Sony Model 8-301W Portable Television (1961)

              

              

The Sony 8-301W transistor television was introduced in 1961 and it sold well, considering its hefty price of $249.95. The distinctive profile makes it a favorite of collectors.

Here's a photo of my 8-301W after restoration:

The World's First . . . Something

Urban Legend #1. Sony advertised this TV as "all transistorized," which stretched the truth a mite. Although the 8-301W has many transistors, it uses two small 1DK1 tubes as high voltage rectifiers. That's three tubes if you count the picture tube.

Urban Legend #2. Some people call this the first transistorized TV, but that's wrong, too. The Philco Safari was introduced in 1959, two years before this set. Like this one, the Safari uses two rectifier tubes in addition to many transistors.

Urban Legend #3. Another mistaken claim is that the 8-301W was the first portable direct-view TV. (Direct view means you view the picture tube directly, rather than in a mirror as with the Safari.) Portable direct-view TVs were sold in the 1940s by Sentinel and other companies.

A more truthful description of the 8-301W might be, "the first mostly-transistorized portable TV that Sony sold in the United States."

Catchphrases aside, this is an interesting example of early transistor TV technology, and I was curious to see how well it would work, once restored. In this whimsical magazine ad, Santa holds an 8-301W on his lap while elves busily stock the shelves with other Sony products.

This ad from the October, 1961 issue of Ebony magazine gives more details. The list price was $249.95 and the optional rechargeable battery cost another $29.95.

Description

The 8-301W has an all-metal case with an adjustable hood. It's a true portable, using either AC power or a 12-volt DC source. Surprisingly heavy for its size, it tips the scales at more than 13 pounds, with another 4 pounds for the battery pack.

The factory paint is a textured gray that makes the TV look more like a piece of test equipment than a snazzy portable. A previous owner painted mine pale yellow, which I like better. Here is a view of the back.

As noted on the backplate, the TV uses 23 transistors, 18 diodes, and two tube rectifiers. The power socket is at upper left. Four small knobs on the back are labeled Gain, Brightness, Vertical, and Horizontal. The 8-301W lacks a contrast control.

The TV came with a zippered vinyl carrying case. I also have a small Sony adapter for connecting an external antenna.

The TV has an oddball power connector. If you see burn marks around the connector, check the power supply carefully. Somebody might have tried to hot-wire it with a homemade cable and guessed wrong about the connections. Sony sold this television in Europe as the 8-301E, using 220-volt rather than 120-volt AC power.

The large battery pack is seen in the following photo of someone else's TV. Many of these batteries have been discarded by now, as they eventually lose their ability to recharge.

The previous photo also shows the standard factory paint, a medium gray with a slightly textured "wrinkle" finish.

The 8-301W must have been very popular, since they are still plenty of them floating around. If you pay much more than $100 for one, you're not shopping very carefully. I have seen scruffy ones at swap meets priced as low as $20 with no takers.

Disassembly

Begin disassembly by removing the screen hood and chrome trim strips. The strips pull off after you remove two screws in the back. Then you lay the TV down on its face, pull the knobs, remove screws from the back and sides, and slide the case up and off. The case may be stuck on the front rather tightly. Don't damage things by prying it off carelessly.

The speaker and power switches remain attached to the chassis by a set of wires and needn't be removed from the speaker plate. Here is the chassis from each side after I removed the case.

        

The second photo shows four fat capacitors used in the power supply. The picture tube socket is bright green. This TV uses dozens of small electrolytic capacitors, and you can see several of them clustered on the tightly-packed circuit boards.

Even using miniature (for the time) components, it was quite a trick to cram an entire television into the space around the neck of the picture tube. A customer's dream . . . and a serviceman's nightmare!

First Power-Up

Before getting too carried away, I tested the type 210HB4 picture tube. If the CRT is dead, this TV may not be worth restoring. My Sencore CR-70 tester doesn't have a socket for this tube, so I used the universal adapter, which has little probes that clip to the CRT pins.

The test showed strong emission, a welcome sign. The needle moved well up into the green Good zone. When I powered up the television, here's what I saw:

The audio came through loud and clear, indicating that the tuner and audio circuits are working, at least marginally. The raster was dim, with no sign of the broadcast image, as if the video signal simply wasn't getting through.

It's not surprising that the TV needs work. Early solid-state televisions use lots of little electrolytic capacitors, and after 50 years, one would expect some of them to fail from drying out over the decades.

Cleanup and Further Investigation

The next step, routine in all restorations, is to clean the controls and anything else that needs it. The chassis lifts off the picture tube as a unit after you remove several screws and free the yoke and CRT socket. Don't forget to pop out the CRT anode, whose lead is very short.

