Philco Model 4654 Predicta Television (1958)

      Movie 1   Movie 2

Is this the ultimate TV? Love it or hate it, the Philco Predicta television is unarguably one of the design icons of the 20th Century. Collectors cherish the Predicta for its "space age" look, but repairmen (and women) grumble about its hard-to-service innards.

Philco produced the Predicta from 1958-1960. Several models were available, in console or tabletop cabinets and with 21-inch or 17-inch screens.

This console style was called the Pedestal and it was sold in 1958. The top is painted yellow and the rest of the cabinet has a mahogany finish. The first photo shows the TV operating at the time of purchase. My set has only a VHF tuner for channels 2-13. Some Predictas also included a UHF tuner.

The 1958 line also included the Holiday, essentially the same TV in a low wooden tabletop cabinet. Another 21-inch console, the Penthouse, had a blonde lowboy wooden cabinet and a movable screen attached to the cabinet with a long cable. I never quite saw the utility of this scheme for home use. How often would you want to lug a heavy CRT around your living room to a different location? I've read one suggestion that it was handy for bars, where you could put the screen close to customers but keep the channel changer out of the patrons' hands.

By far the most common Predictas were the 17-inch tabletops, with metal cabinets in a choice of colors. These sets were introduced in 1959 and I have been told they were more reliable than the 21-inch Predictas, using transformer power supplies rather than transformerless AC/DC type supplies. Two of the tabletop names were Princess and Debutante, perhaps suggesting they would make good TVs for a lucky teenage girl's bedroom. The Siesta tabletop included a clock that could turn the TV on and off at a designated time. Many tabletop Predictas were sold to motel chains.

The last upright Predicta, sold in 1960, was the Continental. Its profile was similar to the Pedestal, but the cabinet had a Danish Modern design with four finned supports attached at an angle to the central box.

The free-standing picture tube is almost unique in the history of TV design. The German Vega company produced a tabletop model that looks much like a tabletop Predicta. I have seen photos of that set, but never seen one in the flesh. The closest (perhaps the only) lookalike to the upright Predicta was the 1957 Teleavia from Italy. I took the following snapshot of a Teleavia on display in the design section of the French National Museum for Modern Art, part of the Centre Pompidou in Paris, France.

Despite the radical styling that endears it to collectors, the Predicta had an unhappy history in the field, causing some to dub it the "Edsel of televisions." Quality control was poor, leading to an excessive number of returns and warranty service calls. The Predicta's PC (printed circuit) boards were difficult to service and tended to crack from overheating in certain models.

Some people blame the Predicta for the demise of Philco, but that's a bit of an urban legend. Philco was a large, diverse company, and made many other console and portable TVs which were reliable and sold well.

A properly restored Predicta is certainly fun to watch. Mine has logged many hours since I completed the restoration and I love to watch that big, bright screen, which seems to float in space.

First Look

I had wanted a Predicta for years and when this nice example popped up locally, I just had to have it. The TV was "working" when I bought it, although the seller had handed it to a local repairman who did only the minimum work needed to make it play. As you can see from the initial photos, the picture was bright and clear.

That photo shows me staring into a camcorder whose output was piped to the Predicta. Broadcast reception left much to be desired, however. The vertical hold was extremely unstable, requiring careful adjustment whenever you changed stations or when the picture content changed significantly (for example, from a low-contrast to high-contrast scene).

Below are two more photos showing the TV's image quality when purchased. When not rolling, the picture was quite watchable, a good sign that indicated basic overall health. The camcorder's output tended to produce diagonal stripes, a result often seen when sending signals from a modern device to an older TV. To make decent photos in a bright room, I had adjusted the gain control differently than you'd want for normal viewing, which accentuated the "stripies."

The vertical linearity was a bit off, as well. If you look at the photo with the closeup of me, notice how the top half appears vertically stretched, while the bottom half appears squished, giving me a giant monster head with a skinny skeleton arm. When vertical linearity is correct, both halves of the picture will be in proper proportion. (The distortion also gave me bad hair and tons of wrinkles, but that's another story!)

The next two photos show the homebrew setup that I used to adjust the linearity and some other picture controls. In the first photo, you can see a video camcorder on a tripod, pointing at a printout of the classic "Indian Chief" test pattern. The output from the camcorder was piped to an RF modulator, which was connected to the TV's antenna terminals.

The next photo shows the test pattern after I had done some adjustments. Not bad, all things considered. Incidentally, you can find many test patterns on the Web. Try looking on Google or a similar search site.

The Predicta screen is encased in a clear safety cover, which is made of soft, easily damaged plastic. Mine was in pretty nice condition, with only a couple of visible boo-boos. The Philco Predicta lettering on top of the cover was still in excellent shape. Also in good condition was the oval cover for the rear of the picture tube, as well as the brass bezel and support arms which steady the massive CRT.

This is a heavy, awkward television to move around. It is best done with two people, one supporting the CRT and the other the cabinet. Be careful not to break one of the legs by setting it down at an angle.

The designers turned the chassis sideways to fit it into the slim upright cabinet. Below is a view from the left side after I had removed the curved rear cover. The main chassis sits diagonally, occupying the lower two thirds of the cabinet space. Above it is the separate tuner chassis, connected by wires and a ground strap.

The previous owner replaced a broken rear cabinet foot with a nice mahogany reproduction. After I finish the electronics, I may shoot the repro foot with a little toning lacquer to make it match the original cabinet more closely.

