Restoration Idea 13
RCA Victor TC-125: 12 Inch Console Restoration
RESTORATION PERIOD: start October 2014 end February 2015
I always wanted to have a vintage TV console, especially the round tube or "roundie" as the collectors call them. Found this one for $45 on Craigslist in the Orange County, CA area. The TV had a lot of cabinet wear but the chassis looks great so I took it home. The model TC-124, 125 and 127 were 12" consoles sold around 1950. They were the last of the round tube consoles, and in the 1950 store ads, the TC-125 sold for an attractive price of $279.95 which was at least $100 less than the new larger rectangular tube TVs. The cool thing about this one is the big solid wood cabinet and big 12 inch speaker built around the small 12LP4 picture tube.
The chassis is the KSC34B which was used in many models. There were chassis variations but they were based on this one. If you look at RCA service manuals from 1949 through 1952 you may see a similarity in schematics with the noticeable changes in the introduction of new tubes.
This TV has 23 tubes plus the picture tube. If you own a RCA 630TS TV the chassis has some similarities as this one. A lot of 6SN7 octal tubes were used as well as 6AG5 remote cutoff pentodes in the video amp section.
Tubes used in this set: 4- 6AG5, 6J6, 2- 6BA6, 2- 6AL5, 12AU7, 4- 6SN7GT, 2- 6K6GT, 6BG6G, 1B3GT/8016. 6W4GT, 5U4G, 2-6AU6, and 6AV6
The Picture Tube or Kinescope is 12LP4. TV consumes 230 Watts.
Table of Contents
Set Evaluation Part 1: SEE BELOW
RCA TC-125 Electronic Restoration Part 2: RESTORE RCA TC-125 PART 2
RCA TC-125 Cabinet Restoration Part 3: RESTORE RCA TC-125 PART 3
Ideas for Restoration HOME Page: HOME
BEFORE RESTORATION
Mahogany finish. The front panel around the picture tube may be a laminate finish so I better be careful. The tuner knob and fine tuning knob are missing.
Complete rear view. The back cover is missing so good chance the TV has been serviced. I am now very sure because the picture has been replaced with a non RCA brand tube. Hope the picture tube is good.
RESULT:Tube is good, reading taken with CRT heater voltage at 5.8-6 V (should be 6.3v). CRT is a replacement and has been used a fair amount but still useable. Keep thegorrilla off my back for now!
3. View of Chassis on top. Need to check the flyback and power transformers, tubes and remove rust and repaint where possible. Look for missing hardware and replace if possible.
4. View of the chassis underneath before restoration. Lots of paper capacitors, 4 multiple can type capacitors and resistors. All the paper capacitors will have to be replaced and the can type capacitors will be opened, insides removed and new ones inserted and sealed (very tedious). All resistors will be checked for value in stated tolerance and replaced as needed.
Notice the long bracket above the Model #- Serial # Tag. That is a multiple tap wire wound power resistor called a CANOHM. Popular from 1940-1955. The chassis serves as a heat sink or dissapating device. their main problem is that over time the heat and cooling can separate the wire from the contact or snap the wire in between. Only simple solution is replace with individual power resistors or design a reactance load with capacitors which is more effiecient.
RESTORATION BEGINS-
The SAMS Photofact for the KCS-34B chassis gives the resistance values for these two difficult to replace parts. Result they both check good (a big sigh of relief). Some restorers like to turn the set on before any major restoration begins and check these parts, thay way they can get a quick diagnosis before putting too much time and money on it. With a lot of 60+ year parts and primitive components, it gives me a scary feeling of disaster if I did that. I'll play it safe and make the changes before turning it on.
3. Remove, open and rebuild FP or can type electrolytic capacitors
2. Taking the can out is always time consuming because the mounting tabs are twisted to lock them in. Often these tabs are the negative connection so they have a lot od residual solder on them. You wind up with TWO challenges, remove as much solder from the tabs and make sure the straight as possible so it can be pulled out. 3. Take the can out and saw off the base as shown, then heat the top of the can with a heat gun to soften the adhesive to pull the can off.
4. Remove all paper capacitors and check resistor values to verify value
The tuner selects the stations and sends the signal to the rest of the TV set. Unlike modern television with digital tuners, vintage TVs used mechanical switches that over time had dirty contacts. The switches need to be lubricated to make turning easier.
5. Cleaning contacts and replacement of parts on the station tuner
Removal required tagging wires, unsoldering and unscrewing the mounting screws. The fine tuning control uses a speed reduction belt and gear system. The leather belt was replaced with a 4.2" DIA flat rubber belt.
The contacts over the years are tarnished and a film of grime has built up. First contact cleaner or alcohol is used to remove most of the grime. Then where possible a pencil eraser is used to polish the contacts. Contacts that were not acessible a cotton swab is used with alcohol and the contact was rubbed. Contact cleaner is sprayed again and wiped dry. Resistors and other parts were inspected to determine if replacement is required.
6a More Discoveries
This resistor was used as a cathode bias resistor for a 6K6GT video sweep amplifier. The marked value appears to be 270 ohms. It measured over 1720 ohms as shown on the Fluke 8000A Lab DMM. The schematic and parts list from two sources, SAM's Photofact and 1950 RCA Service Manual say 2700 ohms. I unsoldered it and it appears to be factory installed. Maybe RCA installed the wrong part.
8. CRT Aquadag Replacement
Early CRT's used a water based graphite coarting on the bell of the CRT to provide a uniform electric field, reducing picture distortion. Over time the coating flakes off and must be replaced.10. The Big Moment
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GO TO RCA TC-125 Console TV Restoration Part 2: RESTORE RCA TC-125 PART 2
GO TO RCA TC-125 Cabinet Restoration Part 3: RESTORE RCA TC-125 PART 3