The three circuit boards unplug from the chassis after you remove a couple of clips. They comprise functional modules for vertical/horizontal sweep; video IF; and video output, sound, sync, and horizontal AFC.

This modular design speeded up factory service. The technician could quickly identify which board contained the problem, plug in a new one, and pitch the old board into a bin to be reconditioned (or perhaps just discarded).

Modular design makes this TV tricky for a hobbyist restorer, compared to an older tube set. When the boards are plugged in, they're so close together that you can't reach anything to test voltage or check waveforms on an oscilloscope. With the boards unplugged, it's impossible to power up the TV for diagnostics unless you have a set of extension cables with matching sockets and plugs to hook everything together on the workbench.

Sony factory techs must have used special cables like that. I'm not about to build a set of custom cables that I'll never use again, so I'll do the best I can, testing components passively on the detached boards and putting the TV back together when I want to see it play.

Mediocre Construction Quality

My first look at the boards did not impress me with Sony's construction quality. This circuit board has big, sloppy globs of solder and the board's contact fingers are dark with corrosion:

A close-up identifies the culprit. Check out these greasy fingerprints left behind by a careless assembler. Hadn't gloves been invented by the 1960s? Although these prints began as grime, they eventually corroded the contact metal. Chemical cleaning didn't touch this hard corrosion. I gently burnished it with a Dremel power tool.

I normally don't use such methods on contacts, which are often plated with a thin layer of precious metal. These contacts are plain old copper, however.

I then cleaned the controls and reassembled the TV. It showed no dramatic improvement, but cleaning did eliminate slight scratchiness in the Volume and Gain controls.

Replacing Electrolytic Capacitors

Replacing capacitors is a common procedure, so if you're unfamiliar with the process, refer to my recapping article for basic how-to advice.

This TV sat around for about a year, until I acquired an instrument that greatly simplifies restoring solid-state electronics. It is an EDS 88A capacitor analyzer:

Also known as an ESR tester, the 88A can test electrolytic capacitors without disconnecting them from their circuits, a time saver when a device contains dozens of electrolytics.

When I pulled the PC boards and started testing, around twenty (!) of the old caps were clearly defective. No wonder the screen showed only a blank raster. I'm surprised that the TV showed any signs of life at all.

I marked the top of each bad cap with a red X and dove in. Just as with tube electronics, the modern caps are smaller than the originals. Here, I have disconnected one leg from an original 100-mfd capacitor, holding its replacement nearby.

Access to a couple of the bad caps was blocked by this shield, located on the foil side of the high-voltage section:

To remove the shield, you unsolder four lugs from the board and unscrew two insulating spacers. Don't forget to reinstall the spacers when you're finished here. They prevent the board from shorting against the shield.

Here are the PC boards after installing a number of new electrolytics:

Reassembling the 8-301W

I'm ready to reassemble the television for a tryout. The first step is to plug the boards into the main chassis and connect a few cables. The smaller video board goes behind the two larger boards.

The boards are installed and I have gathered the rest of the parts.

Final assembly is done with the CRT face-down on the workbench. The main chassis is carefully lowered over the CRT neck and screwed onto the CRT frame. Then the main housing is lowered and screwed in place. Lastly, the speaker panel is screwed into the bottom.

First Picture

Enough messing around. Let's see how the TV works with fresh capacitors.

Not perfect, but not too bad, either. Yes, we're lacking horizontal sync, but the picture has good brightness, contrast, and focus. The channel selector and fine tuner are working well, and the audio is excellent. The basic recapping made big improvements.

The blizzard of horizontal lines indicates that the horizontal frequency is far off the mark, which is 15,750 cycles per second. In the next photo, I am using a nonconductive tool to adjust the horizontal frequency control on the sweep chassis (now, the picture tube is lying sideways):

If you compare the two previous photos, you'll see that the number of slanted bands is fewer in the second shot, a sign that the adjuster is taking us in the right direction. (Eventually, the picture would resolve into a single band and the picture would straighten up.) The adjuster soon hit the end of its travel, however, so adjustment alone won't solve this problem.

Then I remembered that I had replaced one electrolytic with a value different than the original. It is capacitor C34, one of those shown with yellow highlighting to indicate that they were replaced:

The original capacitor has a value of 1 mfd, rated for 12 volts. I couldn't find an exact replacement at Mouser, so I had used a slightly higher value, 3.3mfd/16v, hoping that this would work.

