Speaking of RCA factory stunts........
 

Does anybody remember the RCA Victor tv I'm working on? The 6T74?
Original chassis. KCS 47A., oorrr, -1. whichever.
The vertical oscilator is a 6SN7, that doubles as a Sync amplifier.
Has a better video amp circuit, as well.
Well, here's a new one.

Someone recently sent me most of the gutts to the same model set, 6T74 that belonged in his family. He's turning his cabinet into a licquer cabinet. Ugghh....
Well, guess what?
This was his original chassis, and, the tube chart in the case shows that, but, it's different.
It is the cheaper chassis that used the 6J5 for vertical oscilator.
what goes on here?
The serial no , and, the painted picture tube cup point to a later production.
Did RCA get cheap????

Progress note. I believe I nearly have the problems licked on my set.
Bill Cahill

Glad to hear that you are reaching breakthrough! :thmbsp:

As for getting cheap, RCA in some of their models was a leader; they went downhill from 4 or 5 pix IF stages in the late '40s to a minimal 2 in some of their mid '50s B&W sets. I've even seen this pitiful minimum pix IF count in some of their COLOR sets in the mid '60s.

Further to mention here that very few of their FM Hi-Fi sets used the Foster Seeley discriminator, but rather the ratio detector design, which has always proved inferior in performance as regards distortion figures, etc....

I've restored in the past a number of sets that employ the cheap 2-stage pix IF chain--including RCA models, but was never really satisfied with their performance. I suppose that if I at the time was a trained TV technician that I might've done better, but I strongly doubt it. I think that they were generally crummy sets meant for urban use only, and I never had lived in an urban area.

Now I've got a question for you: Have you ever seen any model of Zenith television set with any fewer than 3 pix IF stages....?

Actually, yes. Early SS Zeniths some had 2 if's.
The chassis's I'm talking about in RCA still had 4 vid. I F's.
Bill Cahill

So where did the sync amp go? Is there another triode added somewhere? I'm missing something here....:scratch2:

That's my point. On the cheaper sets, thiere is a sync seperator, and, one sync amp. On the better chassis, there are two sync amps.
On the better chassis, also, the video amp has improvements over the other one.
All the way around, supposedly, the looks of the more expensive chassis was supposed to look neater. On many of the cheaper sets, for some reason, they copper plated the tuner, and, often, the brackets for the front controls, but, left the zync plating off.
They also obviously didn't examine every construction job, either...
Bill Cahill

My RCA is back up on the bench while moses' rp is awaiting parts.
I will be trying the set soon.
Just looking it over.
Hope to try it Sunday, but, definately Monday.
Wish me good luck, guys..
Bill Cahill

Bill,

You gotta go to bed! This business of being up at 4AM ain't gonna get that RCA done! You will b

Just pulln' your chain. I tried to call you today, you didn't answer...;)

I was at grocery store today. I'm home now.
Bill Cahill

Maybe I'm misinterpreting things, but that you're doing 3-4AM grocery runs means you must live somewhere that a Muntz TV might actually work. :D

Huh?? My grocery run was this afternoon. Muntz? I haven't worked on it yet.
Bill Cahill

The post you made saying the RCa was back on the bench has this for a timestamp:

03-01-2009, 04:41 AM

I can't explain that snafu.

I found out that the first vid. I F transformer, which was physically dammaged, but, at one time worked, now was open.
I ended up getting a friend to ship me one out of a junker KCS-47.
I finnished installing that yesterday, and, plan on trying set, again, today.
On last try, I had hv, vert., and, raster.
Hope this will now bring set back to life.
I'll post pics when I know more.
Bill Cahill

Well, some good news. I had tried set, and, no play. I had a raster, no sound.
Today, I found an open B+ resistor to I F stages, then, the reason. A tiny beed of solder shorting B+ terminal on Second video I F to chassis.
Solder gone... Now, I'll replace resistor.
I have a feeling that now it will work.
Bill Cahill :thmbsp:

Ladies, and, gentlemen, may we have a drum roll please?? ........... Thank you.....

I have an important announcement of great joy to make!!!!!
Picture speaks louder than words......

http://i18.photobucket.com/albums/b1...RCAplaying.jpg


I still have adjustments, and, tuning to do, and, am on my way on that.
But, after the last two long, hard years, It's finally playing!!!!!!
I've had it up to line voltage several times for several min. each, so far, and, it keeps a playing...... :banana::D:tresbon:
Bill Cahill

Ya made lemonade from the lemon!

It has no choice but to work now.

Congrats!!:banana: