Early 1950s RCA console radio schematics

[dnewma04]

My cousin picked up a beautiful old RCA console. Unfortunately, it's missing it's field coil speaker (assuming it's a FC because of the lack of an output transformer on the amp) and it's power transformer has spewed some black goo (only the most scientific descriptions and terms come from me).

It looks almost exactly like this


That particular model appears to have an output transformer under the chassis (unless it's a choke) which mine doesn't. I guess what I am after is some opinions on the feasibility of finding a schematic and further, actually restoring this thing back to full operating condition.

[Chad Hauris]

That photo came from our website...I think that photo is from an RCA console which had seperate 78-33 and 45 rpm record changers.
As I remember it used a permanent magnet speaker....I don't think it had a choke.

You can use a power resistor or the winding from an old power or output transformer of similar resistance to the field coil to substitute for it.

Black tar melted from the transformer is probably due to an overload caused by shorted capacitors or rectifier tube. Make sure you put a fuse in the power line (2 amp or so) to help protect the transformer when repairing the set. There is a possibility the overload damaged the transformer but this is not always the case.

You can see the short check series lamp we use next to the chassis.

Replacing the capacitors and then checking for any further problems such as bad resistors ought to fix it.

[dnewma04]

Thanks Chad! I didn't know that site was from an AK member, thanks for the response. So the tar having melted may not be reason to need to replace it? That was my biggest concern, really.

The other thing is that unlike a lot of old vintage gear, the various tubes aren't labeled on the chassis and are unfortunately missing in action. The only thing present are the 6V6GTs.

A recap and re-resistor, if all that is necessary gives me some hope. I also have some open frame OPTs for PP 6V6s that might work just fine for the application.

Thanks!

[Chad Hauris]

It seems like the tube location diagram is on the inside of the cabinet. This was a unit we repaired for a customer so we don't have it around to refer to anymore but we most likely have some literature for it at the shop...do you have any model number information on it?
Something tells me this set only used one 6V6 output tube but I am not certain of that...you might double check which socket the power transformer wires connect to to make sure an extra 6V6 did not get plugged into the rectifier socket.

[dnewma04]

I will check the cabinet when I get a chance.

The only number I see on the chassis is RC618C. It's got 2 6V6GTs, a 6J6, 6AL5, an unmarked tube and two missing tubes. Along with a 6X5(?) rectifier. I'll inspect the cabinet tomorow.

[dnewma04]

I found the photofact and have been on the hunt for tubes/caps and depending on testing, possibly some resistors. It does mention a 12k ohm OPT for the speaker. So far, finding an appropriate opt is proving to be a little bit elusive but not too bad.

I'll get some pics posted of the restoration.

[dnewma04]

I know this is an old thread, but I thought I might bump it to see if anyone has the photofact for the RCA RC618C. I bought it last year in electronic format and lost it in a recent hard drive failure.

[Tom Bavis]

Sams 73-10 - I'll look (don't hold your breath...)

[Tom Bavis]

Found it - email for a scan - tbavis(at)rochester(dot)rr(dot)com

[dnewma04]

Tom, you are the man! Thanks much. Email sent