Below is a view of the chassis from the right side. All of the tubes can be reached from here, and the both-sides-open layout makes it possible to do certain other kinds of work on the chassis without removing it from the cabinet.

Notice the thick bunch of cables connecting the main chassis to the CRT above. The dark rectangle at the bottom, thickly crowded with components, is the infamous main PC board, which I would come to know intimately later in this project.

My initial inspection of the chassis revealed no major horrors, although some spots showed rather sloppy repair. One such case appears in the following photo.

A previous serviceman—perhaps the one who "made it work" just before sale—replaced the rectifier diodes and left them hanging in midair, along with the little capacitor, insulated with a couple of licks of electrical tape. The manufacturer certainly didn't intend these critical power-supply components to hang in midair!

Another ugly spot was the connection of the AC line cord to the chassis. This photo shows the area when I had started to remove one leg of the cord.

Whoever installed this replacement cord not only covered the sloppy solder joint with sticky black rubber goo, but in installing the cord with no strain relief, guaranteed that the joint would break the underlying terminal board. After cleaning up the mess, I would have to repair the broken terminal board with epoxy. The new line cord will include not only a fuse, but also a strain relief mounted to the chassis to avoid such damage in the future.

The Predicta contains some components that you won't see in earlier TVs. The "couplates," which we'll see later in this article, are early integrated circuits, essentially a combination of resistors and capacitors in a single, flattish case. Another is the surgistor (or "thermistor" in more modern usage) shown below. It is the black, pancake-shaped component standing on two leads near the center of the photo.

A thermistor, or thermal resistor, is one whose resistance changes as it warms up. The Predicta specs call for this unit (Sams R76) to have 400 ohms resistance when cold and 11 ohms when hot. It is installed between the AC line and the TV's string of tube filaments. This kind of component is also known as an "inrush limiter," meaning that it limits, or softens, the initial rush of current flowing to the tube filaments, helping to extend tube life.

Another effect of having a thermistor in the filament string is that it makes the TV slow to warm up. As long as you know that that's normal for a Predicta, it's not a big deal to wait an extra minute or so.

My Predicta was also missing the metal cage around its high-voltage rectifier. Although not strictly necessary for operation, the H-V cage blocks X-ray emissions and helps to keep fingers away from shocks, so I will eventually want to fabricate a new one from sheet aluminum.

Restoration

If you are new to TV restoration, I have some friendly advice for you: avoid the Predicta.

I have restored several tube TVs and I found this restoration tricky and occasionally unpleasant. The Predicta has some very finicky spots, notably the main PC board, and it has a transformerless AC/DC power supply, which increases the already significant hazards of working on a TV chassis when powered up.

The Predicta also had an abysmal reliability record in the field, meaning that you may have to cure a bevy of problems—not only one—before you get a working TV. If you pick up a non-working Predicta, follow the Boy Scout motto and Be Prepared!

This story had an eventual happy ending, but at the risk of repeating myself, there is no way that I would recommend such a project to a beginner. Before you tackle something like this, find an inexpensive (and simpler) 1950s tube TV to practice on.

Before going further, I should confess that I was mightly assisted in this project by experts from the rec.antiques.radio+phono USENET newsgroup. I'm a mediocre repairman at best, but I have learned when it's time to ask a question!

The answers and discussions from rec.antiques.radio+phono members included all sorts of useful Predicta lore, tips, and tricks. These newsgroup discussions are informative but rather long, so I have placed them at the end of this article. They are well worth reading before you tackle any Predicta project.

The Predicta is a fourteen-tube television. As it is newer than any of my other tube TVs, it uses a tube lineup that was rather new to me.

Philco created several flavors of Predicta and there were changes for various production runs, as well. It's important to start out with the right schematic if you want to restore your set. Mine has chassis type 9L37, as indicated by the red stamp seen in the following photo.

The Sams Photofact for this model is set 439, Folder 1, dated 4-59. You can order the schematic for your TV from one of the suppliers listed in our Parts page.

The first step, as always, was to clean gunk from the chassis and spray electronic cleaner into all of the controls.

My chassis was incredibly dirty. Every inch, every component, was coated with a thick layer of sticky, gummy goo, covered by dust. If I didn't know better, I would have sworn it had spent years playing in a greasy kitchen. I spent a couple of hours carefully cleaning everything with rubbing alcohol, clean rags, a soft toothbrush, and Q-tip swabs.

Inch-by-inch cleaning offers an opportunity to inspect the chassis for damage or bungled repairs. Among other things, I discovered that one filament lead for the high-voltage rectifier tube was not soldered to its terminal. Although the lead was crimped onto the terminal, it apparently had never been soldered!

I also found a couple of "cold" solder joints that had never adhered properly. Although the lead happened to be resting close enough to the terminal to make an electrical connection, the slightest jar would separate it, meaning that the TV probably misbehaved whenever someone stomped past in the room.

In the course of cleaning junk off the flyback transformer, I managed to snap a hair-thin lead. That lead is marked with the central yellow arrow in the next photo.

I succeeded in reattaching the wire, but it was a real pain. This kind of wire practically vaporizes in front of your eyes if you apply too much heat. Be careful around your flyback transformer—a replacement can be very difficult to find.

