord and pin 5 and 6 which are jumpered together.

3. The red white and black dot is actually orange white and black. It is connected from pin 3 of the 35W4 to pin 3 of the 50B5 output tube. Yes they appear to be R7 and R8

Let Me know if you need anything more.

Gregb

[gregb]

This is the first time I have ever looked at this radio and while I am in there I thought I better check a few things. The small resisters were way out of tolerance so I changed them for new ones. There was one original cap still in it as well so out it will go. The radio works ok with a good antenna connected but it is noisy. No hum to speak of, no worse than most any other simple radio but it picks up the plasma TV upstairs and the fluorescent lights are very noticeable.
Reception on my outside is very acceptable.

Gregb

[morzh]

Greg

the two resistors I can see, likely R5 and R6, the vertical "GBY" and "RRG", I couldn't quite get their values from the code, they should be 220K and 330K, were really out of tolerance, especially the GBY which I think measured as 1M+, and 220K was 360K. I paralleled them with some resistors to bring them into compliance but was not sure in teh first place of values and if the radio is 100% compliant with the sch. R9 (Brown-Red-Red body) measures as 1.2K (correct) though says in the sch it is 2.2K.

Also there are some discrepancies, as I said - the R7 and R8 are missing, and so are C5 and R6, plus the outputs 5 and 6 of the 12AT6 are shorted and the R2 is missing as well. The R4 was replaced by Kirk or someone else to 6.8M (is 10M by the sch) which is OK, does not matter much. This is the one I replaced with 100K right now to bring down the hum. The radio looks exactly the same, all the parts and the chassis are, even those 220K and 330K resistors and the IF transformer look the same.

Also the antenna coil hookup is just a smidge different.

But then again, our radios are Sterlings and the sch from the Teletone. Close but not exactly the same. Yours is closer.

[Arran]

Looks like another postwar startup brand that assembled it's chassis using cheap surplus parts, it's a wonder that they didn't use a few Micamolds or a wet electrolytic whilst they were at it.
 I have another critter like that, it's called a "Medco" made by a short lived company calling itself "Telesonic", they produced maybe three or four models between 1946 and 48 and then shut their doors. Someone on the alternative forum scanned a Sams folder for me  for it but their example and mine are not quite the same as the position of two of the tubes were swapped. It also doesn't help that someone decided to try turning the radio into a tube amp (I think) got confused, and then abandoned the project. I think that what confused them is that the set used a fixed bias supply and generated that voltage by tapping it out of the B- side of the power supply like a pre war AC radio, very strange.
Regards
Arran

[morzh]

   



Yesterday I spent some time trying to tinker with C3 and introduce the R8. No result, same thing.
The last thing I did, I ordered 12AT6 and 50B5 on eBay, they are cheap, I got 8 NIB AT6 for 8 bucks and the 50B5 for under 5 bucks, also NIB. I wasn't able to change these as I do not have them. 50C5 I have which is exact same tube as 50B5 has a different pinout. There was something about RCA not being able to pass some safety with it and the pinout change did it. Kirk sent me some tubes but not these.

So if THIS does not work (not sure why it would but have to try, nothing else is left)....screw it, the 100K R4 seem to almost do the trick - the stations stay good and the hum goes down about 10dB.

[Arran]

Mike;
  As you well know the 50B5 came out first, and then after a few years was replaced by the 50C5. Someone on the alternative forum said that the reason for the change was due to the fact that if one plugged the wrong tube, like a 12BA6, into the 50B5 socket that it would cause something to be energized. In any event it seems that they stopped using the 50B5 in new sets around 1950-51, though they kept making them as replacements for at least a decade after that. The two tubes are not interchangeable although on can rewire the socket to make it work, which I did a few times when I did not have a 50B5 on hand.
Regards
Arran

[morzh]

I ordered one, there are plenty of NOS on the Bay, and fairly cheap too.

[morzh]

Well....the 12AT6 came last week and the 50B5 came today, after, according o the seller, having first returned back for invalid address.
To add to that, the tube was supposed to be a Philco.

That one.

http://www.ebay.com/itm/262788004817?_tr...EBIDX%3AIT

If you look, this below is the same photo, but says the different tube.

http://www.ebay.com/itm/Philco-6S4A-Elec...2788004817

In fact he has bunch of Philc tubes listed with the same exact photo.


What came is an RCA in the RCA box. I am not even sure the glass marking is the same in the picturre.
But it is a 50B5 and tests as it should.

Anyway, the hum diminishes just a smidge after changing 12AT6 and I am not even sure it is not a wishful thinking at play.
Went through the chassis....no non-conformances present.
I decided to throw in the towel. It works, with that resistor decreasedbit doesn't hum too bad, so....

[OldRestorer]

Throw in the towel?
Hmmmmmm...
I'm gonna throw a towel at your head,
I told you 2 weeks ago, If it is playing nice and the hum is not bad then be done with it...

[morzh]

Well....I wanted to take the last shot at it. After all I did not change all tubes before, I just tested them.