Philco 84B radio problems
 

I'm going either tomorrow or Satuday to pick up this beauty. Only cost $50.

EDIT - for information on the Philco 84B, skip down.

I was at Hamfest this morning, and I found this! A 1934 Philco 84B in beautiful condition. Best of all, It only cost me $60!

I got both of the above radios home, and much to my chagrin, they do not play. The 84 was advertised as playing but it definitely does not. I connected an antenna, and I still get nothing but a 60 cycle hum. What's going on? The 39-30 does the same thing, except it hums way louder.

Likely they have not been restored electrically. Those old caps have dried out and are no longer filtering out the hum. Also beware the 39-30 will be full of wire with crumbling hardened rubber insulation that should be replaced.

The 84 has had two capacitors replaced. The 39-30 has had the crumbled wire replaced with cloth wire and somebody in the past decided it would be a good idea to put in a 5Y3 instead of an 84. They also crossed out 84 and put in 5Y3 in the schematic. The picture is of the model 84 radio.

Tube 84 subs are 98 and 6Z4, not a 5Y3. Beware somebody might had made changes in there.
Also you should hook them up to a variac on first fire up.

After fiddling with the 84 for a while, I got some muffled scratchy sounds at the bottom of the dial, but that's it. No stations whatsoever. Does anyone have any ideas as to what might be the problem?

What kind of antenna do you have hooked up to it?

Here is my makeshift antenna.

The 2 posts on your radio, one is for the antenna, the other one is for a ground. Years ago they said to ground it to a cold water pipe or a copper rod driven into the ground. So in your instance tie both leads of that wire coil together and put it on the ANT. terminal.

That didn't do any good. It still growls like an angry cat.

Looking down at the chassis, with the controls to the front, tube in the top right corner should be a 42. Rear of chassis, from the left should be 80, 77, and 77. Check your tubes, make sure they are good.
There are 2 electrolytics in there, a 4 and 8 mfd. I assume they were replaced?

Have the black bakelite block caps been restuffed? To check unsolder one and look underneath if there is tar with OLD dust on it then it has not been restuffed.

The prices you gave for those two were quite reasonable considering the condition. What may need done is that you get a circuit schematic for each and look the wiring over real good. Philco made very good schematics with all components numbered with arrows on a component layout. That way, you can identify parts and check them off, even if you are not familiar with them.

Here's some skinny on the 84..
http://www.nostalgiaair.org/PagesByM...5/M0013875.pdf
http://www.tuberadioland.com/philco84B-early.html

The capacitor blocks have been restuffed. While I was looking in there, I found a mysterious loose/broken wire. It leads to one of the coils. Could that be a problem?

The leads you're referring to, might be item 3 on the schematic. It's just 2 wires twisted together, forming a capacitance. Usually known as a gimmick.
The circuit used is a regenerative superhet and are a little tricky to setup.

We have been discussing this radio on Philcoradio.com and have come to the conclusion that I need to check the antenna coil and oscillator coil with an ohmeter. I will also be getting rid of those dogbone resistors.

Looking at the bottom view of that chassis I see something BADLY wrong I think--I am surprised NO ONE ELSE saw it. (assuming this is the chassis for the cathedral radio).

the tube behind the power tranny, looks like a 42 does NOT seem to have ANYTHING connected to it !! a 42 is a pentode and should have at least 5-6 connections MINIMUM--and I see at most TWO. This WOULD give a no sound problem.

Not sure WHY someone unhooked the output tube--but it looks like they did.

Here is the 42 socket.

i guess that must be the 80 behind the tranny then.

I would see how my B+ looks before going much farther. Not sure exactly...but on a cold chassis like this it should be at LEAST 225, likely over 250--from the rect cathode to the filter caps. If it is that or higher--the B+ is ok.

People keep telling me about B+, but I have yet to find out what it is.

Best to check the tubes, then get a schematic and start shecking voltages.

The average tube set has two or more (lets ignore cases of more for now) power sources. The A supply is the heater voltage for the signal tubes, and the B supply is the supply voltage for the plates etc. (what the set uses to allow the tubes or transistors to process the signals). The B- terminal is often tied to chassis ground so when you measure the B+ you are measuring the B supply usually with referance to the chassis.

The letters harken from the 20's when all radios were powered by batteries. Some sets had a C- supply for the grids, but we got smart and found ways to make the B supply run the grids too. Sets with multiple heater supplies were not given any special names for the branches of the A supply, and sets that used resistive voltage dividers for multiple B+ voltages simply called the different B+ lines by their voltage.

Factory schematic and parts layout is in one of the linkys in post# 15.