This gem of a mid-century modern styled CRT TV turned out to be a simple e-waste rescue, cleaning and restoration. No major repairs were needed. However, this is a good opportunity to review CRT high-voltage safety and some of the limitations of restoration projects in general.
This is a 13″ black and white CRT TV manufactured in 1976. It was assembled in Korea, with an Orion picture tube and sold by Sears & Roebuck. Huge numbers of these and similar models were sold over the years, so there were countless variations on this design. The rounded design and originally off-white coloring was popular in the 1970s.
It has a basic compliment of controls. The two large knobs on the front select the VHF or UHF channel and each has an outer fine tuning ring. Three small, but easily accessible knobs on the right side provide combination pull-on/volume control, contrast and brightness adjustment. On the rear of the set are vertical alignment, vertical size and vertical hold adjustments. On the top rear of the set are the built in VHF telescoping monopole and UHF loop antennas.
Part 1 – Retro Bright
The retro bright process is a fantastic-almost magical-way to make faded and yellowed plastics look new again…sometimes.
This TV is a good example of different types of plastics and how they age differently. The main case had significant yellowing. You can see it was worse on the front, since the TV was likely placed up against a wall. There were probably one or more windows in the room, and even with curtains or blinds, the Florida sun can be fierce.
Compare the top of the case to the inside of the battery door to see the extent of the yellowing. Interestingly, you can also see that the adjustment knobs on the right-hand side were almost completely unaffected. These before and after photos show that despite an extended treatment period (2+ days), noticeable yellowing remains. Since these parts were large, I used the vapor method instead of my usual sealed bags.
There are a few other features to note. The built-in carrying handle and large battery compartment imply this TV was designed to be portable. The proprietary power plug may have been designed for a different model, since on this unit the bottom two pins are wired to live and neutral and the rest are not connected. The metal snap on the side of the socket is also not connected and only used to secure the plug in place.
Despite the retro bright process not being entirely “successful”, it still substantially improved the look of the TV. It evened out the overall coloration of the case while retaining what could be considered a vintage style patina.
Part 2 – High Voltage
* Caution! Do not disassemble a CRT unless you are familiar with high voltage devices. These units run on thousands of volts *
That warning pretty much says it all, but let me illustrate it with some photos. On many TVs and monitors, the high voltage wire running from the flyback transformer to the tube is red as a warning. Here it is white. A high voltage probe is commonly used to test and discharge the anode when servicing it. Since this is a single electron gun B&W tube, the working voltage is around 8-10 thousand volts. Color tubes can have working voltages of 30 thousand volts or more!
Part 3 – Ratty Cords & Tired Tubes
With that out of way, on with the restoration! As with any vintage electronics, we never just plug something in without inspecting and testing it first.
The original ungrounded power cord was intact and had continuity without any shorts, but it did have a number of cuts in the insulation which had been sloppily wrapped up with electrical tape by the previous owner. I see this incredibly frequently, and while it might make you feel safer and prevent someone from getting a casual zap from the cord, it doesn’t fix the underlying problem.
In a single insulated cord, a small partial cut can easily allow the two wires to short across to each other-even if the outside is wrapped with electrical tape. This is of course a fire hazard and can damage the attached appliance. A proper repair involves either replacing the cord entirely or removing the damaged sections and reconnecting the good portions of the cord together. In this case, the damaged areas were small and since the appliance side plug was proprietary I decided to remove the damaged sections and repair the cord.
Once the cord was sorted, It was time to move on to the main event. The case was held together with only three screws. The rear half of the TV was connected to the front half by the antenna wires and a power cable, all of which used easily serviceable connectors.
Thankfully, all the fuses were still good, all the power supply wires were intact and the main transformer, despite having a very slight hum when energized, steadily generated all the correct voltages. Many times a dead or damaged main power transformer will make a device unrepairable. Finding a replacement transformer can often be a considerable challenge, and rebuilding one requires specialized knowledge I don’t have.
Turning to the business side of the TV, after I checking for any damaged wires, crt neck damage, crusty or blackened circuit board components, cracks in any of the circuit boards or any infamous “brown gunk” that can become conductive and lead to shorts, I felt comfortable doing an initial power test.
In what is often the first major milestone of a project, the TV was plugged in to an isolated power supply, the power knob was pulled and the sound of static followed by the soft glow of black and white snow filled the shop!
The TV had initially appeared surprisingly clean overall and was apparently well cared for. The tinted plastic front covered had protected the tube well, and the crt had no visible scuffs or scratches on it. There was surprisingly little black dust on the tube or inside of the case. However, the picture seemed a little dim. What will my B&K CRT restorer/analyzer say? Keep reading to find out.
I find these older circuit boards just beautiful. This one cleaned up wonderfully with a gentle brushing and vacuuming. It is well labeled, all the components appear to be a of good quality and it even has some neat-looking wire-wrapped connections.
Part 4 – Testing & Final Touches
After removing 47 years of dust, grime and sun damage, we can work on some final details and do some more in depth testing.
Everything was reassembled, the potentiometers behind all the dials and knobs were given a cleaning with some Deoxit brand fader lube, the protective front cover was installed, and the UHF loop antenna was touched up with some chrome spray paint. A proper repair for that would have been to send it out to a company that does actual re-chroming, but that is a labor intensive process and would have been prohibitively expensive for such a small part.
When I first turned on the CRT is seemed a little dim and required the brightness and contrast knobs to be adjusted to about 3/4 position to look decent, so I hooked up my trusty B&K 467 CRT restorer/analyzer.
With the tester connected and properly dialed in, I got a nice bright heater glow from the tube and no shorts were indicated. The CRT also tested solidly in the “good” range of the meter, with the “Life” test only dropping the reading a couple notches and the “Focus” test coming back okay. The B&K analyzer has a clean/balance function which is mainly for multi-gun color tubes, but I think it is less risky to do than a full rejuvenate. Unfortunately, it didn’t make any appreciable difference to the picture or tester reading.
So, should this CRT be rejuvenated? If I were restoring this TV for a customer, I would strongly recommend against it. The tube still has a decent picture, and while the brightness needed to be adjusted to 3/4, it could have been much worse. CRT “Rejuvenation” carries a significant risk of damaging the tube with no guarantee that it will improve the brightness, as Adrian Black, from Adrian’s Digital Basement can personally attest to.
That being said, since this TV cost me nothing and was not from a customer, I decided to try rejuvenating it. The result? After a single rejuvenation, the CRT tested one notch higher on the “good” meter, but there was no visible difference in the brightness of the picture.
Having successfully tempted fate and basically broken even, I buttoned up the TV and am happy to call this a very successful restoration overall. Yes, the TV shows it’s age with the somewhat weak picture and still slightly yellowed case, but that helps it tell its’ life story. For anything vintage or retro, context, provenance and history matter. This little entertainer still has plenty to talk about.
Total Restoration Cost $175