Actually Eric you can use a back silvered mirror for the top mirror. You just have to use the thinnest glass mirror you can find, 1/8" will work fine. Use a backing board to make it the same thickness as the original.

It won't be perfect, but it will give you more brightness than the old one.

Chuck

Or... you can buy front surface mirrors online, either cut to fit or have your local glass shop cut it for you. You should have the spherical mirror resilvered for best results. This company does good work at reasonable prices:
Spectrum Coatings:
1165 Ring St. Deltona, FL 32725
Phone: (386) 626-9782
Contact Person: Paul Zacharias
[email protected]

Hey John, didn't you restore a Philco 48-2500 projection TV?
How much of an improvement did a resilvered spherical mirror
make over your old mirror? I ask this because the spherical
mirror in my 48-2500 is not perfect but it looks pretty good.
Mine does though have some places in it that you can see straight
through though.

Carl

My mirror in my 48-2500 was in very poor condition, so having it resurfaced made all the difference. However, dummy that I can be, I attempted to clean the curved mirror in the lid. Disaster! The top coat on that mirror is a multi-coat lacquer coat filled with micro-spheres which act to provide optical gain.

But I have restored several RCA projection sets from the late 1940s, and if you want to achieve optimum optical resolution, resilvering the spherical mirror and replacing the flat front surface mirror is the way to go. These sets can provide quite acceptable bright (though very directional) images when operating at peak performance. Of course, of "close is good enough", then the mirrors you have may be tood enough.

The Spherical mirror in my set is in very good condition, surprising considering the rest of it.

I'm curious as to what an RCA Spherical Mirror looks like.
Do you have any photos?

Carl

I don't have a photo at the moment but it pretty much looks just like the one in the Philco, I think it's a bit larger due to the larger CRT.

First light!
 

Finished recapping the i.f. chassis tonight so I decided to give it a full power up, everything's connected except the Audio Amplifier, that is a separate unit and I don't think it needs to be in place for the set to work.

I put the CRT in a plastic container, must be High Dielectric since it didn't arc through. :yes:

First try I got a line on the screen followed after a couple seconds by a shutdown, probably the protection circuit kicking in to prevent a phosphor burn from lack of sweep.
I did a little poking around and didn't see anything obvious, then it occurred to me to check the 5U4's in the power supply (there are three of them!), sure enough one of them was stone cold.
I had been having some trouble with them lighting up before because of bad or dirty sockets, I wiggled it a little and it came on so I gave it the juice again, now I have a full raster!

The focus looks terrible and I have no control of the brightness, it's the same no matter what control I turn, I do get some flashing when I turn the tuner (one channel in particular with the Agile Modulator broadcasting) so I think it's passing a signal all the way to the CRT, I just can't see it because it's washed out, can't hear it either because no amp hooked up. :scratch2:

Anyhow I've had enough X-Rays for tonight, at least it powers up now so I just have to figure out the rest of the issues and finish the cabinet.

I talked to an old-timer TV tech in Tacoma about these RCA-type sets about 20 years ago. He said his hair fell out after working on one!

LOL, he probably pulled his hair out after working on one of these.
I intend to put the CRT in the barrel before I do any more serious work on it, I just had it on for a couple minutes to see if it would run. I put the lid on the HV cage at least and kept my distance from the CRT.

These sets have no protection circuits to shut them down.
I suspect that tube socket is shot.RCA used some very cheap sockets.
You could have an hk short in pix. tube. Check your voltages from video amp to brightness control, and, with socket removed, voltages on cathode, and, first grid pins. See if brightness control varies the B+at that pin.
You should see variation.
If the picture tube is bad, the good news is they are fairly common.
Bill Cahill
5TP4

I'm curious because I have a Philco 48-2500, but where are the
X-rays emitted? From the face of the CRT or all around?

Carl

Whoa there Eric! There are three ways to avoid radiating yourself.

1) Measure the distance from the top of the light barrel to the center of the mirror and then to the center of the screen in the cabinet. Mount the CRT in the light barrel on a table approximately that distance from your ceiling. If you are sitting very close to the light barrel, I'd suggest adding scrap sheet metal between you had the barrel. Don't forget to ground both the scrap metal and the barrel.

