Zenith G2952 "St Regis" porthole restoration
 

A customer dropped this off last year and I'm finally getting around to it. Apparently, it had been rented out as a prop for years and is a little rough.


Worse issue cosmetically is brown enamel paint was slopped on the top and upper sides.

Also need to track down the inner power/volume knob. It came with an Admiral knob stock on!

https://live.staticflickr.com/65535/...e758b7e0_c.jpg

https://live.staticflickr.com/65535/...5603a520_c.jpg

https://live.staticflickr.com/65535/...5a714ef4_c.jpg


29G20 chassis with power supply down below.
Partial recap on the power supply. Main chassis appears to be 100% original.
Curious that is has the tuner on the left.
https://live.staticflickr.com/65535/...94562c7a_c.jpg

https://live.staticflickr.com/65535/...39f60cf9_c.jpg

https://live.staticflickr.com/65535/...36125656_c.jpg

https://live.staticflickr.com/65535/...267c1f3e_c.jpg

I expected the 16EP4 to have gone to air and secured an all glass 16DP4. However, after letting it cook a while, the EP4 came to life.
https://live.staticflickr.com/65535/...de6d8869_c.jpg

The chassis is absolutely pristine under a thick layer of dust.
https://live.staticflickr.com/65535/...f3a1aacd_c.jpg

A few original tubes still in the set.
https://live.staticflickr.com/65535/...8b23bb5c_c.jpg

Every single power resistor is open! Dropped $25 for 7 new ones.
https://live.staticflickr.com/65535/...e719014d_c.jpg

Very roomy under the chassis and easy to recap.
https://live.staticflickr.com/65535/...c1f67d27_c.jpg

I'll finish detailing the chassis later. Next up, first power up attempt! I love that Zenith used a snap conector on the HV lead that works with a conventional CRT.
https://live.staticflickr.com/65535/...e7b8f6f3_c.jpg

First light!
It took a while to realize there's a, RCA jack in the back for a pilot lamp interlock. It needs to be shorted for the lamps to illuminate. I assume it can get annoying while watching the set to have those on.
https://live.staticflickr.com/65535/...d00348a4_c.jpg

At full power with 5U4s installed, I got a raster!
https://live.staticflickr.com/65535/...b057faf6_c.jpg

Height increased
https://live.staticflickr.com/65535/...d1309e75_c.jpg

After a lot of control tweaking, a stable image was achieved
https://live.staticflickr.com/65535/...9c016a2c_c.jpg

Hmm. I think the huge focus coil is messing up my little 5AXP4 CRT.
https://live.staticflickr.com/65535/...41a9f74f_c.jpg

Here it is with focus coil unmounted. Rather washed out even with brightness turned all the way down. Still have 10 electrolytics to replace on the main chassis.
https://live.staticflickr.com/65535/...e8a4436b_c.jpg

Congrats!

Since you mention “5U4s”, I have always wondered, is there really a big dif in the 5U4/5U4G/5U4GB, and so on.

This site seems to list differences, but does it matter in a TV?
https://300guitars.com/articles/rect...ge-drop-chart/

My set has the OEM RCA 5U4-Gs, they still work but are old and a bit worn, I can see a bit of the heater material has come off and is floating around in the tube, to get EXACT replacements will hurt a lot cause of the insane prices they want for them, thanks to the audiophile market.

$170 for a NOS RCA 5U4-G is insane!
The GB has a larger voltage drop, 6-7 volts and has a much less crazy price, will that drop of 6-7 volts in the G vs the GB really matter much?

The GZ37 has an even better voltage drop rate at 37v, but it's price is even MORE insane for NOS, WTF!

And there is also the 5AR4 / GZ-34 , not so over priced, but with a voltage drop rate of 10v, may be too harsh.
So it seems is is 5U4-G and pay, and pay A LOT for them, or 5U4-GB, and have slightly lower voltages.
To me it makes no sense for the prices to be so damn high.

No, it will not make any difference in a TV.

You can throw sense out the window when it comes to tubes used in audio gear.

Pretty much all of the components (caps, resistors, tubes etc.) have a wide operating window. Plus, there's no voltage regulation so all the voltages vary with what's coming out of your outlet. That's why you have so many controls to compensate.