The previous photo also shows a second point of interest, marked with another yellow arrow at upper right. In my set, the white component was a 7-watt 2.7-ohm power resistor—the wrong component! This Predicta uses a 7-watt 5.6-ohm fusible resistor ("fusistor") in that spot. I know of no source for old-style fusistors, so I would replace it with a resistor of the correct value in series with a fuse, to protect the TV's B+ circuits.

Removing the Chassis

The main chassis is connected to other things with a variety of cables and leads. Removing it from the cabinet is a project in itself. Before removal, you may want to make some notes and even take photos to guide you in reassembly.

After you have disconnected the plugs and leads from the main chassis to other chassis, you can loosen the mounting bolts for three small switch boards which can remain connected. One board holds the antenna terminals and distance/local switch. Another holds the power/volume switch and contrast control. A third holds the brightness, horizontal, and vertical controls.

It is simpler to keep these little boards connected to the main chassis while you work on it, although you need to exercise care to avoid breaking connections. When I reassembled my Predicta, I found that some leads to these little boards had broken in the course of turning the chassis from side to side on the workbench.

The next photos show the chassis on my workbench. In the first view, the main PC board is at the top.

In the second, under-chassis view, notice how the chassis permits no access to the bottom of the main PC board. That board must be removed in order to rebuild it.

Removing the Main PC Board

The main PC board is connected to the chassis with six solder lugs and over two dozen wirewrapped connections. The next photo shows one corner of the board, with connecting leads still attached. (This shot was taken before I cleaned the board, needless to say!)

Near the center of the photo, you can see two wirewrap pins connected to nothing. One still holds the remains of a wirewrapped lead. These leads puzzled me at first. The TV seemed to work normally, but something had clearly been disconnected.

I would later learn that these are attachment points for the speaker wires. A previous repairman had rerouted the leads and made a direct "midair" connection between the audio output transformer and the speaker.

The previous photo also shows some of the multi-part components used in this PC board. On three sides of the 9BR7 tube you will see flat, orange components. The rightmost one looks like a wafer with four cylindrical shapes on its side. This is a "couplate," an early form of integrated circuit containing capacitors and resistors used in the vertical circuits.

At the lower left corner of the board, partially hidden by a yellow lead, you can see one of the six solder lugs connecting the board to the chassis. These must be carefully unsoldered and loosened to remove the board. There is one lug in each corner of the board, a fifth near the center, and a sixth at the left side, to which a small ceramic disc capacitor is also attached.

Before disconnecting anything, I made a drawing of the board which showed every connection and lug. This would serve as my roadmap back to Kansas, and I highly recommend that you use such a diagram rather than rely on your memory.

The next image shows my hand-drawn diagram. If you have the Sams Photofact for this TV, you can save time by simply annotating page 17 with the same information. Note that this diagram applies only to my model. I assume that the board for the 17-inch sets will have some differences. You may also notice some differences in wire colors, so make a careful note of what is present in your set.

The next photo shows how I began to disconnect the board.

The lug in the corner has been freed. I first heated the connection with a soldering iron and used a solder sucker to remove as much solder as possible. Then I reheated the connection and carefully bent upward the little pin that folds over into a slot in the lug. Be careful not to break these pins! They form electrical ground connections in the PC board circuits, as well as making a mechanical bond. If you break off a pin, you will need to restore the ground connection.

The photo also shows how I gently unwrapped each lead from its pin, using a thin needlenose pliers. Take your time and avoid breaking the brittle wires. You may find that some leads have been soldered in place during past repairs. These can still be unwrapped if you suck away excess solder and heat the pin while unwrapping.

Now the PC board has been completely disconnected. It is ready to be lifted from the chassis.

Before replacing any components, I spent a long time cleaning sticky dirt off the board, using rubbing alcohol and dozens of Q-tips. I cleaned both sides of the board, carefully inspecting the underside for any cracks or cold solder joints. Here is a view of the board's bottom.

Replacing Components on the PC Board

With the board out, I started replacing capacitors one by one. A few capacitors had previously been replaced by someone else, but I redid those, anyway, not knowing the quality of the replacements or how old they might be. Besides, the work was sloppy. Instead of removing the board, the repairman had snipped the leads from above and tack-soldered the new leads onto the stubs. I also redid a few resistors that had been sloppily replaced.

For PC board work, use a small soldering iron, not a heavy soldering gun. Too much heat can damage the delicate foil that forms connections under the board.

To remove a component from the board, I first snipped its leads from above. Then I used the iron and a solder sucker to remove excess solder from the connection point on the opposite side the board. Then I reheated the connection and gently removed the old lead stub by pushing it out from above.

Avoid using too much force when pushing out the old leads, or you can tear loose the foil, breaking the connection and making more work for yourself. If your board happens to have a broken trace, or if you happen to damage the foil by accident, it can be repaired by soldering a fine piece of wire to bridge the gap. You may need to delicately scrape the foil to bare metal to get solder to stick.

My usual practice when recapping (see Replacing Capacitors in Old Radios) is to replace one component, then try out the set to make sure the replacement hasn't made things worse. That procedure wasn't very practical in this case. In theory, I suppose you could make temporary connections to the two dozen-odd pins on the PC board and carefully lay the CRT down close enough to hook up everything on the workbench. I didn't want to pull the heavy CRT out of the cabinet, however. And, since the TV had been working before I started restoration, I expected it to work when I was done—as long as I could get everything hooked up correctly at the end.