2) Mount the CRT in the light barrel and jury rig a mirror at a right angle to reflect the image off the wall. or operate the light barrel on its side and project directly on the wall. Determine distance by experimentation. Don't forget to put a metal shield on the mirror side of the barrel when operating this way.

3) Disable the voltage trippler. Remove the 2nd and 3rd 8016's and feed the HV directly from the plate cap of the second now-removed 8016, to a standard high voltage 50-53 degree 5 inch test CRT. You will probably have to shim the yoke. The test tube is close enough to the sweep angle of the 5TP4 to not cause a problem, and any X-ray generation will be minimal at this much much lower HV.

James

This option sounds the best for longer term testing and diagnosis, safer for me and the 5TP4.

I would think it should be fairly safe inside the barrel, it's thick Aluminum and the face of the CRT points downward against a thick, Aluminized mirror.

When I was testing my Philco 48-2500 I pointed the CRT away from me and viewed it in a mirror, later I installed it in the barrel, in any case I avoid being around it as much as possible.

I'm assuming most of the X-rays would be coming out the face of the CRT, the glass is very thin on the face of the 5TP4 and the TP-400 and possibly not Leaded.

Does anyone have any hard facts on the amount of X-rays produced by the 5TP4 operating at 28kv? Guessing the third HV rectifier tube will also be putting out some rays at that voltage?

This set uses three 1B3's by the way, not 8016's, maybe a different version?

Bill, the CRT tested good, no shorts, probably something in the circuit.

I thought it had protection because it would operate for a few seconds with a narrow line and then shut down, it did this several times, possibly it just didn't have enough B+ to keep running?

The 8016 is just the developmental number for the 1B3. Same thing.

At <= 30KV, the X-Rays produced are relatively soft, and the glass of the mirror and the metal of the barrel are effective in stopping them. And if you keep the covers on the HV cage, likewise. But caution is advised. And distance is a good protector.

I bought three WWII-dated JAN 8016's on ePay some years back. Anyone know what piece of gear they went in?

I removed the second 1B3 and hooked a jumper to the output of the first, then I installed a 5AXP4 test CRT, turns out it works very well this way.

I still have no control over the brightness but the "Picture" (Contrast) control does work, possibly the Brightness Pot is bad.
The Sync is all over the place but I was able to get it to hold still long enough to snap the picture below.

Unfortunately as the set gets hot the picture fades out, also I noticed the image is negative, not sure if the 5AXP4 has it's Grid and Cathode wired differently than the 5TP4 or if it's a problem with the chassis.

I haven't tested any of the tubes in the i.f./Vertical sweep chassis but I did swap out most of the relevant ones with no improvement, there are probably some drifted resistors somewhere.

I wanted to take a look at the brightness issue before I went to bed so I studied the schematic from the brightness control to the CRT and I found a cap I overlooked.

I didn't pay much attention to it because it was the Domino style and I was probably thinking it was a Mica, however the schematic showed it to be a .05@600 and most likely just a common paper cap, why they used this one odd style I don't know, maybe it was supposed to be better quality.

It's cap# 58 on the Sams, between the 6V6 Video Output and the 6AL5 DC Restoration tube, from there it goes to the Grid of the CRT.
As soon as I turned it on I could tell it was better, not only does the video and brightness work now but the sync is fixed too.

I tried it with the 5TP4 also but still with only 10kv on the Anode, the tube works but I can't get any focus with so little HV.

Sams capacitors C58 (which goes between the plate of the video output and the grid of the CRT) & C59 (which goes between screen grid of the video output and the cathode of the DC restorer) are called C168 & C171 by RCA and RCA sez:

RCA part # 72996 Capacitor-Moulded paper, .05 mfd., 600 volts (C168, C171)

(Yep! They must have been conservative 'cause they used the old spelling of "molded" )

These RCA projection sets were notorious for blooming issues with high voltage regulation, and I've heard of stories of service men intentionally disabling the DC restoration to lessen focus shift and blooming as the HV drifted when the sets got older. It seems like cutting off your nose to spite your face, but it did allow a failing CRT to remain in service a little longer. Once people started watching TV in more brightly lighted rooms, the DC restorer went the way of the dodo bird as designers no longer saw any benefit.