Absolutely! Vintage and new tube amp audio have gone off the charts in the past couple of years. The turntables and tuner/amplifiers we were so proud to have in the 1970s are commanding outrageous prices on auction sites. A basic, entry level Marantz tuner in good shape will fetch anywhere from $1,500 to $2,500. The higher end Sansui and Pioneer stuff is more insanely priced. I know they were all solid state and not tube gear but it is an indication of how all old audio platforms have rocketed up in price.

“The GB has a larger voltage drop, 6-7 volts and has a much less crazy price, will that drop of 6-7 volts in the G vs the GB really matter much?”

But the drop through the GB was measured at a higher current! I suspect the drops are nearly the same @ the same current. :scratch2:

jr

findatube.com shows new 5U4G for $24, used $10. Who knows if they're in stock. Ebay or any audio/guitar amp site is about the last place I'd look for a NOS tube.

If there really is no difference that matters then, I do have a pair of NIB NOS Raytheon 5U4GBs that I was keeping for other newer sets, I just find it nuts that they have such a markup for what is more or less the same tube 5U4G/5U4GB.

And insane that my Sansui 9090 amp would go for over $4000 now!:scratch2:

Anything 5U4 based will replace a 5U4G, but the opposite isn't always true. A set that specs a high current rated 5U4 variant may not be happy with a lower current G... At least long term.

Did you do an eBay search and find that price? The prices are crazy. Vintage electronics repair businesses are overwhelmed with restoration work.

Exactly, I took a peek on evil-bay for what restored amps like mine were going for, and it's crazy, mine is not “ restored” but is working, could use a rebuild, it too is something I saved from destruction when I saw it in my HS electronics class. Weighs a ton, so you know it's built well!

Started work on the cabinet. Plan is to refinish the top and touch up the rest.

https://live.staticflickr.com/65535/...80ab1174_c.jpg

Underneath all the crud, the veneer is in good condition.
https://live.staticflickr.com/65535/...5e62abe9_c.jpg

The button below Zenith is what operates the dial lights.
You won the lottery on the 16EP4! Those are very difficult to find.
Curious if you determined that there is enough room for the 16DP4?

Thanks. I missed the button switch.

Yes, the 16DP4 fits. They are the same size and deflection angle. 16DP4 is a recommended replacement with the 16EP4.
Room isn't the real challenge though.
The HV metal bar on ceramic insulators needs to be removed and replaced with something that can support the glass CRT at the right height so everything lines up.
I suppose something could be fabricated from wood. Then you'd need to rig up a strap the hold it down.

That aside, I suspect the 16DP4 is even harder to find than a 16EP4.

I bought an NOS Rauland 16EP4 off the 'bay years ago, and was shocked what a poor quality tube is was, physically & electrically. The faceplate had a very significant warp to it, good getter flash, but the tube tested completely dead. Original box, warranty card, the works. Shocked that Rauland would even put their name on that POS.

Sounds more like a bait and switch by the eBay seller. I could be wrong but...

Slowly making progress on the cabinet in this hot, humid, rainy summer.
I got really lucky on the sides. The slopped on paint easily sanded off and the finish underneath is in good condition.

I lightly sanded the old finish to remove the surface oxidation and alligatoring then over-sprayed with semi-gloss lacquer

https://live.staticflickr.com/65535/...3dc966b0_c.jpg

https://live.staticflickr.com/65535/...64d65b94_c.jpg

https://live.staticflickr.com/65535/...7fa52a2f_c.jpg

https://live.staticflickr.com/65535/...9fd4eb01_c.jpg

That leaves the trim around the top and the base.
Or maybe I'll just turn it into a dog bed?
https://live.staticflickr.com/65535/...472f6d4b_c.jpg

Flipped the cabinet over and was able to get the speaker board out with out too much trouble.
So much easy to work on the base woodwork now.

It's in quite good condition for a set that was kicked around.
https://live.staticflickr.com/65535/...a9240095_c.jpg

https://live.staticflickr.com/65535/...f01ce16e_c.jpg

Just waiting for the weather to cooperate and I'll touch up the front and base.

https://live.staticflickr.com/65535/...3aa784bc_c.jpg

https://live.staticflickr.com/65535/...665acb4d_c.jpg

You are wrong

Well, sorry about that, John.

Finally got a break in the hot humid weather and was able to finish touching up the cabinet after working tonight.

These were taken at twilight so not the greatest quality photos. Miles better than the muddy, painted finish I started with and it's mostly original. Only the top and trim were refinished. The rest only touched up.

Used Mohawk Tone Finish Mahogany on the trim.
https://live.staticflickr.com/65535/...a31c3c5d_c.jpg

https://live.staticflickr.com/65535/...020e859f_c.jpg

https://live.staticflickr.com/65535/...3f252707_c.jpg

Now there is one thing I'm missing - the volume/power knob.
Does anyone have a spare?

https://live.staticflickr.com/65535/...58159307_c.jpg

This was back in 2008, when older tubes would pop up more frequently.
Seller auctioned a warehouse inventory of tubes. I got the 16EP4, also a 12UP4, 16GP4, and a 19AP4, all NOS in original cartons with paperwork.

Just about done with the recap and have some odd issues with the image.
Do not have full width or height.
Image is crushed on the left a bit.
Cannot turn the brightness down very much
Image inverts if I increase brightness or contrast too much

Now that was with the 5AXP4 CRT. So, I popped in the 16EP4 for the first time to see if it had the same issues. It works which is great and has the same issues.
That;s good beacuse that means I can troubleshoot with the little CRT

https://live.staticflickr.com/65535/...8bc89f22_c.jpg

https://live.staticflickr.com/65535/...d082d3db_c.jpg

Success! The 33K resistor between the brightness control wiper and CRT cathode was measuring close to 500K. Also, the pairs of 100 ohm and 150 ohms resistors on the dual 6BG6 horizontal output tubes were high - more than double in some cases.

Replacing all those great improved the brightness and contrast functionality and cleared up the hor. distortion.

Finally, I unmounted the focus coil from the CRT neck so the 5AXP4 would auto-focus correctly.

Next thing to fix is the power switch which is currently stuck ON.

https://live.staticflickr.com/65535/...fba88c3a_c.jpg

Bandwidth is pretty good but there is some slight horizontal waviness. Perhaps some 60Hz is leaking in.
https://live.staticflickr.com/65535/...d29b5c2d_c.jpg

https://live.staticflickr.com/65535/...d7e301d0_c.jpg

This is the focus coil I unmounted by removing three spring loaded screws.
https://live.staticflickr.com/65535/...9c6d5398_c.jpg

Sweet...

Nice!

Thanks. Here it is with the 16EP4 installed. Cool how the image appears to be emerging from the end of the cone. Quite different form the al glass CRTs I usually work with.

https://live.staticflickr.com/65535/...25e2e196_z.jpg https://live.staticflickr.com/65535/...08c88546_z.jpg

Normal vs porthole mode. Instant weight loss :D
https://live.staticflickr.com/65535/...ed0aeaaf_z.jpghttps://live.staticflickr.com/65535/...d00900a9_z.jpg

Very nice, Bob!
Hopefully you'll be able to do your magic on the damaged speaker cloth??

I know some will gag when I suggest this, but I've used a little dish soap and water, with a soft brush to clean the insides of the cabinets. just a quick job and dry it off. Never had it harm anything, and the results are amazing. Clean and fresh smelling.

Unfortunately, the fabric is torn and distressed. Short of replacing I don't there is much I can do.
https://live.staticflickr.com/65535/...1cebff8e_c.jpg

Meanwhile, I primed and painted the screen bezel with some metallic aged brass I had handy. This set had been a rental for plays and such and abused.

https://live.staticflickr.com/65535/...1d5dda2e_c.jpg

https://live.staticflickr.com/65535/...bb65b4b4_c.jpg

Fairly close to the original. Maybe bronze would be better? Either way, I'll paint the control doors to match.
https://live.staticflickr.com/65535/...b78d4f4b_c.jpg

This cloth is close:

https://www.ebay.com/itm/39231363662...ef01ab592a0aab

Thanks. Found the same pattern in a smaller size from a domestic supplier. Should be here next week.

Not entirely happy with this "aged copper" but it's better than the "aged brass"
https://live.staticflickr.com/65535/...610f976c_c.jpg

If it looks good and is proper speaker grille cloth please post the source. My porthole (and I suspect several other models) uses it and mine is just as torn up as yours.

I got it here. Diamonds run the wrong way, but it's just tall enough to rotate 90 degrees and fit.

https://www.ebay.com/itm/375306979157

Ever check auto parts stores for touch-up paint?

No, but I should. Seems like 'champaign' would be a good match. The control doors are in better condition than I thought and I will not be painting them. I'll try to bring one with me to a store and find a better match.