Garod 15TZ6 adventure
 

So, there was a monster, amazing looking combo set on FB marketplace for about two years. Periodically, someone would point it out to me, but I was put off by the size and price.
Initially, $1,000.
Then, $500.
Then, $50 and I broke down and contacted the seller. Really my intention was to just take some photos and size it up.
Even so I dragged my feet.
Here are some photos from the listing. That's a rare 15AP4 CRT in there.
https://live.staticflickr.com/65535/...8c84c6a1_b.jpg

https://live.staticflickr.com/65535/...b0678180_b.jpg

https://live.staticflickr.com/65535/...21f0f4a6_b.jpg

Then, the owner contacted me and said it was free, just please come get it.

I found out later he had check me out and realized I was a serious collector/restored and really wanted me to have it.

I guestimated from the photos that it would fit in my Honda, grabbed a bunch of tools an set out. MY thinking was I'd break it down and muscle the empty cabinet into the car.

Got cold feet on the way and called a friend that lived near the seller. So glad he was able to come over or I never could have managed it.

We broke down the chassis and removed the CRT with no trouble.
She even had amoving dolly and forearm strap that made it easy to get the huge cabinet out.
I do have the missing door pull BTW.
https://live.staticflickr.com/65535/...ffd52577_b.jpg

https://live.staticflickr.com/65535/...0ef7d332_b.jpg

https://live.staticflickr.com/65535/...66f73785_b.jpg

Doh! Were gonna need a bigger boat. Another two inches wider and we would have made it.
https://live.staticflickr.com/65535/...8cc4099d_b.jpg

My friend has a bigger SUV and he backed it over. Doh again! His hatch opening is exactly the same size!

At this point we had been the several hours, it was starting the drizzle and the owner had to leave.

I was about to give up when my friend called some guys at his workplace. Turns out their shift was ending and we were able to borrow a pickup.

https://live.staticflickr.com/65535/...f4c88975_b.jpg

https://live.staticflickr.com/65535/...0cd329c3_b.jpg

Safely at home in my garage :)
Bought my friend dinner, filled the tank on the pickup and gave him $100 cash. So figure about $200 to get it home.
https://live.staticflickr.com/65535/...876e12bd_b.jpg

Only damage was a 78 I left on the record player.
https://live.staticflickr.com/65535/...1da5df83_b.jpg

Now here's the deal. I do not have the spare for it, cool though it is. My plan is to restore it and donate to the Early Television Museum in Hilliard, Ohio. I hope to have it done in time for the next convention in early May, 2025.
That's going to be a challenge...

The rebuilt CRT appears to be dead. Possibly an open cathode I can reweld? Otherwise, I'll try to use a 16LP4 or similar.
https://live.staticflickr.com/65535/...6bc1d453_b.jpg


Some very bad things have happened to this set. I'm guessing from folks plugging it in and turning it on. It is fused, but not well enough apparently.

Caps vented, rectifiers melted and parts charred.
https://live.staticflickr.com/65535/...ca6cecf4_b.jpg

https://live.staticflickr.com/65535/...db8101b0_b.jpg

https://live.staticflickr.com/65535/...62450691_b.jpg

https://live.staticflickr.com/65535/...f2982d86_b.jpg

https://live.staticflickr.com/65535/...20891a1c_b.jpg

After reviewing the wiring and removing the crusty line bypass caps, I pulled the rectifiers and power it up. All the tubes and pilot lamps lit up :) Also, the power supply secondary voltage looked good.

https://live.staticflickr.com/65535/...5f6bc912_c.jpg

First order of business is to replaced the venter, shorted, oozing electrolytics.
https://live.staticflickr.com/65535/...13523306_c.jpg

I'm also cleaning as I go. The cadmium plating is in amazing condition under all the filth :)
Some areas have some sticky goo that comes off easily with lacquer thinner.
https://live.staticflickr.com/65535/...65ecdc32_c.jpg

Other areas have yellow corrosion (cadmium sulfide?) and I'm using CLR.
https://live.staticflickr.com/65535/...611fa864_c.jpg

They are all isolated on phenolic wafers and a perfect application for "adapt-a-caps". Little PCBS specially designed for just this purpose.
https://live.staticflickr.com/65535/...e19fd3f6_c.jpg

https://live.staticflickr.com/65535/...4d58f907_c.jpg

Glad you saved it. Stuff like this is why I have a Chevy suburban...Same hauling capacity as a long bed pickup but enclosed and heated so I can pickup 2 full size 8' wide 1960s roundy color TV stereo combos in the worst weather imaginable and get them home without any weather getting to them... It's helped me buy too much but also allows me to bring literal truck loads to swapmeets when I need to sell in volume.