I suspect the HV issues had more to do with the design of the early 8016's than with DC restoration.

The RCA 630 had a similar circuit, except the 630 used a 6K6 instead of a 6V6 for video output, and it used a normal tubular .05 mfd 600 volt for these two caps.

What does "blooming" look like?
I've heard this term but never really knew what it means.

Thanks

Carl

If it's being used the way I use it, it's when the picture gets larger due to increased brightness.

'Blooming' occurs when the high voltage drops signifigantly. Static attraction from the front of the CRT decreases, allowing sweep angle to increase or "bloom". The raster progressively dims and goes out of focus as it blooms.

The most common cause is a weak HV rectifier. Or excessive CRT beam current can lug the HV supply down (eg., from the brightness control being turned too high).

I feel like I'm getting off-topic (sorry), but thanks for that explanation. That might actually help me with the blooming on my set. The 1K3 rectifier was dead when I got the set, so I replaced it with a 1B3 I had lying around, thinking it would be 'close enough'. If it's outputting on the weak side, that might explain the weird blooming pattern I've been seeing lately.

My 1949 made 8PCS41 cabinet sticker calls for the 8016.

Between it and the other 1949 9PC41 I had one 8016 (probable replacment) and two RCA branded 1B3/8016. The rest were replacment 1B3.

Usually interchangable, but:

8016 = PIV 10,000 max, Ip = 7,6 max ma, average 2 max ma (1942 data)
1B3/8016 = PIV 30,00 max, Ip = 17 max ma, average 2 max ma (1949 data)
1G3/1B3 = PIV 33,000 max, Ip = 35 max ma, average 1.1 max ma (1965 data)

As the tubes improved the PIV increased, the short-flow current increased, but the average-flow current decreased. I would not put a 1G3 in an RCA projection set.

James

Did some resistor checking tonight and replace a few high ohm resistors that had drifted out of tolerance. Not badly out but like a 2.2m that measured 2.8m, 1.0m drifted to 1.4m, it seems to have improved the sync and vertical lock, they were all in those sections.

The Contrast control was having no effect except a slight increase in Contrast all the way at one end, I opened up the Pot and found this: http://vintagetvsets.com/images/8pcs41/contrast-pot.jpg

It's a 1000 Ohm Pot and it's stacked with the Brightness control, according to the schematic it's not the same as used in the 630, I had hoped it might be since I have some spare parts for one of those.

Hopefully I can find a good Carbon in something else and transplant it to this control.

Here's 4 pages from the RCA HB-3 Tube Manual showing the specs. for the 5TP4 CRT.
The limiting factor for this tube is that it can only dissipate 5.4 watts. This is determined by multiplying the Ultor operating voltage ~~27,000 volts by the beam current ~~200 microamps.

If this value is exceeded for a long time the heat developed can crack the faceplate. This results in what RCA laughingly calls a "catastrophic failure" of the CRT.

You can measure the beam current by connecting a 1000 ohm resistor in series with the cathode lead to ground and measuring the DC voltage across it. 200 microamps [0.2MA] would show a voltage of 0.2 volts.

It is always gratifying to see these projection sets restored because they represent an important step in the development of television.
Your restoration is specially interesting because you have done so much work
and very well to make this set look and operate like new again. Congratulations.

Don't forget the basics.
 

I have spent hours over a period of days trying to figure out why the Audio Amp in this set wasn't working, it was dead silent except for a very faint bit of static if you touched a screwdriver to the plate of the output tube.

I poured over the schematic, checking wiring, checking resistors, checking voltages, convinced I'd wired something wrong, I tried jumping the field coil in the speaker and using a PM speaker, I tried different sources and not a peep, voltages all looked good enough that it should be working but it wasn't!.

