I swapped around the 6BA6's and R37 still got smoking hot. Also, C4 seems fine. Very confusing....

Possibles, the grid leak is open, which is why I check resistors as I replace caps. If the tube itself has no issues and the grid is coupled to a plate, even that of its own. Then it is highly likely the cap is leaking. The cathode is going open (resistor / backbias if it has one), the cathode would be going highly positive (almost B+) relative to chassis if a cathode resistor is involved.

Marc

What value does R1 (1 megohm per schematic) read?

Also the voltages you read with the tube out seem high. Check the value of R23 in the power supply filter section. Is it shorted? The side of R23 connected to C50B is supposed to be at 250VDC. You showed 320-327VDC
Much too high!
The 6BA6 tube is rated at a maximum plate voltage of 330VDC so you need to find out why the 250 Volt supply is so high!

Corby

Either a tube is gassy or positive voltage is connected to the AVC line. Which side of R1 has the highest positive voltage? This will determine if it's the RF 6BA6 or somewhere else down the line. Even if a grid resistor is open voltage should not be that positive unless the tube is bad.

Shouldn't be much connected to pin #1 but may need to lift wires to see when voltage is no longer positive?

I have not looked at the circuit but if B+ is going high something is not conducting. If all grids are going positive I would be looking at the circuit of the centre tap.

Marc

Something is definitely amiss somewhere . Voltage at pin 8 of the rectifier tube is reading about 460, it should be about 350. I'm going back over all the connections I've made, comparing them with photos I took before I began to recap the set and so far everything looks ok. As for R23 I replaced it when I re-caped the set, I used a resistor of the correct value (1400 ohm, 10watt overkill is good)...I've got to get this set to function, it's very important to me.

Thanks for all the advice !

Diagram says 330 on load so you actually need to find out where B+ has gone open starting at R23 , the resistor/s may be burning, or have due to over voltage now that a critical one has gone open. You can get shorts on switches and on IF cans if deteriorated wires have cut through on the chassis, in this case it is more likely the primary shorted by solder or miswired. A Mica could also have shorted (& new caps can fail).

Marc

The schematic shows 5 Ohms for the Power TX primary. Is it OK? I'm not sure if a primary can short in such a way as to increase the output voltage but that might be the problem. Not sure how to verify that type of TX fault? Maybe pull the rectifier tube and feed a 5VAC into the filament winding and see what you get across the primary. Also a good idea would be to run the radio from a variac and adjust the variac for the 350V out of the rectifier. Then see if the radio operates like it should!
Corby
Got to thinking, measure the 5 volts at the rectifier tube filaments. If it reads too high (over 6 volts according to your measurements) then the TX is bad.

The best way of testing the transformer without frying things is to pull the rectifier, you can then measure it's AC output voltage. A 5Y3 offload will surge to close to twice EMF, that is normal & why I am pedantic about not using underated caps on B+. 500V is closer to what many sets used.

You can use resistors to load it, but they need some attitude as they will get hot.

Marc

Hi

Is the meter set on DC volts? Reading DC on AC scale can give a much higher reading.

Your radio can not operate with that positive of grid voltage. It has to be zero or negative with a signal being received.

Wholly concur with Norm. Something is radically wrong. Clearly all or part of the B+ is open circuit . The highest consumer of current is the output tubes. So I would surmise that them getting no voltage would send B+ sky high.

Check the wiring to that part of the circuit, make absolutely sure that the Out put tubes are geting power.. As I said I am suspicious that the HV is what is overloading the resistor. If you have been through the set, there is absolutely every chance that you could have miswired,& the OP transformer is not wired in.

We can all make mistakes.

Marc

Primary of power transformer tests good, And both of the high voltage leads out of the transformer read 350 volts AC. Admittedly, that is 25 volts higher than the schematic says, but the line voltage at my house is sometimes on the high side. I know how handy they are, but I haven't (yet) purchased a variac.

@ Corby.... R1 reads 1.8 M....That's nearly double the resistance it's supposed to have. I pulled the tube but didn't disconnect the resistor to test it. I'm still struggling with how to determine which resistors need to have one end disconnected from the circuit for testing.

Thanks again for all the advice. I'm determined to hear this Airline play again !...Even if it kills me

There are some devices where there are no tappings to make provision for voltage fluctuations and that can impinge on the behaviour of the device. and stress components.

Many pieces of equimpent of US & European origin end up here. They have a bad habit of being 220V transformers with no correction. Due to circumstances prevailing at the time, the bulk mains Radio's here could be adjusted from 200 -260VAC . The Mains here normally hovers around 240 - 250V .

I have a Heatkit IT-22 in at the moment. The Magic eye resistor has been adjusted to 3.75 Meg, but that is marginal, so to function properly this will need to be run from the Variac or a step down transformer.

The B+ could be reduced by adding more resistance ahead of R23 if the sec. AC output proves high due to mains However,, a variac providing the correct input is preferrable, As you cannot determine the reason B+ is high, due to the set is not functioning properly.

Marc

You can read a resistor in-circuit... if the reading is normal value or HIGH... it is believable and probably an accurate reading. So If it reads high you can trust the reading and replace the resistor.

But... if it reads low you'll need to lift one end and re-test it..

The theory or reasoning... is that there is nothing in a circuit that might be in parallel with a resistor that could ever increase the value.
However ANYTHING/everything (conductive) in circuit that is in parallel with a resistor WILL always lower its value.

Just a sanity check, (for my sanity! ) what does the 5V filament voltage read on the rectifier tube?

Corby

Corby,

With the tube out I get 5.7 ac volts...Tube in it fluctuates wildly.

The above readings were chassis to heater. just measuring across the heater, tube in socket I read 5.3 volts. Which is what one would want

Be careful how you go about working with An 80 / 5Y3. The filaments sag and the manufacturers tell you that; There is only one orientation where it can be run sideways.

If you are measuring the filament with the tube side ways the fluctuations may be due to "flashover". Get a good one of those & it will blow the filament apart. The problem that appears to be with this set at the moment, is not so much a short circuit but a long one. You need to find out where the voltage has stopped going to and that is probably where the fault is.

I have seen wires soldered into a terminal, insulation on, and of course the standard factory one of not soldering the joint at all.

Marc

Your member location shows central California. I'm in Lompoc CA. Is that close to you?

Corby