Let's hear it for Suburbans. I've owned three starting in 1992. The first one was a Diesel, but that's another story.

Replacing the five power supply caps was a breeze. Each one is only a single capacitor.
https://live.staticflickr.com/65535/...68f4d379_c.jpg

Next, I dove into the separate audio amp.
The 5Y3 was traumatized and several resistors roasted underneath.
https://live.staticflickr.com/65535/...79b269a0_c.jpg

https://live.staticflickr.com/65535/...f48aefdf_c.jpg

https://live.staticflickr.com/65535/...62450691_c.jpg

The chassis cleaned up beautifully with CLR.
https://live.staticflickr.com/65535/...efc071d5_c.jpg

https://live.staticflickr.com/65535/...7a28aafe_c.jpg

I did a full recap, replaced all the resistors, 5Y3 and missing 6AT6. Also painted the transformer.
I'm happy to report it works very well. Plenty of volume with very little hum or distortion.
https://live.staticflickr.com/65535/...c2a54f62_c.jpg

https://live.staticflickr.com/65535/...4254f0a0_c.jpg

How dead is the CRT? Is there any cathode current at all?

I have found some early CRTs which appear to have an abnormally low cut off voltage. I was deceived by a tube I thought dead actually yielded an acceptable picture.

No, even at 8.4 volts. Same results with Sencore CR-70.
https://live.staticflickr.com/65535/...321408b0_z.jpg

I just have to wonder how much power it takes to MELT a 5Y3 like that, and the transformer still OK?
It must be a very large transformer, or you were just very lucky or both?
Cause the transformer in the radio part of my Hoffmen was toasted when the candohm resistor shorted out and took out the 5Y3, the insides of the transformer looked like a charcoal briquette.:tears:

The electrolytic did not measure shorted, but one of the resistors biasing a 6V6 was burned open. Several others left burn marks on the chassis above. Makes me wonder if the output stage was drawing excessive current causing the 5Y3 failure?

Anyway, it's working for now. Also, the reality is that the TV museum does not have sound on its closed-circuit signal course. Reason being they don't want people fooling with blasting sound out of the sets. So we might just leave this amp unplugged once it's on display.

It probably depends on how much the unplanned load is and how long it's ran like that. Aboa month ago I was dialing in a 27" Muntz I had fixed a month or two prior to that and it was the first time I'd seen a candohm fail in operation (let out a bunch of smoke and redplated the rectifier). Sixty five percent of the time I see a candohm it's still good and I leave it alone, 30% of the time it died decades ago and someone else replaced it and I leave it alone, and about %5 of the time it failed nobody fixed it and I end up fixing it. But I've never had a working candohm die on me before then. Luckily I caught it in time and nothing else needed to be replaced.

I splurged on some lovely Spraque Atom axial electrolytics and Ohmite power resistors for the main chassis.
https://live.staticflickr.com/65535/...caa5bf84_c.jpg

I figured I'd better focus on the charred looking area first.
https://live.staticflickr.com/65535/...b8e4c1db_c.jpg

Just as on the top, the gunk cleans off easily and the metal underneath is in excellent condition.
https://live.staticflickr.com/65535/...aa8df652_c.jpg

Not the easiest chassis to work on as some old waxy caps are buried deep.
https://live.staticflickr.com/65535/...66d7db07_c.jpg

Back topside for cleaning and tube testing. Only five tubes needed to be replaced.
https://live.staticflickr.com/65535/...056bf8de_c.jpg

Still much to do, but I figured this was enough for a full power up test.
https://live.staticflickr.com/65535/...434e30e5_c.jpg

Good news!
The radio fired right up and plays well although the dial scale is a bit off.
I was puzzled by the lack of HV though. A scope revealed no drive signal on the HOT grid.

After more time than I care to admit, I realized that when in radio mode, the TV sweep circuits are disabled.
Now a fluorescent tube glows brightly when placed near the flyback
https://live.staticflickr.com/65535/...11455f6a_c.jpg

I had to splice in a conventional anode cap as the original is the goofy snap cap Dumont used.
Woohoo! We have a raster on a little 8XP4 bench CRT!
https://live.staticflickr.com/65535/...d8532500_c.jpg

Recapping continues...

I'm tackling the vertical sweep circuit next. I expect my lack of height is due to leaky caps.
Unfortunately, there are a couple buried behind the VOT.
https://live.staticflickr.com/65535/...2a13dd38_c.jpg

I carefully unsoldered the brittle wires and unmounted it. I had to move some peaking coils to get a nut driver on the rear mounting screw.
Ah, that's better.
https://live.staticflickr.com/65535/...dbe27dbf_c.jpg

Major TV recapping is done.
https://live.staticflickr.com/65535/...a3a65538_c.jpg

I now have full raster.
https://live.staticflickr.com/65535/...fd492a75_c.jpg

Tried feeding a signal into the antenna terminals but got no reception at all.
Next, directly fed a composite signal directly into the video amp grid. That got me a nice, clear image.
https://live.staticflickr.com/65535/...27363c9e_c.jpg

Some issues on the right side. Have not tried adjusting the hor. drive yet.
https://live.staticflickr.com/65535/...c95459a9_c.jpg

First, I'll work my way through the IF with signal injection.

