now with sound!
https://youtu.be/KxRb9aPu8Cs
will look a bit better once I can set contrast and brightness correctly! :)

I just ordered a handful of pots, to try and recreate the controls for this thing, MOST are all of the same type, except for the brightness cont, which I got a one of a bigger power rating, cause it has 120bias to gnd across it, i don't want any burn outs, all the rest have minor voltage on them.

I could not find a 600 ohm for contrast, using a 500, don't think it will matter that much.

this TV did not have a tone control, don't see the need to add one, even though I could.

control assy made

https://i.imgur.com/SDqrxZ3.jpg
https://i.imgur.com/7O46OW1.jpg
https://i.imgur.com/qGPQzDA.jpg

it all works!

Progress update...

Over the weekend, I did manage to get something tuned in through the IF section using a Castle TV Tuner Subber, however there was a noticeable 60hz noise in the video, so strong that it was interfering vert lock, I'm not sure if this was a grounding issue or due to bad caps in the subber, I did only pay $9 for it after all, I could try to stick batteries in the thing and not have it on AC, and see if the noise is gone, but the point was to see if the front end worked and it seems it does somewhat.

Now the choice is, find an alien tube VHS tuner someplace, hook it up make it work, or stick with A/V input...

I'm still trying to decide what to do with this thing, point #1, 24AHP4 is weak but not dead, and still gives a decent picture, surprisingly, but there is no telling how long it will last, with limited use, could be months or even longer, a year or more, no way to know.
Once I have the chassis all patched, I intend to build SOME KIND of wood cabinet to fit all it in even knowing the tube may fail some day, even if it does, ETF has several compatible 23 inch tubes that I can fall back on in the event the 24AHP4 does croak.

I already have a rough idea what the final project will look like, which comes to the other thing that I'm on the fence about, tuner or no tuner, since I have already established that IF is working, RF input is an option, however, the tuners to be found on eBay are just tuners only, where as they can probably be made to work, and adjusted to ACG and all that, they come with no knobs/ dials/ channel indicators, all that would have to be found, granted, once tuned, they will almost never be set again, or almost never, but finding the right ones that fit/ work and are aesthetically pleasing will be tricky, vs just going with direct A/V input.

:o

Been thinking about this for a while now, and this is most likely what I will do, the 24AHP4 works fairly OK, after it has been on a few min, but could do with a slight boost, very slight.
The specs say it can work off of DC as well as AC, right now, its hooked to the 6.3v windings with all the other tubes.
I'm going to make a rectifier / regulator circuit using a LM317 and bridge rectifier, due to the AC-> DC conversion and filtration, I should be getting more than 6.3v DC out of the bridge, how much, no way to know till I build it, then I just set the LM317 to what ever final boosted output level I want.

Picture sure looks nice for a set with a weak tube.
Good job bringing it back to life.

A few observations. If you are going to source a raw tuner and separate knobs for it then you want a tuner that uses removable interchangeable channel strips, but NOT a wafer switch style tuner. Different knobs for different tuners number the knob and key the shaft different from tuner to tuner. Interchangeable channel strips allow you to change where each channel is relative to knob rotation so you can swap strips and make the channels match the knob.

LM317s IIRC can have a minimum regulation drop 1.35V...so for example if your rectifier outputs 7V you can only get 0-5.65V out of it and have regulation.

You could use a voltage doubler rectification circuit to get around 12V and circumvent that min voltage drop of the LM317.

Both the tuners on eBay are the strip type, so if I do get one, that is most likely what I will do.

problem is always with a voltage doubler is stable current with unknown current loads , granted, the regulator could stabilize it.

i played with it some more on a variac , I found that bringing up the input voltage from 120(ish) to 129 raised the heater voltage to 7.1 volts and made a VERY noticeable improvement on the screen.

so i did a bit of digging and found a 12 volt 3 amp DC power brick.
so I will take that, a LM317T,a 5W 8.7V Zener Diode as a crowbar, and a 1 amp mini fuse.
and set it to 7 volts or so, I should never reach the 8.7 threshold, so the Zener Diode should never clamp and blow the fuse,

Brightener circuit done.

https://i.imgur.com/IHTbXYq.jpg

source is a 12 volt 3 amp DC PWS, set to 7.2 ( aprox ) have a hefty 8.5 ZD clamp on the output to protect from overload, and 100mf filtercaps, I don't foresee ever going above 8v with this, and if I do I will just replace the ZD.

https://i.imgur.com/39W7mv1.jpg

I will most likely will try going with a tuner, the input to the video output is 1.5 or so, and composite is 1.1 or so, so the contrast is a WEE bit low for direct video input, but not very much, abut there is also no agc, so the best way would be to try a tuner, i guess.

https://www.youtube.com/watch?v=pbTrs9OdTFQ

latest video test.

pretty much at the point to build something to put it into now.