I had subbed the 6J5 where the signal comes in but I didn't test the 6F6 output tubes because no way could they be dead enough for it to be completely silent.
They had a nice getter and looked fine, anyway it's a push pull amp so if one is bad it'll still work on the other, and no way could they both be dead enough to kill the whole thing, could they?:dammit::yes:

Both 6F6 output tubes were completely dead, heaters lit, no shorts, no apparent gas, just absolutely no emissions at all. I couldn't find any 6F6 tubes handy so I stuck the first somewhat similar audio tube I could find in the amp, a 6L6 and viola, it worked fine on one tube. I dug up a couple 6V6's and plugged them in and the Amp is alive, of course now the TV chassis is somewhat dead waiting on a contrast control but one thing at a time.

I've had 3 or 4 of those amps, and I've never seen one where the green power resistors didn't look like they'd run hot. I finally got another 8PCS41 last year, and it came with a newer pair of 6K6's in it. Got a fair amount of audio while the plates were glowing! I'm assuming the owner who had it serviced used it this way for years.

One of the big green resistors was open, I don't think it was originally since they were all running hot to start with so maybe I blew it open while tinkering. I subbed it temporarily with a 2.5k @ 5 watts.

I'll have to look for some 6F6's, not sure I have any.
Will the 6V6 sub it on a permanent basis or do I need 6F6's? I tried a 6L6 also and it worked.
I'd like to get some in an ST bottle like it shows in the Sams picture.

Didnt hurt my 37 Delco subbin the f6 with a v6....

SR

I believe that a 6V6 is a good substitute for a 6F6. The heater current of the 6V6 is .45 amps vs 6F6 which is .7 amps. So, you can use two 6V6s until you get a pair of 6F6s or keep the 6V6 in there.

They have the same 315 volt maximum plate supply voltage, but the 6V6 grid bias at maximum rating is only -13, while the 6F6 is -22, so there's less danger of it running too hot when biased for a 6F6. Values are similarly safe for push-pull configuration...

BTW, is there -21 volts on the Grid #1's?

Yes, all the voltages on the 6F6 sockets were in the ballpark.

Good! I was looking on the ETF copy of the schematic, and it looks like some of the green resistors aren't powered directly, but go into the interconnect plug, but I haven't traced it out yet. Very confusing, since I've never seen both radio and TV audio connected to the lone amplifier simultaneously!

This set doesn't have a radio, and the Amp can run independent of the TV chassis & power supply, it does need the speaker due to the field coil and what appears to be a choke or some type of hum bucking coil built into it. The Sams isn't real clear on that part.
The three green resistors seem to be strung is series on this chassis, using unused socket pins to mount them.
The main power and lid switch switch are connected to the Audio chassis, there is a power socket to plug the power supply chassis in to. The HV cage also has an interlock with the power supply chassis but it's lust a loop at the HV cage, the PS won't fire up unless the HV cage and cord are in place.

I didn't think the Sams had an underside photo of the Audio chassis but I just now found it.

Lots of different cords on this one, it is a bit confusing. I've been running it by using separate cords for everything.

I've been working up an interest in finishing this project, or at least getting it all back together.
Getting it back to it's original factory state is out of the question, my goal is just to make it solid and presentable, to that end I've been working on fixing up the cabinet so I can get the chassis off my bench where it's been sitting the last couple years.

I sprayed the interior with some "Camoflauge" paint, this is to hide the water and Mouse stains and make it look a little nicer, yeah I could ahve used black or something darker but i wanted it to look less dingy.
I gave the outside a rubdown with some cherry stain to make it look better, I'll probably use toner on the hardwood trim to cover up it's many defects, the rest will get stained and lacquered eventually.
It's missing about a three inch wide strip of veneer from the left side, I'll patch it up and not worry too much about a perfect blend.

I've got it basically put back together, most of the hinges and screws and such, I had to use longer screws in most places to get a good bite in the dry wood.

Maybe soon I'll reinstall the guts and see what it'll do.

It looks fairly good. I've seen some pre-war RCAs with gray interior paint, so it is not horribly unoriginal looking with that cammo paint.

I also call it livable. But, you really need to rebuild it electrically. These sets get a lot of shorted electrolytics, and, shorted paper caps.
I think it's worth saving.