I really hope it's not an issue with the unusual variable capacitor tuner.
https://live.staticflickr.com/65535/...799f6794_c.jpg

https://live.staticflickr.com/65535/...6b08f1af_c.jpg

Signal injection to the rescue! Used a B&K 1077B to isolate the problem to the 3rd IF stage.
After checking resistors, coils, voltages, etc, I rechecked the tubes. The 6BA6 at this stage had 0 emissions, no filament glow and got very hot in my tester. Must have lost its vacuum. That's a shame as it was an industrial, long-life version.
This is one I had already replaced after my first round of testing.

I replaced it with a tube from my stash, but no improvement. I rechecked the replacement tube and it was bad too!
So, replaced it yet again with a NOS RCA, bingo! We have reception and sound!

https://live.staticflickr.com/65535/...b54693cf_c.jpg

I can also now see that the yoke is on wrong as the image is upside down and backwards. Wide bars should be on the left.
https://live.staticflickr.com/65535/...d7559c20_c.jpg

That means the horizontal scanning issue is actually on the flyback side, not the drive side.
https://live.staticflickr.com/65535/...d5d2be20_c.jpg

I'll work on that next.

Here's some actual video. The contrast control has very little effect and is much too harsh. It appears to work by varying the grid bias on the RF front end only.
I'm thinking it might also be an issue with DC restoration or brightness circuit.
https://live.staticflickr.com/65535/...51fa647f_c.jpg

Otherwise, it's actually working quite well. There is very good definition and i can easily make out small text in commercials.
https://live.staticflickr.com/65535/...71aaffdb_c.jpg

I missed a 100uF cap on one leg of the contrast control. After replacing that, the contrast control works as one would expect. At minimum gain, the image fades away, max gain and it's too harsh.
https://live.staticflickr.com/65535/...01f1f400_c.jpg

Swapped out the HOT and adjusted, drive, width and linearity. Better, but needs improvement. I'll hold off on that until I get a proper round CRT with the right deflection angle.
https://live.staticflickr.com/65535/...8efe16fe_c.jpg

https://live.staticflickr.com/65535/...aefdb232_c.jpg

Wow that was a nice score for free. It reminds me so much of a Dumont. Excellent work Bob

Thanks. Maybe a passing resemblance, but it's quite a different design than a Dumont.

I dug up a used 16DP4 CRT to try out tonight.
https://live.staticflickr.com/65535/...44eb676e_c.jpg

First without a focus coil just to see if I could get something.
https://live.staticflickr.com/65535/...c1a3ba54_c.jpg

Promising, so I slid the focus coil on the neck and spent a little time adjusting it, the ion trap magnet and yoke.
Better.
https://live.staticflickr.com/65535/...4bde8149_c.jpg

Yes, this will work. Hoping to use a similar 16LP4 which has the right deflection angle eventually.
https://live.staticflickr.com/65535/...65ec2fb8_c.jpg

https://live.staticflickr.com/65535/...24a3f846_c.jpg

Bob, I have to say that it doesn't get much better than that! Good on 'ya.

Pulled the record player out of the cabinet and gave it a closer look.
It's absolutely filthy just like the other chassis.
https://live.staticflickr.com/65535/...53e124e9_c.jpg

It's a Webster model 256-2 than plays both 78 and 33 rpm.
Curious that there is a relatively modern blue plastic crimp connector.
https://live.staticflickr.com/65535/...8273c0fa_c.jpg

It's actually bronze color under that filth.
https://live.staticflickr.com/65535/...1769e559_c.jpg

Those changers revive fairly easy. The one in my Dumont manchu just needed the idlers, capstan and inner platter lip cleaned with Goof Off, a new pickup cart and some oiling.

Ah, that's better. Motor is good, idler wheels and motor mounts need replacing.
https://live.staticflickr.com/65535/...a665a7e3_c.jpg

https://live.staticflickr.com/65535/...dd894f93_c.jpg

A friend with far more experience than I with record players stopped by today. It took most of the day, but in the end he did get it playing!
* Motor mounts have been replaced
* Changer mechanism lubed and working
* Crystal cartridge replaced with a modern ceramic one.
* Idler wheel has a dent but grips OK - I will look into replacing it
https://live.staticflickr.com/65535/...8f06fe3f_c.jpg

While he was working on that, I took another whack at the 15AP4 CRT.
I went through all the various restore/rejuv modes in the CR70 "beam builder" with no results.
I was about to give up when I gave the Manual restore 2 mode (the most aggressive) one last try.
This time I finally got a flash in the gun!
Emissions finally appeared but weak. Also the grid shorts test is borderline.
https://live.staticflickr.com/65535/...2f4035fb_c.jpg

If I crank the filament juice from 6.3 to 8 volts, the emissions are also borderline.
https://live.staticflickr.com/65535/...bd4d1d42_c.jpg

So, let's give it a try.
https://live.staticflickr.com/65535/...564331ac_c.jpg

Eventually I found the ion trap magnet sweet spot and got an image.
Brightness and contrast have to be set low on the image goes all weird. Sort of washed out and inverted.
https://live.staticflickr.com/65535/...1982b26a_c.jpg

I installed a brighteener and it improved a bit.
Other issues continue to crop up though. Keep in mind the image should fill the entire screen as this is a porthole set.
It is also sporatic. We had a decent image that just about filled the screen. Turned the set off and back on and now it's like this.
Stretched on left and compressed on the right.
I'll go back to the small test CRT while I troubleshoot the sweep circuits.
https://live.staticflickr.com/65535/...1c88d191_c.jpg

That is one of the basic/common symptoms that identifies a weak CRT, but you probably already know that very well. I think you "did your best", now hold it for the day when you can get it rebuilt. It is certainly worth it.

The record changer looks great!

Thanks. I plan to poke around with the rebuilding equipment at the ETF in the spring. At least to get more familiar with the steps involved. Who knows - I just may attempt to rebuild it myself someday.

Bob, I never knew Mr. Chekov on Trek was so "jacked" HaHa. As to "playing around" with the rebuild equipment, I think I probably speak for some others... I'd love to observe that process. It could be an interesting event for the museum. My old mentor back in the 80s told me he had the chance to observe a rebuild facility. It's something I've always wanted to observe.

DON'T make fun of Bester like that, he's a P-12 and can rip your mind apart!:D

Wish I had realized sooner the chassis sides come off!
There are still parts behind the VOT and along the back that are hard to get at, but it helps.
https://live.staticflickr.com/65535/...606e79d4_c.jpg

Here's a better look at the crazy tuner.
https://live.staticflickr.com/65535/...a418cb64_c.jpg

Some of us watching from the sidelines were wondering why you were doing that the hard way. Oh well it increases the entertainment value. :D

It doesn't help much though since pretty much all the paper caps and electrolytics are in the middle and along the back. Even with the side off, you still can't get at the cap behind the vertical output transformer.

Nice to have easy access to the tuner and IF, but I REALLY hope I don't need to touch that stuff.

Cleaning the relay contacts eliminated the instabilities when switching zoom modes. Swapping out the 5V4 help considerably with the horizonal linearity. Still not great but better.

Back to a rectangular 8XP4 test CRT for now.
https://live.staticflickr.com/65535/...1ee36ea8_c.jpg

Expand mode.
https://live.staticflickr.com/65535/...68c50953_c.jpg

Normal mode.
https://live.staticflickr.com/65535/...d2c04029_c.jpg

https://live.staticflickr.com/65535/...5d148b56_c.jpg

I've had two sets with horizontal linearity problems that were corrected by changing the output tube to the correct type.

Winter is finally over and I am able to do some workout side on the cabinet.
https://live.staticflickr.com/65535/...71528a5b_c.jpg

Mainly, I need to do some repairs and refinish the bottom skirt. The set got wet at some point in its life and damaged the finish and the glue is failing.

https://live.staticflickr.com/65535/...3131d1e7_c.jpg

This area is the worst. It's also delaminated and warped on the inside compartment for record storage.
https://live.staticflickr.com/65535/...86054c8c_c.jpg

I decided to just remove the loose boards so I can work on them indoors. I also means if I leave them off, it will fit in my vehicle.
I can reattached at the convention in Ohio in six weeks.
They have me scheduled to reassemble and make final adjustments Friday afternoon as a demonstration.

A little heat helped loosen up what remained of the glue and all the boards came off easily.
https://live.staticflickr.com/65535/...2943b56a_c.jpg

Legs have been stripped. Next up sealer, grain filler and toner lacquer.
https://live.staticflickr.com/65535/...319900c0_c.jpg

Taking advantage of a nice day to do some grain filling.
https://live.staticflickr.com/65535/...b2a1b718_c.jpg

Scraping off the excess. Messy and tedious, but crucial to get a smooth "piano" finish like the rest of the cabinet has.
Next up, toner lacquer.
https://live.staticflickr.com/65535/...ecd97a50_c.jpg