Coached by some experts in the rec.antiques.radio+phono newsgroup, I knew in advance that one of the odd-looking couplates on the PC board was a common trouble spot and should be replaced. This component is labeled as K4 in the Sams literature.

The next photo shows the old couplate next to my homemade replacement.

To the right of the middle tube socket, you can see three empty holes in the PC board where the old couplate was installed. The photo also shows a few of the newly replaced capacitors.

The K4 couplate contains four components: two capacitors and two resistors. (The Sams schematic shows these components rather confusingly inside two separate dotted-line boxes.) My replacement was made of perf-board with components attached on both sides of the board.

Note that one of the capacitors is 2200 pf in value. The 2000-pf capacitor shown in the photo was parallelled by a pair of 100-pf capacitors on the opposite side, to achieve the correct value.

Component values are critical in this part of the TV, so you must replace components with those of exactly the same value. The capacitors used in such a replacement should be rated at 1000 volts, the same as capacitor C38 on the board. You can read more tips about replacing couplates in the newsgroup notes at the end of this article.

We're Almost Done!

The board was finished, but I wasn't done restoring this set. The Predicta uses eight electrolytic capacitors, which I replaced by disconnecting the old can units and wiring new replacements under the new chassis. I added a small terminal board to help anchor these new capacitors.

If you install new capacitors under the chassis in this fashion, pay attention to their position. The back of the speaker frame protrudes into this area when the chassis is installed in the cabinet. You don't want to cause any short circuits or create a situation where the frame smashes into a capacitor. For extra security, you can paint the capacitor with "liquid tape," a plastic material that dries to form an insulating layer.

At last, we are finished rebuilding the PC board and recapping the rest of the chassis. Now it's time to get out that PC board diagram and reconnect everything.

On advice from Bonita Lee Geniac, I didn't try to completely rewrap all the old leads. Instead, I first cleaned all the pins on the board using a Dremel Moto-Tool and a small metal brush. Then I wrapped each lead about twice around its pin and soldered it on. All of the lugs were resoldered, as well as the two resistors and single capacitor that hang off the board.

Checking all my notes and pre-restoration photos, I then reinstalled everything in the cabinet. Just when I thought I was done, I noticed a lead which had snapped off its terminal in the course of handling the chassis. After resoldering that lead, I crossed my fingers and powered up the TV for the first time in a long while.

The results were not perfect, but definitely encouraging. The TV had a strong, bright raster, but the picture was very washed out and both horizontal and vertical sync were hopelessly lost. The sound was excellent, but the volume was at full blast, unaffected by the volume control.

The audio problem was easy to fix. Looking closely, I saw that yet another lead had broken loose from handling, this one leading to the volume control. When it was resoldered, the sound returned to normal.

The video problems took more time. Preliminary checks didn't reveal anything obviously amiss, such as tubes in the wrong sockets. I started checking voltages on the PC board tubes, starting with V4, the 6AW8A video output/noise inverter tube.

How, you might ask, do you test voltages on a tube whose socket is hidden under the bottom of a PC board? The answer is to use a tube extender, which exposes the tube pins above the chassis. The next photo shows the 6AW8A tube plugged into a blue extender on the bottom right of the PC board. Extenders for other tube types are also shown on the workbench, including a homebrew extender that I made years ago when restoring my Hallicrafters SX-28 communications receiver.

The voltage check quickly showed almost no voltage on either of the tube's plates, where high voltage is expected. Appealing again to the rec.antiques.radio+phono newsgroup for advice, I got this amazingly prescient reply from Bonita Geniac.

The problem seems to be very low B+ feeding to the 6AW8. The brown lead
next to K2 indicated as #19 on Sams page 17 seems to feed from the R33
3900 7 watt under the chassis. The other end of that connects to the 280
B+ source and to R36, a 330K going to the brightness control. We know
you have 280 B+ somewhere in the set because the Horiz sweep and vert
sweep both feed off it and are working. My best guess is that you have
accidentally misconnected the brown wire which belongs on pin #19. There
is a terminal right next to #19 on the board which the cathode lead from
the CRT plugs onto called #20 on Sams page 17, it would be between the
#19 terminal closest to K2 and the one with the red wire on it which is
#21. If you reversed those two, the B+ would not be connected to the
plate circuit of the 6AW8, and the video signal/brightness control wiper
would not be connected to the CRT cathode, giving exactly the symptoms
you describe. When you look at the board, the brown wire goes to the
1.5K 2W resistor, and the lead from the CRT goes to the .047 cap. Of
course,a broken connection or short anywhere in the vicinity of the R33
3900 7 watt resistor or a problem with the board itself could still
exist. Measure the voltages at both ends of R33 and see what happens.

Sure enough, the leads had been reversed, despite my precautions. When I drew the PC board diagram days earlier, I had left out the pin to which the lead from the CRT cathode is attached with a slip-on connector. I guess I was concentrating too hard on the wirewrapped connectors when I drew the picture! In any case, five minutes later, the mistake had been corrected and the TV was playing like a champ.

If you look back at the previous photo, you will see the CRT cathode lead connected in the correct place. It is a yellow lead with green insulation near the end, located to the left of the 6AW8A tube on its blue extender. (The hand-drawn diagram which appeared earlier in this article has been corrected to show this lead in the right position.)