Meanwhile, while I'm working out how and what to build to put the guts of this “Big Mama Magnavox” into, looking around locally I found a mystery Admiral television, looks to be in poor shape, and so far, the only info I have is the pictures of it, no date or MO#.

Anyone seen this Admiral before? :o

https://i.imgur.com/aqhzyyJ.jpg
https://i.imgur.com/nqWsJAM.jpg

I have seen them at our local radio club auction. That is typical early 50s Admiral styling, with the chassis on its side. Very easy to get going usually with plenty of room under the chassis and no crazy parts. Similar to the 26R12 Admiral that I have.

The Admiral is a 1952-53 model by the looks of it. Looks pretty nice if it's local and the price is reasonable. I'd want to test the CRT in it first if I was going to spend any significant amount of money for it.

A slightly earlier model used a 16” metal cone round tube...

http://www.tvhistory.tv/1950-Admiral-26X56A-16in.jpg

My guess is that the set in question has a first generation rectangular CRT, like a 20CP4 instead of a later, more common 21inch tube. Might be difficult to find a replacement. :scratch2:

jr

Or, it may just be a 17 inch CRT which is from about that era.

A likely possibility! Sams 135-2, which covers a bunch of early 50s Admirals shows both 17” and 20” tubes in use.

http://www.earlytelevision.org/pdf/a...sams_135-2.pdf

A 17BP4 should be easier to find than a 20” jug.

jr

Unfortunately, someone got it before I could. :tears:

Thanks for the info though. :)

decided to add a retro mod to my project! :)

https://www.youtube.com/watch?v=GC8MnvbTrts

Since I lost the chance to get the zenith television, I have decided to pull this project out of the shed and try to toss it together again.

It does work even though the CRT is weak and lacks contrast, but does get a bit better as it has been on a while.
It uses a 6EB8 for the video output / sync sep, looking on the sub chart, it;s said that a 6JT8 is a drop in compatible replacement, and on an audio site I saw... " Plenty of cheap tubes to choose from in that footprint, though - 6GN8, 6HF8, 6AW8 and more. 6LY8 and 6JT8 have more gain in the pentode section,"

And more gain in the pentode section may be just what this tired old CRT needs to limp along for a few more years of light use! :D

Feeding the CRT with strong signal will definitely helps and is worth but, if the signal surpasses the k-g1 bias (eg. a CRT with 60V cutoff and a 70Vpp signal) will make grid current, and the result is annoying bars at the side of contrasted objects like captions or subtitles, for example. Good to carefully adjusts the contrast.

https://www.youtube.com/watch?v=PvMHr4-WO8s

New video with the new tube 6JT8, It did make a difference! :yes::D

nice

I saw this topic just today. I am currently working with a Magnavox Stereo Theater with this same chassis. I'm thinking it is a version of the C36 chassis. They made several different versions of the same chassis. The ones for Stereo Theaters used the 6GC5 audio output tube for a cathode follower, then fed the audio thru the stereo amplifier. My set has the 27ZP4 picture tube, which tested much like this one did, but at least it lights and I have a full raster. The problem I'm currently having is that I have no audio nor video, so I need to try to troubleshoot that. Sams has schematics for the C36 series chassis, but none of them are exact. I hope I can get mine going since I have had the rest of this thing apart as far as I can get it, including the cabinet. I found it in an abandoned house in Detroit that was being torn down. It had a half inch of cigarette scum all over it. Mine has remote control and the whole shot. Top of the line model for 1962. Mine does not have the UHF option.

From what I can see, the ones set up for audio output via a separate Stereo amp , tap off sound at the plate of V7 before the 6GC5 audio output tube, but still have the 6GC5 in there as a voltage divider for the 120v source, which is critical for the video and audio IF sections, and the tuner, so if there was no 120v, you would have raster only

I have a Tolex project on the bench at the moment, and as soon as it is done, I need to get back on this set. It's been awhile since I worked on it, so I need to replace the AGC resistor which has drifted low, then power up and see what I have. I have a set of test/extension sockets, since the tubes in the IF strip are in non-removable shields. I'll do some voltage checks and go from there. My problem is likely from the If strip to the tuner someplace. I hope the tuner doesn't have to come out. What a bear....