I had posted awhile back asking what kind of Admiral my Dad had as his first tv:

http://www.videokarma.org/showthread.php?t=246594

Bgadow said he had a similar one in kinda rough shape. I had been meaning to head down his way and meet him, so I made a road trip. I brought it home, and in spite of a bad finish, it was otherwise complete, only missing its masonite back:
167445

167446

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I am nearly done refinishing the cabinet now, but I am still stumped on the same issue Bgadow was having with the thing. When the set's contrast is turned down, you lose all video, leaving a blank raster. When you turn up the contrast all the way, the picture returns and overloads. You get a poor but stable picture for maybe an 8th of a twist of the contrast knob (on this set, the contrast is part of the antenna circuit). All voltages check out fine, all tuner and IF tubes have been subbed out. The set has been recapped. I can run the set just fine inputing video straight to the video amp, but I'd like to know what is happening here-I'm sure Bgadow would like to know, too.

I've been using the Rider's available on the ETF (30A14), if anyone wants to follow along:

http://www.earlytelevision.org/tv_schematic_diagrams.html

I'm working along to get this thing ready for Father's Day (looks like I'll be seeing Dad on Monday). I'm still more focused on the cabinet causing delays more than anything else. I only have to put the top clearcoat of lacquer on now...

I'm probably being dumb here but check C301 to make sure it was installed with the correct polarity. Plus goes to ground.

John

Good idea John. Also checkout the production changes for the contrast on page 5. They changed C301 from 4uF to 50uF as well as some other parts.

I'm not sure on this set but on a lot of 40's sets it was normal to adjust the contrast by adjusting the gain, so it sounds like yours is doing what it's supposed to only too much so?

Have you checked the contrast pot for continuity all the way through it's range? a bad spot on the carbon might cause this.

C301 was installed with reverse polarity according to the schematic-but this didn't sit too well with me. I have looked at a number of chassis pictures from this and similar sets, and they all appear to be installed in this manner. No matter, it didn't change the issue anyway.

This is a later run chassis from what I can tell, and the 4uf has been stepped up to 50mf. I'll confirm the rest to be sure.

I would normally associate this sort of thing with a fowled up AGC adjustment, but I don't think this set has an AGC pot. I'll keep digging into this schematic to see what there is to see...

I'm new at this site. As I don't quite catch how to set up and post a thread, I'm responding to a close thread. I'm searching for the channel selector and fine tuning knobs for my Admiral 22X27, a 12 in. screen. Also, if possible, I'd like the control panel also. Thank you-- George

This chassis does not have AGC, as many early sets didn't.

Therefore, the contrast control is the gain control for the tuner's RF amp, as well as the picture IF strip. It is acting correctly as you described.

The correct procedure for tuning a picture on a set with no AGC is as follows:

Allow set to warm up. Turn contrast and brightness all the way down.

Select the channel you wish to view (or feed your digibox on in this case.)

Advance the brightness control until a raster is barely visible.

Advance the contrast control until a normal picture appears with no signs of bending or pulling. Adjust fine tuning for best sound.

You may find it necessary to readjust the fine tuning for best sound after a period of operation.

The above procedure was pulled right from the owner's manual for an early Admiral set.

I hope this helps.

Thank you very much for that quote from the manual. I have the chassis all apart right now, but all of my measurements just tell me the set is working normally. When I get it all back together I'll follow the steps as you describe them.

The cabinet got its last coat of lacquer today, and it looks great! Several of my neighbors saw me finishing this thing up, and they all said it looked great. I guess they had been watching me pounding away at that ratty cabinet every night for the last week.

edit/update:I just put it all back together, and it is a LOT less touchier than it was. I cleaned all of the tuner parts while it was apart, as well as the tube pins, etc. Following a post of Banderson's on adjusting a trimmer for optimum sound, I was really able to dial it all in! I think I'll put it all back together tomorrow and give the set a shakedown test.

Awesome :banana: I can't wait to see it playing.

Awesome :banana: I can't wait to see it playing.

+1 for me, too....

I've been watching it all weekend, with no real issues. After about 15 minutes, the horizontal hold needs a quick tweek, as the picture will bump over a bit so you can see the blanking bar. If this were my set, I'd live with it, but since I need it to run its very best, I'm going on a resistor hunt tonight.

How did it turn out ?

It was delivered on Father's Day, and it is still running strong! Dad was very excited to see it come up the stairs, and while he knew that I played with old radios and tvs, he had no idea that it would be possible to find as set so old.

It doesn't have an decals on the cabinet, so getting some repros made up will be one of those "someday" projects. I would have taken pictures, but the little lady had borrowed the camera and wasn't able to find it.