Looking at the schematic, you can see that C34 is near the horizontal frequency control, and it's on a line bringing some sort of feedback from the horizontal driver transistor (X19) back to this area where frequency is determined. My replacement is more than three times the specified value. Could this be messing up the frequency?

Generally speaking, where a capacitor performs a simple coupling function—passing a signal from one circuit to another —its value isn't that critical. However, if it's part of a tuned circuit, designed to resonate at a certain frequency, the value is more important.

This capacitor acts as a coupler, passing a feedback signal from the drive transistor, and it's also paired with L13, described as a peaking coil in the manual.

This type of horizontal circuit was unfamiliar to me, so I called on the VideoKarma solid-state TV forum for advice. The discussion suggested that the incorrect value might be causing the frequency problem, so I ordered a 1mfd/25v capacitor.

Fixing the Horizontal

A couple of days later, I installed the new 1-mfd capacitor, but that alone didn't cure the horizontal problem. A couple of forum members suggested looking at non-polarized capacitors C98, C99, C100, and C101, all located in the horizontal AFC section.

At the same time, I found out about a new electronics store in the area. Off I went for a field trip, returning with a little sack of components.

First to go were C100 (.005) and C101 (.02). The store didn't have any .02 caps, so I made one by wiring two .01 caps in parallel. The photos show the corner of the sweep board before and after the replacement:

  

Bingo!

My doubled-up cap worked fine. With only a slight turn of the horizontal frequency control R4, the picture snapped into place and held stable.

The picture is snowy because I'm receiving a broadcast from the transmitter on the other side of the house, which is not strong at this range. Plus, there's plenty of RF interference in my workshop from sources like compact fluorescent light bulbs.

The signal from my test pattern generator is stronger, requiring that I turn down the Gain control quite a bit. It also lets me judge the Sony's screen geometry:

The vertical centering and linearity are quite good. The center dot is at the middle of the screen and the squares are about the same size at top and bottom.

The horizontal linearity is fairly symmetrical, but when the dot is centered, there are eight squares on the left side of the screen, and ten on the right. You can see that squares near the left margin are stretched more than squares in the center zone. This is common with old tube TVs, which, if they have a linearity defect, invariably stretch the left side. This TV, however, also shows stretching near the right margin, as well as slight warping of the rightmost vertical lines.

In the VideoKarma discussion, Hugh, who had restored several of these little TVs, remarked that their horizontal linearity simply isn't great. He also offered advice on finding the best compromise by adjusting the Horizontal Drive and related controls.

I did the best that I could, understanding that perfect screen geometry might be unobtainable, given the TV's design limitations. This TV has fewer adjusters than many old tube TVs (there is no Width control, for instance). Its adjusters are also quite interactive, meaning that adjusting one parameter changes another—not always in the way that you would want. For example, the Gain control has a noticeable effect on the vertical warping near the right screen margin.

Finishing the Recap

I had already ordered enough new electrolytics to completely recap the TV. I re-checked all of the remaining caps with my ESR tester and decided that my earlier tests had been a little too lenient. The closer I looked, the more marginal caps I found, so I decided to finish the job.

In the first photo, I have clipped the ends of three electrolytics, making it easy to remove their clipped stubs from the foil side of the board. The second photo shows the new parts in place.

  

On we go, and the discard pile keeps growing. The Swiss army knife shows you how small these electrolytics are. Their modern replacements are even tinier.

By the end, I had replaced more than 30 small electrolytics. I did not replace the four big electrolytics in the power supply, however. My tester shows they are in good shape and the power supply voltages are right on the money.

Final Thoughts

After reassembling the TV and making a few more adjustments, I was pretty happy with this project. Here are a couple of unretouched screen shots of the Sony at this stage.

  

It's interesting to compare the Sony 8-301W to the RCA 8-PT-7030, a "miniature" tube TV from 1956. The RCA was about as small as you could make a tube television at the time, and, like the Sony, its electronics are carried on small subchassis that wrap around the neck of the picture tube.

     

You can read more about that television in my RCA 8-PT-7030 article.

Is the Sony 8-301W a great performer? Well, not really. Apart from substituting transistors for tubes, the basic electronic design is conventional for 1961. In a side-by-side comparison with the RCA 8-PT-7030, designed five years earlier, you might find them pretty comparable in performance.

What set the Sony apart was the packaging, made possible by solid state components. Few other companies offered such a compact, truly portable TV at the time, and this set helped blaze a trail that mainstream TV makers would soon follow, into the transistor age where "tummy TVs" and even hand-held sets would be commonplace. Understood in that context, this little Sony was successful, despite certain design restraints.

©1995-2014 Philip I. Nelson, all rights reserved