View Full Version : RCA 721TCS resurrection


bandersen
12-22-2016, 04:03 PM
Thanks to Eric's tip, I recently scored this empty 1947 RCA 721TCS cabinet. Been looking for one for years. Much harder to find than the tabletop top version. Would have been nice to get the insides too. I didn't ask but the seller likely tossed them. She also did the funky paint job assuming someone would want to use it for a piece of decorative furniture. She was amazed that I was going to turn it back into functioning TV.
https://c5.staticflickr.com/1/450/30934235004_ef0152d280_z.jpg (https://flic.kr/p/P8y3ko)

https://c3.staticflickr.com/1/580/30934234514_59ca3478fd_z.jpg (https://flic.kr/p/P8y3bW)

I'm hoping this is the correct, original speaker ?
https://c5.staticflickr.com/1/421/30934233924_db40af9d0a_z.jpg (https://flic.kr/p/P8y31L)

Now I'm not totally nuts as last year I happened to have picked up a tabletop 721TS for $20 with a rough cabinet. So a little chassis and knob swap and I'll be in business. Also that tabletop chassis is all original and actually working pretty well. Amazing that the caps held up so well.


Here it is down at my storage unit where I was hoping to swap the chassis, but I forgot to bring a screwdriver :drool:
https://c6.staticflickr.com/1/558/31691812301_9283086eeb_z.jpg (https://flic.kr/p/QhuPEV)

Looks like latex paint and hopefully not too hard to strip off.
https://c2.staticflickr.com/1/444/31691811561_f56538d6b2_z.jpg (https://flic.kr/p/QhuPsa)

https://c7.staticflickr.com/1/687/30967712574_7fd337b140_z.jpg (https://flic.kr/p/PbvC3S)

https://c1.staticflickr.com/1/771/30967712144_b54859d731_z.jpg (https://flic.kr/p/PbvBVs)

bandersen
12-22-2016, 04:08 PM
Here's a look at the donor chassis in all it's cadmium corrosion glory.
https://c1.staticflickr.com/6/5825/20742049624_7d687a8e78_z.jpg (https://flic.kr/p/xAUqHf) https://c3.staticflickr.com/6/5784/20742059354_c65388457e_z.jpg (https://flic.kr/p/xAUtB1)

I checked it out back when I first picked it up and amazingly it works fairly well on all original caps.
https://c8.staticflickr.com/6/5688/20778618023_d77f9f927b_z.jpg (https://flic.kr/p/xE8RdT)

Even the often bad bleeder resistors are OK. I figure I'll restuff the caps eventually.

https://c1.staticflickr.com/1/760/20833970344_11323cabef_z.jpg (https://flic.kr/p/xK2xxf)

https://c4.staticflickr.com/6/5654/21456659115_26a3acf2a4_z.jpg (https://flic.kr/p/yG3Zdx)

Eric H
12-22-2016, 05:48 PM
The speaker looks like the one in mine so pretty sure it's right.

I'm guessing the seller got it without guts, none of the knobs are from that set so either it didn't have knobs or didn't have a chassis when they got it.

It looks like it's pretty solid, hopefully the veneer is intact under that paint.

bandersen
12-22-2016, 06:14 PM
Cool. I'm thinking I just need to disconnect the field coil and output transformer in the 721TS chassis and run the wires down to the bigger speaker ?

Eric H
12-22-2016, 06:40 PM
Well that's interesting, seems odd they'd relocate the output transformer for the console version, perhaps it's a different impedance on the bigger speaker?

N2IXK
12-22-2016, 06:59 PM
Yes, the TCS relocates the audio output tranny to the speaker frame. The speaker field is also supposed to be part of the 5-pin plug, which incorporates a jumper in the B+ circuit to prevent the set from operating with the speaker plug disconnected.

There is also an extension from the filament supply to a #47 pilot light at the bottom center of the cabinet.

bandersen
12-27-2016, 10:58 AM
That you for the info!

I tried installing the 721TS chassis and knobs but quickly ran into a few problems. First, the speaker definitely needs to be removed as the chassis will not slide far enough into the cabinet.

Secondly, I'm not sure how to install the channel dial plate. It looks like I need to unmount the cabinet font and it has two wing nuts just like the TS, but something is holding it firm at the bottom.

https://c6.staticflickr.com/1/540/31727435821_ac882d45f5_z.jpg (https://flic.kr/p/QkDpix)

I'm guessing there may be a screw hidden under this brass piece ? Perhaps there are some screw inside ?

https://c2.staticflickr.com/1/734/31033913673_e4a450404a_z.jpg (https://flic.kr/p/PhmVk8)

N2IXK
12-27-2016, 11:10 AM
The CRT bezel comes off with the wing nuts. The lower edge is held in place by the brass trim piece, which doesn't need to be removed, IIRC.