Final Thoughts

My Predicta has logged quite a few hours since I finished the basic restoration. It is a very watchable television, with excellent brightness and sharpness. It is also a very sensitive receiver, easily pulling in weaker stations which are hard to receive on most of my other restored TVs.

The next photo shows a live broadcast, received using a rabbit-ear antenna in my workshop.

   Movie 1

You can click on the Movie 1 link next to the photo to view a short MPG movie clip of the same material. (If you are using a slow dial-up connection, you can save a local copy of the file and play it from your computer, rather than listen to the movie stop and start as it slowly downloads. In Windows, simply right-click on the Movie link and then choose Save Target As...)

And just for fun, what better use for a vintage TV than to watch vintage movies? The following clip is from Alfred Hitchcock's Psycho.

   Movie 2

The actual picture quality is much better than what you see in these movie clips. To avoid making the MPG files too large to download, I saved them in a low-fidelity format.

Just as I was completing the project, I bought a Sencore VA62 Video Analyzer, which can be used for TV alignment among other tasks. In the next photo, the VA62 is partially visible in the background.

In the foreground is my oscilloscope, displaying a test pattern piped into the TV from the Sencore instrument. I can't claim to be an expert in using this complicated TV analyzer, but I did manage to sharpen up the alignment and achieve very precise settings for the vertical and horizontal centering and linearity.

This project was a real adventure in learning. I never could have accomplished it so quickly without all the great information from the rec.antiques.radio+phono newsgroup, especially Bonita Geniac. Even if you have restored tube TVs before, you can benefit by finding a Predicta-savvy mentor before you start pulling things apart.

Now that the electronics are working well, I have brought the Predicta back into my office, where I watch it almost daily. To avoid wearing out the fragile power switch, I turn it on and off using a power strip. As with other vintage TVs, you can also tune it permanently to Channel 3, then connect a VCR from your antenna and use the VCR to change channels. This prevents excessive wear on the tuner.

The MZTV Museum of Television has a wonderful video presentation on the Predicta. Click on 3D Interactive Gallery after you enter the website.

Newsgroup Notes on Predicta Repair

Below are edited discussions on some Predicta topics from the rec.antiques.radio+phono newsgroup. More discussions can be found by searching the newsgroup archives at Google. Search for "Predicta" and you'll learn much more.

From: Phil Nelson
Subject: weak points of Predicta TVs? 

During the next month or two, I'll get a chance to start on my Predicta TV.
It already plays reasonably well, so my main objective will be to
"do no harm" while recapping and making it reliable.

Just wondering if there are any notorious weak points that deserve special
attention.

Thanks!

Phil Nelson


From: Bill Sheppard
Subject: Re: weak points of Predicta TVs? 

Phil, here's some good Predicta sites & links -

http://www.telusplanet.net/public/napp/philco.htm
http://members.aol.com/thefiftys/html/predicta.htm
http://www.gregssandbox.com/gtech/predicta/

A little factoid: On the model with the 'totable' CRT head, they had to
redesign the video out stage with a cathode follower to drive the long
coax cable that carried the video. The cable's extra capacitance
would've smeared the signal. The K follower's low impedance overcomes
that problem.   

oc


From: George B. Shields, Jr.
Subject: Re: weak points of Predicta TVs? 

The console models are electronically identical to the Holiday Predicta
tabletop only, and not the 17" metal version.  The 17" version was actually
the best electronically.  The others had transformerless chassis which ran
much hotter than the transformer models, which leads me to the main
weaknesses of the console versions.  The added heat helped cause the early
printed circuit boards to warp and fail in time.  Furthermore, you will most
likely find the vertical integrators are weak and will need to be rebuilt
(replaced).  You cannot find replacement vertical integrators, so you'll
have to rebuild it with external  components (capacators and a diode).
Beyond that, if it still works well, consider yourself fortunate and enjoy!

-George-


From: Bonita Lee Geniac
Subject: Re: weak points of Predicta TVs? 

Well, the 17" is by far the better of the two sets electrically, but
neither one is very good. It had been widely publicized that the
Predicta was what caused the failure of Philco and its sale to Ford a
couple of years later, supposedly they had over a 100% in warranty
failure rate on those sets especially the 21" model.

If you like to cut corners, its easy to recap from the top side of the
PC board, but they usually have bad tube sockets, loose solder
connections, or other problems along with the caps. In order to get to
the foil side of the board to do any soldering, you have to remove about
25 wire/wrap connections from stakes on top of the board then unsolder
quite a few mounting points from the chassis, and completely remove the
board from the chassis. Some genius decided they could have basically a
solid metal chassis below the board.....didnt think the set would ever
need any service. Otherwise the only thing you can do is crush the old
part or clip the leads right next to it and solder the new part to the
stubs of wire left on top of the PC board. I have a wiring chart made up
showing which color wires go where because I almost always remove the
board, replace everything known to fail, then reinstall it.

The flybacks are famous for overheating and melting all the tar off
them, and are scarcer than hen's teeth and new ones are about $200 if
you can find one and the seller knows what it is for. But at least they
will work halfway decent after everything is done.


From: Ed Ellers
Subject: Re: weak points of Predicta TVs? 

The irony here is that Philco was known for some years for its "Cool
Chassis" design (in conventional B&W TVs) that was supposed to address that
problem.


From: Ken G.
Subject: Re: weak points of Predicta TVs? 

