Sony Model 8-301W Portable Television (1961)

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

The World's First . . . Something

Urban Legend #1. Sony advertised this TV as "all transistorized," which stretched the truth a bit. 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 introduced in the 1940s by Hallicrafters, Sentinel, and others.

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

Description

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

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 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 this one 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.

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 fine. The raster is dim, with no sign of the broadcast image, as if the video signal simply isn't getting through.

The picture tube shows a fuzzy dark area in the center, which can be a symptom of "ion burn" on some tubes. I don't know offhand if this kind of tube is subject to that problem, and I'll reserve judgment in any case, until I see an image with normal brightness. In this state, you can barely see the raster at all in normal room light.

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 also makes this TV extremely difficult to service, compared to an older tube set. 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. 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.

Sony factory techs might have had those special cables, but I don't, and I'm not about to build a set of custom cables that I'll never use again. I'll have to do the best I can, testing components passively on the detached boards and putting the TV back together when I want to see the result of replacing a part.

Mediocre Construction Quality

My first look at the boards did not impress me with Sony's construction quality. The 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 finally had to burnish it off 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, a sign of cost cutting.

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.

In the 1960s and 1970s, Sony sold many so-called "tummy TVs," small enough to watch while perched on your stomach. Repairmen found them unreliable and difficult to service. I rescued this 5-307UW from the garbage pile at an estate sale. It probably needs new capacitors in its vertical section.

To Be Continued

That's where things stand right now. If the boards were more accessible, it would be straightforward to diagnose the problem.

The tuning and audio work well, so we know the problem arises somewhere after the sound is picked off the signal for amplification. That rules out the four IF (intermediate frequency) amplification circuits, as well as the tuner and audio. What's left are the sync, sweep, and video output circuits.

An oscilloscope offers one way to locate the problem. You begin near the pickoff point and work toward the picture tube, comparing the model waveforms in the schematic to what you see on the scope at each test point. If the waveforms match, you move to the next test point. If not, you stop and investigate.

Testing voltages is another debugging method. Again, starting at the pickoff point, you check the voltage at each test point shown on the schematic. If a voltage is significantly off, that's an area to investigate.

A third method is testing resistances. For many old tube TVs, the service manual includes a resistance chart, showing what resistance should be found at every pin of every tube in the set. Even though I can't check waveforms or voltages under power, I could at least pull each board and check resistance at likely test points. The Sams manual for this TV has no such chart, unfortunately.

Locating the problem without these aids is not impossible, but it will be more tedious than usual. Stay tuned . . . .