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RCA 56X5
#1

The past few nights I have been replacing the electrolytic caps and paper caps in the RCA 36X5 I bought recently. You may have noticed my post in the April 2021 Finds and Losses about it. I posted this picture...
[Image: https://64.media.tumblr.com/fd1eb3926de0...f23dba.jpg]

For a while I had to wait for parts to come in before I could do much. The radio uses a 2 section "firecracker" for its main power supply filtering, 50 MFD and 30 MFD both 150V. I ordered 33 MFD 200V radial condensers, got 10 for a very good price on eBay, USA vendor. In the circuit the negative of both sections goes to chassis ground. I used a 3 section terminal strip, and screwed the grounded lug to the chassis using the original screw from the condenser strap. I also connected it to a hard ground where the original condenser black lead went.I tied two of the 33 MFD condensers in parallel and mounted them on the terminal strip with the negative leads to the grounded terminal. the other leads I connected to a separate lug and wired that to where the 50 MFD section went. I then mounted a single 33 MFD condenser with its negative again to the grounded lug, and its positive to a separate terminal, and wired that to where the 30 MFD section had gone.

Then I tackled replacing all the paper condensers in the radio. Since it is only a six tube circuit, you might think this would be easier than on a larger, more complicated chassis, but that isn't always the case. Here the chassis was rather compact considering what all they fit in it, a six tube circuit with a stage of RF amplification. Being an AC / DC set did help in that there was no power transformer to deal with. Still, the parts were quite packed in there, some in layers, and took some careful surgery to replace the paper condensers without screwing things up. In the end though, I got them all replaced in the wee hours of this morning.

I had an appointment with my retina doctor today and got a shot in my right eyeball for macular degeneration. Things are going very well. I never actually noticed any loss of vision in my right eye, but did in my left. It was diagnosed once they had replaced my left lens which was obscured by a cataract. Then I began treatments, a shot in each eyeball every 28 days, so, for months I went every 2 weeks, and got a shot in one eye, and in the other two weeks later. This went on from August until March. Now I only need to go once a month and the shots are stretched out to two months apart for each eye. I got back my full vision in my left eye, which is quite unusually good, and as I said, I never really lost it in my right eye.

Anyway, when I got home, and settled back in, I tested the tubes. The 35Z5 was bad, and the 12SQ7 is weak but barely tests good. I had both in stock, and have ordered replacements. I also ordered a box of type 53 14.4V pilot bulbs since the one in the radio was blown out. I installed the tubes and tested the radio tonight. IT LIVES ! I next have to repair the loop antenna on the back which is pretty beat up but working. Just need some glue and cardboard for that. I'll tend to that tomorrow. I am also still waiting for my dial glass and decals. Hope they come some time soon. In the meantime I'll have the alignment and then refurbishing the cabinet. Then, once I install the new dial glass, she'll be done. I'll post an after picture once she is finished.
#2

Nice, you will like the set. RCA was stiil making half way decnt stuff in 1946. I have mine upstairs and been using it off and on, battered cabinet and all.

Paul

Tubetalk1
#3

Hello Mike,
what great Set and I really look those older RCA radios too I am finishing up a Bendix from about the same time period for a customer this weekend and it also had one those firecracker capacitors and I too am going to do the same The terminal strips work great .
Sincerely Richard
#4

Today I made a new back for my radio. The old one was falling apart in layers. Fortunately the antenna loop windings were still intact. I glued two layers of cardboard from a large cereal box together, three would have been better, but I only had the one box empty, and so used the front and back, gluing the printed sides together, which left the brown inside cardboard showing, which looks pretty much like the old stock RCA used. Like I said, 3 or four layers would have matched the original better, but this does OK. I then carefully removed the loop from the old back, very carefully desoldering the leads so as not to lose any length. I traced the old back on the new cardboard when it had dried together, and cut out the new back with an Exacto. I then sprayed the new back with polyurethane, first one side, then the other letting each side dry. I screwed two three terminal strips to the back. Then I glued the original winding onto the new back just as it had been on the old back. I wrapped the leads from the loop around the appropriate terminals. I also wrapped a foot long red stranded 20 gauge wire end around a terminal on one of the strips (number 3 on the schematic) Then I mounted the new back on the radio and connected all the leads. It looks fine and works as it should. For those interested, the schematic can be found here : http://www.nostalgiaair.org/Resources/996/M0014996.htm
I'm still waiting for the dial glass and the decals. I'll begin work on the cabinet tomorrow.
#5

Tonight I did a complete alignment on the 56X5. I guess somebody with nothing better to do began to play with visible screws because things were WAY off. First I set the IF, had to reset both adjustments on both IF transformers, A LOT. Went back and forth a few times and got them peaked at 455KC. Then I went on with the rest of the alignment and had MAJOR adjustments at every stage, but finally got it all dialed in. It receives well on both the standard AM broadcast band and shortwave, despite having a marginal 12SQ7 first detector/oscillator tube. I even was able to pick up WWV at 10 MC using just my 10 foot indoor test antenna, not to mention quite a number of other shortwave stations in both the 9 - 10 MC and the 11 - 12 MC international broadcast bands. It will be fun to see how this radio performs once I have it all finished, have installed a new 12SQ7, and test it on my outdoor antenna.
#6

I have been doing a basic freshening up of the cabinet. I cleaned it well with Goop, and found that once clean, and while still wet from the Goop, the cabinet actually looked pretty good. That told me that, once it dried, a couple of coats of tung oil would bring the finish back to looking pretty acceptable. So, that is what I did. I rubbed on a thin coating of tung oil and let it dry. In a couple of places the old finish was a little checked, so I then sanded it with 400 grit paper, and then wiped on another coat. The cabinet is again drying, and looks quite acceptable, not like new, but like a well kept, and much used antique. I forgot to take any before pictures of the chassis this time, but dove right in. Here is a picture of the completed chassis as it stands tonight, new back and all...
[Image: https://64.media.tumblr.com/70e60f4be240...29969f.jpg]
#7

Today I finally received the replacement dial glass for the RCA 56X5 I have had on my workbench for months now. I installed the glass into the cabinet which I had already cleaned up as I said before. The new dial glass looks much better than the original which had some letters and numbers scarred and peeling. I tried it out on my outside antenna, and it works quite well on both bands. It's not up to the 18T or T8-18, but it is pretty good. I have to admit, my penchant for top end shortwave receivers has spoiled me. So, here is the finished product...
[Image: https://64.media.tumblr.com/91b6044bde2d...fe6866.jpg]
#8

Looking good!

I don't hold with furniture that talks.
#9

DX the Broadcast band with it, mine does OK.

Nice Job, looks authentic.

Paul

Tubetalk1
#10
Video 

Here's a demonstration of my RCA 56X5 in action...
[Video: https://www.youtube.com/watch?v=jBu2sP3Q92M]




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