I restored a Holiday model years ago that was all original one big
problem was the old bypass caps on the circuit board .
I replaced them with exact values but had to go back & change a couple
slight value changes made a world of difference in the vertical size I
also had a schematic because mine had those striped ones .
I would make a paper chart and lay those old caps out in there original
places so you can go back & check things. I got mine fine tuned with my
cap sub box it worked just fine after that . 

I got the chance to look inside and estimate repairs for a dealer here
in town on a set like yours it had the same chassis standing on end
sorta at an angle with the tuner mounted different.

ken


From: Phil Nelson
Subject: Re: weak points of Predicta TVs? 
> I would make a paper chart and lay those old caps out in there original
> places so you can go back & check things .

Good idea! Maybe I'll make enlarged photocopies of the component diagrams
and tape the old components to them. Beats my usual scheme, which is to
throw removed components into a little Ziploc bag.

Phil


From: Phil Nelson
Subject: Re: weak points of Predicta TVs? 

> Furthermore, you will most
> likely find the vertical integrators are weak and will need to be rebuilt
> (replaced).  You cannot find replacement vertical integrators, so you'll
> have to rebuild it with external  components (capacators and a diode).

I'm feeling a little stupid here. I found the vertical integrator in the
Photofact. It is K3, apparently an integrated circuit with a little array of
capacitors and resistors in a flat case.

Most of the innards of K3 are straightfoward, but I'm not sure what to do
with the two components next to lead #3. The resistor is labeled 90K and the
other component is 4000mmf. (Is the 4000mmf component a capacitor wired in
parallel with the 90K resistor?) If this is where I'd use a diode, can you
explain what value of diode to use and how it would be connected?

Thanks!

Phil


From: Bill Sheppard
Subject: Re: weak points of Predicta TVs? 

Phil, are you intending to build a replacement for that vert.
integrator? If so, that 90K resistor should have two .002 caps, one from
each end to ground (.002 being half of 4000 pf.). At least that's the
way we always did it, and it worked fine. No diode is involved.

Those encapsulated multi-component doohinkys were called
'couplates', BTW.  There's another 'tiered' version of a couplate that
looks like a Borg ship. It goes by another name, which escapes my
memory. No doubt someone knows it. 

oc


From: Phil Nelson
Subject: Re: weak points of Predicta TVs? 

Thanks for the tip. I'm not eager to rebuild that component, but since it
was mentioned as a weak spot, it's nice to know what to do, if needed.

My plan is to do a basic recap and then see where things stand. At this
point, the TV plays pretty well, the most noticeable symptoms being some
vertical instability and taking a l-o-n-g time to warm up. The power supply
(even the pilot lamp) also seems to flicker occasionally during warmup; that
may be cured when I improve some of the previous serviceman's friction tape
work.

It looks like quite a production to remove all the innards from the cabinet.
I'm not sure how practical it will be to operate the set out of the cabinet,
although I normally do that, to check operation after each replacement.
We'll find out!

Regards,

Phil


From: Troglodite
Subject: Re: weak points of Predicta TVs? 

>BTW.  There's another 'tiered' version of a couplate that
>looks like a Borg ship. It goes by another name, which escapes my
>memory. No doubt someone know

Those were called "cordwood modules." (Presumably after the way firewood is
stacked.)

Doug Moore


From: Bill Sheppard
Subject: Re: weak points of Predicta TVs? 

I don't know if this is true of all Predicta models, but on the few I
have changed the flyback on, you have to re-use the old frame, frame
clamp, the two 'C' core pieces, and  terminal board.  The replacement
comes as only the bare coil body and 'tire', with its  tinned wires
sticking out.

In re-assembly, there's two fiber spacers (little discs
about 3/8" in dia.) that go between the ends of the cores where they
butt together. These spacers are of a particular thickness, and set the
resonant point of the core. So they are *very important*.  Then you
tighten everything up and solder the wires to the appropriate lugs, and
the rebuilt fly is ready to mount.

oc


From: Andy Cuffe
Subject: Re: weak points of Predicta TVs? 
 
Has anyone thought about ways to extend the life of old flybacks?  On a
Zenith I'm working on now, I welded the wax shell back together with a
soldering iron on low heat, filled in the holes with hot melt glue, then
gave the wax a thin coating or epoxy.  So far it seems great.  The wax
is held together by the epoxy, even when it gets so hot that the wax
starts to soften.  When I got the set, the wax had completely broken
apart and was doing nothing to insulate the flyback.  I wouldn't want to
completely coat a flyback in regular epoxy because I don't know it's HV
characteristics and it tends to get a little soft under high temp.  Is
it possible for individuals to buy small amounts of HV epoxy, similar to
what manufacturers use to pot flybacks and other HV parts?  I think
these old flybacks would last a lot longer if they were coated in
something with better HV, temperature and moisture properties than wax. 
After running it long enough to drive off all the absorbed water, I
would like to be able to dip the whole thing in epoxy.  

Andy


From: Buck Frobisher
Subject: Re: weak points of Predicta TVs? 

No technical info, but an interesting Predicta site is
http://www.mztv.com/predicta.html

It's owned by Moses Znaimer, also the owner and founder of City TV in
Canada.

regards,

Frank Johansen


Message 16 in thread 
From: Ed Ellers
Subject: Re: weak points of Predicta TVs? 

>"It's owned by Moses Znaimer, also the owner and founder of City TV in
>Canada."

