1935 GE Model A-53 AM/SW Tombstone Radio

[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.

[dieseljeep]

Originally Posted by vortalexfan

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.

You might have to drill different holes to match the footprint of the replacement transformer. The original transformer is mounted a little different, with long through bolts, so it sits above the chassis.

[vortalexfan]

Originally Posted by dieseljeep

You might have to drill different holes to match the footprint of the replacement transformer. The original transformer is mounted a little different, with long through bolts, so it sits above the chassis.

Well a little update, apparently the power transformer wasn't the problem, it was the power switch on the volume control I subbed in, apparently the power switch was bad...? because I put the original volume control and power switch back into the radio last night and the radio popped right on as soon as I powered it on... Weird, I didn't know those power switches could go bad like that.

Unfortunately that persistant and untraceable hum is still there and I still cannot figure out where its coming from.

[vortalexfan]

Well for sure something's not right with this radio because the back of the radio says it's rated for 65 watts at 120 and the radio as it sits with its incessant 60 Hz hum is only 43 Watts so something's not right, either one of my filter caps failed or there's a bad tube or something else odd is going on with this radio.

I've tested all of the tubes in this radio and the 6K7 tube and the 6F6 tube both tested as having a H-K Short in it so I subbed them out with known good tubes and the hum is still there and the radio pulled the same amount of wattage, So I'm not sure what's going on with this mystery of a radio.

I'm about tempted to just salvage the bulb and tubes and capacitors out of the radio and scrap it out.

[dieseljeep]

Originally Posted by vortalexfan

Well for sure something's not right with this radio because the back of the radio says it's rated for 65 watts at 120 and the radio as it sits with its incessant 60 Hz hum is only 43 Watts so something's not right, either one of my filter caps failed or there's a bad tube or something else odd is going on with this radio.

I've tested all of the tubes in this radio and the 6K7 tube and the 6F6 tube both tested as having a H-K Short in it so I subbed them out with known good tubes and the hum is still there and the radio pulled the same amount of wattage, So I'm not sure what's going on with this mystery of a radio.

I'm about tempted to just salvage the bulb and tubes and capacitors out of the radio and scrap it out.

It depends what condition the cabinet is in! If the cabinet is in good condition, it's worth trouble-shooting a little further!
Remove all the tubes but the 6F6 and the rectifier and see if it still hums, proving it's a power supply issue. If so, bridge the electrolytics and see if it clears the hum. The power supply is a rather simple supply using a grounded B minus.

[vortalexfan]

Originally Posted by dieseljeep

It depends what condition the cabinet is in! If the cabinet is in good condition, it's worth trouble-shooting a little further!
Remove all the tubes but the 6F6 and the rectifier and see if it still hums, proving it's a power supply issue. If so, bridge the electrolytics and see if it clears the hum. The power supply is a rather simple supply using a grounded B minus.

The Cabinet is actually in pretty decent shape yet, but I did try what you suggested last night before I even saw that you suggested it, and it still has a hum, actually the hum got worse when all but the 6F6 and the 5Z4 were removed from the chassis.

I didn't try bridging the electrolytics yet, but I'm not sure what you mean by that, do you want me to bridge all of the ground connections from the electrolytics?
If so I'm not sure how I would go about doing that seeing as all of them are grounded to the chassis in some way, shape, or form so they should technically already be bridged, seeing as the chassis is the common ground in this case.

[old_coot88]

Bridging simply means "connect in parallel with", using a pair of clip leads. So bridge (jumper) each individual electrolytic (one at a time) with a single unit of equivalent or higher ratings. Note correct polarity.

The caps in question would be C19 and C20 (main power supply filters). You could jumper each with something like a 20mf 450V unit and see if it affects the hum.

EDIT. Those two caps should be replaced as a matter of course anyway. If they're the original cans they could be left in place for aesthetics, but out of circuit. There's also C26, a low voltage electrolytic across the cathode resistor of the 6F6. It won't cause a hum problem, but will cause reduced volume if it's gone open. It should be replaced anyway.