Removing the grille involves a bunch of screws from inside the cabinet, which hold the grille and the surround in place.

bandersen
12-27-2016, 11:38 AM
Thanks for the info. I'll take a look tonight and see if I can get it apart. I also picked up an original RCA service supplement and owners manual on ebay. I'll scan and upload to the ETF when I get them.

https://c8.staticflickr.com/1/757/31915019495_3e3922e5fb_b.jpg (https://flic.kr/p/QCdPoP)

vts1134
12-27-2016, 02:35 PM
Original owners manual :thmbsp:

DavGoodlin
12-28-2016, 10:45 AM
Very cool Bob. This is one RCA where the console version is preferred over its table version.

Electronic M
12-28-2016, 10:48 AM
Very cool Bob. This is one RCA where the console version is preferred over its table version.

Mostly because I can count on one hand the number of survivors I've heard of.

EdKozk2
12-28-2016, 04:00 PM
Bob,
What supports the front of the CRT in this set? Is it just the 4 small metal tabs on the inside front of the cabinet ? Do you insert the CRT through the front like other old RCA tabletop sets from 48 and 49?
Ed

bandersen
12-28-2016, 04:14 PM
Yes and yes. Take a look at the second photo where you can see the wing nuts that hold on the front and the four tabs.

EdKozk2
12-28-2016, 04:31 PM
Thanks Bob,
I couldn't see the wing nuts well, until I viewed the picture on your image hosting site where the image can be enlarged.
Ed

M3-SRT8
12-29-2016, 10:42 AM
Thanks for the info. I'll take a look tonight and see if I can get it apart. I also picked up an original RCA service supplement and owners manual on ebay. I'll scan and upload to the ETF when I get them.

https://c8.staticflickr.com/1/757/31915019495_3e3922e5fb_b.jpg (https://flic.kr/p/QCdPoP)

Oh, yes. Please do. Mine's on the bench right now.:smoke:

bandersen
12-29-2016, 11:13 AM
Sure thing. Funny - there are three of us (Eric, Lee and me) working on this uncommon model right now :scratch2:

Electronic M
12-29-2016, 12:01 PM
Sure thing. Funny - there are three of us (Eric, Lee and me) working on this uncommon model right now :scratch2:

Interesting coincidences like that seem to happen a lot in this hobby....IIRC there are only 2 known examples of that 50's rectangular color westinghouse set but both materialized within a month of each other and were posted about here.

bandersen
01-05-2017, 11:50 AM
I scanned the RCA 721TCS service data and it is available to download courtesy of the Early Television Foundation. Owners manual coming soon.

http://www.earlytelevision.org/pdf/RCA_721TCS_Service_Data.pdf

N2IXK
01-05-2017, 03:30 PM
Thanks for scanning and uploading that, Bob. I managed to restore mine using the 721TS data, but it made for a bit of headscratching when rewiring the remote speaker harness that only the TCS has...

bandersen
01-13-2017, 11:06 AM
I finally had the time and patience to remove all the wood screws holding the front on. I sure didn't expect the whole from to come off like that!

https://c1.staticflickr.com/1/755/31431519744_92e4e34ce2_c.jpg (https://flic.kr/p/PTuKLd) https://c1.staticflickr.com/1/473/32247149756_a83219f866_c.jpg (https://flic.kr/p/R8z59C)

The speaker is in very good condition and I found the pilot lamp and holder to be intact down at the bottom.
https://c1.staticflickr.com/1/319/31431518914_2958ef854c_c.jpg (https://flic.kr/p/PTuKvU)

Unfortunately, the donor plastic dial scale is cracked.
https://c1.staticflickr.com/1/292/31909330720_ece33da9bb_c.jpg (https://flic.kr/p/QBHEju)

I removed the speaker form the donor chassis and it slid right into the cabinet :)
https://c1.staticflickr.com/1/593/32247148776_573640854e_c.jpg (https://flic.kr/p/R8z4RJ)

Then I installed a genuine RCA Victor 10BP4.
https://c1.staticflickr.com/1/735/32247147926_261d34c569_c.jpg (https://flic.kr/p/R8z4B5) https://c1.staticflickr.com/1/527/31909330220_5fbf9a5b5d_c.jpg (https://flic.kr/p/QBHEaS)


Finally, here it is all back together with knobs. If I had access to an outlet, I'd have fired it up. That will have to wait until and I move and get a workshop setup again.
https://c1.staticflickr.com/1/747/31909329790_accb7f1017_c.jpg (https://flic.kr/p/QBHE3s)