That was the first UHF station (not counting translators) in Canada, so I
suspect Moses has a particular attachment to that one Predicta with the
built-in UHF tuner.


From: Crazy George
Subject: Re: weak points of Predicta TVs? 
 
Another observation:  Philco sync separator circuits often used a high
value 1/2 watt, 1+ meg plate resistor which operated within dissipation
ratings for dc, but the pulses ate them up.  I replace them with a couple of
half the original value, 1 watt film resistors in series, and that seems to
stop the problem.


From: Bill Sheppard
Subject: Re: weak points of Predicta TVs? 

>The other observation: Philco sync 
>separator circuits often used a high value >1/2 watt, 1+ meg plate resistor which 
>operated within dissipation ratings for dc, >but the pulses ate them up. I replace 
>them with a couple of half the original 
>value, 1 watt film resistors in series, and 
>that seems to stop the problem.

Ditto for the plate load resistor of the vert. oscillator. Not just on
Philcos but most all makes.

oc


From: Scott W. Harvey
Subject: Re: weak points of Predicta TVs? 
 
I repaired one of these once that had been used in a museum display on
early television. They played an endlessly looping videotape of old
television clips on it for something like 12 hours a day, 6 days a
week.

What I found was an inordinately large number of resistors that had
fallen out of tolerance, probably owing to the heat and cramped
quarters inside the cabinet. These sets do run pretty damn hot. The
picture on yours appears to be better than 90% of Predictas I've seen
in the flesh, so I'd bet it dosen't have a lot of hours on it.

-Scott


From: Phil Nelson
Subject: Re: weak points of Predicta TVs? 

> These sets do run pretty damn hot.

Maybe I should install a tiny fan inside the cabinet. After the first couple
of hours, I noticed it had dropped a couple of new blobs of flyback wax. At
that rate, the remaining wax won't last long :-)

Anybody know where to find a small and REALLY QUIET fan? I got a little
squirrel-cage type fan at Radio Shack to cool a prized piece of audio gear,
but it's noisier than I'd like.

Phil


From: Buck Frobisher
Subject: Re: weak points of Predicta TVs? 

one, maybe two fans as used as CPU coolers in a computer?


From: Stewart Ono
Subject: Re: weak points of Predicta TVs? 

Try running an 220 V impedance protected fan at 120 V. Fan speed is halved,
but will still move air and very quietly, too.


From: Bill Turner
Subject: Re: weak points of Predicta TVs? 

STEWARTS MENTION ON RUNNING A FAN ON LOWER VOLTAGE JUST REMINDED ME THAT
I HAVE A 208 VOLT FURNACE BLOWER RUNNING ON 120 VOLTS TO CIRCULATE THE
HEAT FROM AN UNDUCTED GAS FURNACE AND THE COOL OF A TWO TON AIR
CONDITIONER AROUND MY GARAGE.  IT'S ABSOLUTELY NOISELESS YET MOVES A LOT
OF AIR. I HAVE TO REMEMBER TO TURN IT OFF WHEN SPRAYING.

disregard caps, visual problem          
Bill Turner WA0ABI


From: Jim Millick
Subject: Re: weak points of Predicta TVs? 
  
Phil, you may be able to adapt something from PC Power &
Cooling.  They have a number of products that are *very*
quiet.  Check out:

http://www.pcpowerandcooling.com/products/cooling/index.htm

I have one of their power supplies, and it is super quiet.


From: Phil Nelson
Subject: Re: weak points of Predicta TVs? 

Good tip. They have a quiet 80mm fan on sale for $9, and shipping via UPS
ground is free. I ordered two!

Browsing an audiophile newsgroup, I discovered another trick. Wire two fans
in series and you'll move about the same volume of air with even less noise.

Looking at the pedestal cabinet, I noticed a couple of other things. The
rear cover has air vents only at the top. The front louvers are strictly
decorative; there's a solid speaker board behind them. When placed on a hard
floor, I suppose there's enough of a gap to admit cool air at the bottom of
the cabinet. But when you place it on a carpet, the whole thing sinks into
the shag, creating a hot little coffin with no ventilation except at the
very top and rear. I think I'll find a board to stand it on!

Phil



------------------------
From: Phil Nelson
Subject: removing main printed circuit board in Philco Predicta &#^$%@! 

Can someone share the secret for removing the main printed circuit board
from the chassis in a Predicta TV? I have the barberpole model, if that
matters (I suspect not).

I have loosened the four soldered chassis lugs on the corners of the board,
removed two resistors on one side and removed a little ceramic capacitor and
loosened the chassis lug that it was soldered to. The board is loose at all
those points, but won't come free. It feels like it is still fastened to the
chassis at some point in the middle of the board. Peering under the opposite
side of the chassis, I didn't see anything obvious to loosen. What's the
deal?

I'm hoping that with the aforementioned stuff loosened, I will be able to
scoot the board away from the chassis far enough to replace a couple of
capacitors whose "underneath" leads can't be reached from above.

Not having fun yet :-(

Phil


From: Bonita Lee Geniac
Subject: Re: removing main printed circuit board in Philco Predicta &#^$%@! 

