[captainclock1988]

Hello everyone, tomorrow morning I will be acquring a 1936 RCA 5T Tombstone Radio that the cabinet is in really nice shape yet but the radio's functionality is unknown as the original cord is no longer in good enough condition to plug in and I'm assuming the usual bad caps and possibly some bad resistors, I'm getting it from someone local through Facebook market place, and they originally wanted $115 dollars and I got them down to $65 after I explained to them that the radio was going to need more than just a new power cord to get it up and running again (and that I wasn't just going to use it as a shelf queen which is what they were trying to sell it as).

Is there anything about this radio in particular that I should look out for when repairing this radio?

Pictures to come tomorrow when I pick the set up.

Thanks for your help.

-Levi

[Arran]

Like any RCA from that era check over the power transformer, they don't fail all the time, but it isn't unknown either. They also used some rubber/gutta percha wire under the chassis, so that may need replacing, as well as a candohm power resistor riveted to the chassis. I also make a point not ti make offers on a set before looking at it in person, unless it's very cheap, I would look over the chassis good, and give it a good sniff, before handing over the money, unless you have an opportunity to ohm out the power transformer. The two plate pins on the rectifier tube socket are connected to either outside leg of the HV winding, a measurement between each of those, and the chassis, will tell if it's good or not, the difference should not be more then about 20 ohms between each pin and the chassis.
Regards
Arran

[captainclock1988]

I picked the unit up, and it looks pretty clean the cabinet is even really decent. 

The radio is missing a 75 tube and had a 45 tube in place of the 80 Rectifier tube for some reason, which may have been why the radio didn't work right, (kind of like how my Philco 116 when I got it had a rectifier tube in place of one of the IF tubes).

Pictures below.

[Arran]

I can't see any obvious signs of transformer failure from the pictures, such as oozing tar, or burned looking wires, it would also smell bad. It's still worth checking before you spend time swapping out capacitors, resistors, and the like, and easy to do with a type #80 socket, the two small pins are the plate connections, large ones are for the filament. The chassis looks fairly clear, and not much tampering, if you would like to take a stab at restuffing paper caps this would be a good candidate, they are fairly easy to take apart, even compared to an Aerovox. The cabinet was refinished at some point, it looks like one of those stain and varnish combo finishes, I hope it isn't poly and stain!
  You were wondering about performance, well it isn't going to measure up to a model 16 Philco, but the 5T5 I had, (Canadian version) wasn't bad for a five tuber, reasonably selective, and sensitive once I fixed the antenna coil primary.
Regards
Arran

[captainclock1988]

I can't see any obvious signs of transformer failure from the pictures, such as oozing tar, or burned looking wires, it would also smell bad. It's still worth checking before you spend time swapping out capacitors, resistors, and the like, and easy to do with a type #80 socket, the two small pins are the plate connections, large ones are for the filament. The chassis looks fairly clear, and not much tampering, if you would like to take a stab at restuffing paper caps this would be a good candidate, they are fairly easy to take apart, even compared to an Aerovox. The cabinet was refinished at some point, it looks like one of those stain and varnish combo finishes, I hope it isn't poly and stain!
  You were wondering about performance, well it isn't going to measure up to a model 16 Philco, but the 5T5 I had, (Canadian version) wasn't bad for a five tuber, reasonably selective, and sensitive once I fixed the antenna coil primary.
Regards
Arran

Hi Arran, I've already tested the transformer, and it tested good, (I had continuity on the High Voltage winding and on the filiment winding of the 80 Rectifier tube socket). 

As far as the cabinet being refinished goes, I'm assuming this would of been finished with lacquer Toner like the Philco 116B I have would of been?

Also do you know why someone would of put a 45 tube in the 80 rectifier tube soocket on this radio? AFAIK the 45 tube would NOT be a substitute for the 80 rectifier tube.

I take it that the picture below is what the finish on this radio would of originally looked like?

[Image: https://www.radiomuseum.org/images/model..._front.jpg]

[Arran]

Yes the cabinet would have looked much like the one in the photo I think, and finished with tinted lacquer, the 5T5 I had was in a long box mantle style cabinet with the speaker at one end so it a little different. Make sure you find a photo of an original cabinet to go by, there are a lot of pictures of refinished sets online, and some people took creative license with the colours.
  I have no idea why someone would put a #45 in there other then it also has four pins, and the socket was empty. Just out of curiosity you should test the #45 to see if it's any good, I found a 2A3 and a #45 stuffed in my RCA Radiola 18 I got a few years back, both were fine even though one was in the #71A socket. With regard to testing the H.V winding, it may have continuity, but does the resistance measure the same between each plate pin, on the #80 socket, and the chassis? if it does then the transformer is probably fine, as long as the primary winding is good.
Regards
Arran

[MrFixr55]

Hi Arran, 
I know some time has gone by since your post but for $65 you scored.  I have a 5T7, similar chassis to yours but has octal tubes , all metal.  Mine was a gift from another collector for fixing his dad's PT94.  Mine had a bad transformer, but I scored a good replacement on ePay.

One easy trick after measuring voltages and leakage is to  run it with all the tubes out.  the transformer should not get overly warm.  Mine would burn if touched.

Best Regards, 

John "MrFixr"

[captainclock1988]

Hi john, actually you got the wrong person, it was me who bought the radio, not Arran, Arran was just helping me figure out the ins and outs of this radio. 

Thanks for your kind words! 


-Levi

[captainclock1988]

OK so I had a chance to dig a little more into this radio and unfortunately the high voltage winding on the power transformer on this radio was open. And I forgot to mention that the previous owner of this radio said that this  radio blew the breaker when it was powered on, which I'm assuming can be attributed to an open HV Winding on the power transformer?

[Arran]

No, popping the breaker would be caused by excessive load, or a dead short, and open winding would not do it, if it is open.
Regards
Arran

[captainclock1988]

Hmm, ok. 

The weird thing was that the way the power cord was wired up on this radio when I got it was that the power cord was wired up to the two terminals on the power switch that the power transformer's primary winding was wired to, which made the radio stay on all the time and wasn't able to be turned off with the power switch. 

There are 3 terminals of which one of those 3 terminals is listed as a "dummy terminal" on the service manual, which that one is the one that is supposed to share one of the power cord connections and one of the power transformer primary connections, and the other two terminals are for the other PT Primary connection and Power Cord connection respectively, but I'm not sure if its wired up correctly or not, as the power switch illustration and wiring diagram doesn't match the physical switch on the actual unit itself.

[Dan Walker]

I have seen a couple of radios where someone had put in a 45 tube where the 80 should be.
 On  one of those occasions   I asked the seller why that tube was in there and he told me that is where it belongs, because it fits.
 There are a lot of people out there that do not have a clue about how anything works, or how it goes together.
 It is not good but the bad part of it is,     these people raise their children the same way.
 Dan in Calgary

[Arran]

Maybe someone connected the power cord wrong? I will have to look at the circuit diagram, but popping a breaker straight away tells me that there is a dead short across the power line.
Regards
Arran

[captainclock1988]

Hi Arran, that's what I was thinking, but wasn't sure, because like I said it's hard to tell on the Riders diagram how the switch is supposed to be wired up.

I actually just received several volumes of original Riders so I'm going to take a look at those and see what those look like.

[mikethedruid]

Captain, I just sent you an email through this site with my actual email address. I have all the service bulletins for the RCA radios from the 1930s up to WW2. I'll send you an attachment with the pertinent volume if you email me at my address so I can send it to you. I cannot do attachments through this site.