1935 GE Model A-53 AM/SW Tombstone Radio

[old_coot88]

Originally Posted by DavGoodlin

I had a look at the schematic and the 5000 ohm volume control seems to vary suppressor grid voltage on the 6K7 IF tube.

Looks like it also ties to the cathode and to the 6A8 cathode. So applying varying positive voltage on the cathodes equates to varying neg. voltage on G1s (control grids).

[vortalexfan]

Well I'm not sure about the volume control and whether or not its original or not because its the same exact volume control pot as what's in my Philco 116B which is from 1936 and unfortunately it has developed the same "sticking" power switch issue as the power switch on my Philco 116B has.

The volume control/power switch pot on this radio is a CTS (Central Telephone System) Type T Power Switch/Volume Control Pot, which seems seems to be a trouble proned volume control/power switch pot, because actually come to think of it this humming issue is exactly what my Philco 116B did which I thought it was bad filter caps but now thinking upon it I'm now wondering if it wasn't maybe a bad volume control pot, which I'm now wondering if that's not the case here...

CTS by the way has a plant in Elkhart, Indiana which is not too far from where I live, which is actually where the two aforementioned pots were made.

[vortalexfan]

I had acquired late last year, more or less the sister set to this radio the RCA 5T and that thing when I first acquired, would blow the breaker for the circuit my workshop was on in my house, (and he told me that's all it did for him as well, and that was why he was selling it).

It was because the previous owner of the set a fellow antique radio enthusiast/collector had at one point replaced the original cloth cord with a modern lamp cord but he didn't wire it up right, which was why it was blowing the breaker, and it took me a few months of studying the Rider's Manual and the old RCA Red Book service diagrams for this radio to figure out that the wiring diagrams for the switch on this radio on those manuals (or at least the Rider's anyways) were written incorrectly and had the "dummy terminal" on the Power Switch marked in the wrong spot which is I think why the previous owner had issues with the wiring of the RCA 5T I am currently writting about.

Anyways the RCA 5T I just got going is a great performing set, its super sensitive and selective and the SW band on it picks up stations like its nobody's business (I was picking up the WWVB time stamp signal @ 5 MHz, I was picking up many Religious Stations on the SW band, and I was even picking up Radio Havanna out of Havanna, Cuba on it!

Anyways my point is that some of these old radios are super easy to repair and troubleshoot and some of these radios are a pain to troubleshoot even using the best troubleshooting skills one has to offer.

Actually calling the RCA 5T the "sister radio" to the GE A-53 is kind of inaccurate because the 5T is a vastly superior radio to the GE A-53 in many ways including the fact that the 5T has a great performing AVC circuit, whereas the GE A-53 lacks any sort of proper AVC circuit.

[vortalexfan]

A little update:

I think I may have found a replacement switch/volume control that might work on this radio, someone gave me an old junker Philco Model 60 Cathedral Radio from the same time period as this GE is from (1936) and it also had a CTS Model T power switch/volume control assembly in it, the volume control pot on this switch/volume control is a 500k Ohm (.5 Meg) pot and I was wondering if this might be a viable replacement (even though this radio's original pot was 5k ohms) would the 500k vs. 5k make that much of a difference in how this radio performs?

Any help in this matter would be appreciated.

Thanks.

[vortalexfan]

Well Unfortunately I think the radio's power transformer got fried because when I tried turning it on the pilot light wouldn't light up (the bulb is still good), and the power transformer was really hot to the touch and the Kill-a-watt meter was reading over 100 watts and the rectifier tube was the only tube that was hot to the touch, the rest of the tubes were stone cold.

So I think this radio unfortunately might be toast.

[dieseljeep]

Originally Posted by vortalexfan

A little update:

I think I may have found a replacement switch/volume control that might work on this radio, someone gave me an old junker Philco Model 60 Cathedral Radio from the same time period as this GE is from (1936) and it also had a CTS Model T power switch/volume control assembly in it, the volume control pot on this switch/volume control is a 500k Ohm (.5 Meg) pot and I was wondering if this might be a viable replacement (even though this radio's original pot was 5k ohms) would the 500k vs. 5k make that much of a difference in how this radio performs?

Any help in this matter would be appreciated.

Thanks.

The 500K pot is strictly an audio pot. It won't control the bias on those tubes.

[dieseljeep]

Originally Posted by vortalexfan

Well Unfortunately I think the radio's power transformer got fried because when I tried turning it on the pilot light wouldn't light up (the bulb is still good), and the power transformer was really hot to the touch and the Kill-a-watt meter was reading over 100 watts and the rectifier tube was the only tube that was hot to the touch, the rest of the tubes were stone cold.

So I think this radio unfortunately might be toast.

When testing a radio transformer, always remove the rectifier tube first before applying power, in case the set has a B+ short, electrolytic or other component.
Either the PT is wasted or the short was robbing the 6V heater circuit.
Try it again with the watt-watcher and the 80 tube removed.

[old_coot88]

Originally Posted by vortalexfan

...when I tried turning it on the pilot light wouldn't light up (the bulb is still good), and the power transformer was really hot to the touch....

How long was it run in that condition?

[vortalexfan]

Originally Posted by dieseljeep

When testing a radio transformer, always remove the rectifier tube first before applying power, in case the set has a B+ short, electrolytic or other component.
Either the PT is wasted or the short was robbing the 6V heater circuit.
Try it again with the watt-watcher and the 80 tube removed.

It actually has a 5Z4 rectifier tube in it, but either way, I removed that tube from the radio, plugged it in turned it on, and sure enough I heard a well pronounced sizzling noise coming from the transformer, so yes I definitely think the transformer is bad.

I have a power transformer on the Philco 60 that I could check to see if its still good or not, and if it is I might be able to swap that into this radio, because the Philco 60 is a very similar chassis design to this GE (2 band radio, AM and SW, similar tube count as well, and same tube voltages).

The the radio wasn't on that way very long, I turned it off right away as soon as I saw it wasn't working and felt that the transformer was getting hot.

what do you guys think?

[dieseljeep]

Originally Posted by vortalexfan

It actually has a 5Z4 rectifier tube in it, but either way, I removed that tube from the radio, plugged it in turned it on, and sure enough I heard a well pronounced sizzling noise coming from the transformer, so yes I definitely think the transformer is bad.

I have a power transformer on the Philco 60 that I could check to see if its still good or not, and if it is I might be able to swap that into this radio, because the Philco 60 is a very similar chassis design to this GE (2 band radio, AM and SW, similar tube count as well, and same tube voltages).

The the radio wasn't on that way very long, I turned it off right away as soon as I saw it wasn't working and felt that the transformer was getting hot.

what do you guys think?

I got lost in the dialogue!
What transformer is damaged? The one in the GE A83 or the one in the Philco?

[vortalexfan]

Originally Posted by dieseljeep

I got lost in the dialogue!
What transformer is damaged? The one in the GE A83 or the one in the Philco?

The transformer in the GE is bad, and I want to see if the transformer in the Philco will be a suitable replacement or not.

[dieseljeep]

Originally Posted by vortalexfan

The transformer in the GE is bad, and I want to see if the transformer in the Philco will be a suitable replacement or not.

I checked the schematic and the power transformer looks close!
The B+ might be a little high!
Tag the leads when disconnecting from the original chassis, as the Philco colors might be different.

[vortalexfan]

Originally Posted by dieseljeep

I checked the schematic and the power transformer looks close!
The B+ might be a little high!
Tag the leads when disconnecting from the original chassis, as the Philco colors might be different.

I'm also concerned about the fact that the Philco uses the old style tubes vs. the GE using the Octal style tubes, would that make a difference?

[dieseljeep]

Originally Posted by vortalexfan

I'm also concerned about the fact that the Philco uses the old style tubes vs. the GE using the Octal style tubes, would that make a difference?

The tubes are identical, except the base. Same heater current and voltage.
Philco didn't switch to octal base tubes until the '37 model year.

[vortalexfan]

Originally Posted by dieseljeep

The tubes are identical, except the base. Same heater current and voltage.
Philco didn't switch to octal base tubes until the '37 model year.

OK, so then the power transformer should be able to swap out for each other, the only other issue I could see being a problem is the mounting screw hole spacing for the power transformer from the Philco radio vs. the the GE's original Power Transformer.