You wont be having fun anytime soon on this one. One of the least
serviceable designs of its time. There are more than just four soldered
chassis lugs on the board, presuming that you are talking about the main
PC board with the vert, horiz, video amp and audio stages on it. IIRC
there is at least one more in the middle, plus 29 connecting leads which
are wire wrapped on terminal lugs above the board.  Then the board will
come completely off the chassis. If you are trying to cheat and only get
one edge up enough to replace a couple of caps, you might only have to
remove the wire wrapped leads from two edges of the board.  But IMO this
is a total waste of time. Predictas are notorious for bad solder
connections where the tube socket pins and other components connect, so
you are far better off removing the whole board, checking and
resoldering all the marginal connections. Sometimes the tube sockets for
the vert and audio output tubes are weakened by heat to the point where
they either disintegrate or lose the tension on the contacts. There are
also a couple of resistors around the video amp circuit that go way off
value.  Dont forget to make up a replacement for the standup couplate in
the vertical output circuit (K4 in Sams), those are apparently paper
caps in there because they are always leaky and affect vert linearity. 
When you replace the board, use a Dremel tool with a small grinding
stone to clean the wirewrap terminals so they will take solder. Wrap a
couple turns of the lead around the terminal, solder, then clip the
excess. I have a cheat sheet showing which wire color goes to which
terminal when replacing the board.
Everyone hates to work on these sets because of the fact that Philco
chose to mount the PC board above a basically solid metal chassis making
the foil side totally inaccessible without removing the board. Wonder
what genius thought that up, they must have been thinking the set would
never need repair under warranty and didnt care whether or not it was
easily serviceable after it was out of their hands. There is no easy way
to operate the set with the board lifted off the chassis because you
have to complete the 5 or more ground connections as well as extend the
29 leads connecting to the board. This is one time where those Pomona
socket adaptors that allow checking tube pin voltages from the top side
are an absolute requirement.


From: Phil Nelson
Subject: Re: removing main printed circuit board in Philco Predicta &#^$%@! 

Thanks for the tips, Bonita. I did eventually find the fifth lug in the
middle of the board, concealed under a replaced capacitor. Loosening that
didn't give enough slack to reach under to the bottom of the board, so I
guess I am doomed to go ahead and remove the 2 dozen+ wirewrapped
connectors. A cheat sheet sounds like a necessity for getting everything
reconnected again. I'll label each lead with masking tape and draw a picture
as I go.

While I'm at it, I'm tempted to replace every R & C on that blasted board. I
thought a Hallicrafters SX-28 was a pain to recap, but . . . sheesh! I had
promised myself last year around this time that I'd have this set rebuilt in
time to watch the World Series on it. At this rate, it should be ready in
time to watch "It's a Wonderful Life" around Christmas.

Regards,

Phil


From: Phil Nelson
Subject: Re: removing main printed circuit board in Philco Predicta &#^$%@! 

> Dont forget to make up a replacement for the standup couplate in
> the vertical output circuit (K4 in Sams), those are apparently paper
> caps in there because they are always leaky and affect vert linearity.

Well, I got the board off and replaced the Cs as well as the K4 array.

After I finished that, I thought, "what about K2 and K6?" Do they also
contain paper caps? The outward appearance is like K4 -- like a row of
ladyfinger firecrackers dipped in wax. Are these also known troublemakers?
Or should I not bother?

Regards,

Phil


From: Bonita Lee Geniac
Subject: Re: removing main printed circuit board in Philco Predicta &#^$%@! 

Havent had any problems ....yet.... with either of those. If it works,
probably best to leave it alone. Had a couple sets with K3 bad a few
years ago, and have had a few sets with C43 silver mica 390pf in horiz
osc leaky. Possibly some of the caps in those couplates could be tubular
ceramics, but the K4 couplate has always had big problems with the
1500PF between term 1 and 3, use the same kind of .0015 @ 1KV or better
as used for C38.  If you want to make a K3, the weird cap/resistor
symbol is actually a resistor with the silvered cap deposited on top of
the resistance element in such a way the capacitance is distributed
across the entire resistor. Zenith made a stand alone component with
basically same construction, dont remember the part# at the moment but
has to be NLA by now unless you had a used one saved from a junker. But
you can use two 47K resistors and three separate caps totaling about
.004, like the vert integrators used in just about every other brand of
set. Have to stay pretty close in values because of time constants. Have
notes also referring to vert lin problems with certain brands of 10DE7,
with Tung-Sol being the best, some Sylvania OK. Also most of the
Predictas suffer from thick bright vert lines in the upper half of the
picture which give the appearance of retrace but are not retrace.
Actually caused by new signals on previously unused (in 1959) lines at
top of picture. They are not present all the time. Mods to blanking not
effective in removing. It has been suggested that altering the time
constants in the sync separator might reduce the lines. That info came
from a network chief engineer.  Seen mainly on network programming with
VIR signals that are often not present on local broadcasts (news,
commercials). 
After working on this set for a while you will understand why Philco did
not stay in the TV business for much longer after designing this
set.....just a couple years later Philco was sold to Ford.


From: Bill Sheppard
Subject: Re: removing main printed circuit board in Philco Predicta &#^$%@! 

Bonita wrote,
>If you want to make a K3, the weird 
>cap/resistor symbol is actually a resistor 
>with the silvered cap deposited on top of 
>the resistance element in such a way the 
>capacitance is distributed across the 
>entire resistor.

I used to make a replacement for those with a resistor
and two caps of equal value. The caps went to either end of the R, with
their other leads tied together as the middle pin (ground). Don't
remember the value of R, but .001 springs to mind as the C's. Can't
swear to it though. Been a lotta years. 

Bill (oc)