Admiral 30A12 restoration
 

This 10" B&W Admiral set from 1948 just showed up on my door step a few days ago and I thought I'd poke around with it while I wait for lacquer to cure on my GE cabinet.

it was generously donated by an online friend along with some test equipment a GE radio and a whole box of Sams (radio only).
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It's dirty, missing the back, channel knob is wrong and the cabinet is a little rough, but otherwise it's all there.
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Luckily, I have a spare channel knob handy and the screen area cleaned up surprisingly well with a little Howars RAF, steel wool and Windex :)
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Some of you may have noticed it's the same set as my avatar. True, but this has the original finish while my other set does not. When I received it, it had been stripped down and clear coated with polyurethane. I stripped all that gunk off and refinished it with toner lacquer. I had a hard time finding good photos of this set and guessed a little about the proper color.
I can clearly see now I didn't get it quite right :o
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Anyway, continuing on with this set, the CRT tests very good :) I also discovered almost every tube appears to be the original Admiral and I see little sign of repairs.
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Filthy for sure, but not much rust. The fly looks OK and it's fused.
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I now have five of these 30A1 series Admiral sets but have never actually seen one work as none of mine have been restored yet.
So I decided to try a slow, control power up. First I pull the rectifiers out, powered it up and all the filaments lit up :)


Next, I reinstalled the rectifiers, put a 150W bulb in series and slowly powered it up with a variac. Around 100 VAC I heard a hum out of the speaker.
I took the bulb out and increase to 115 VAC and thought I hard a little HV crackle but no glow in the CRT face. A little tweak of the fine tuning got me nice, loud clear sound :music:
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A little tweak of the ion trap magnet got me a very bright, crisp raster :thmbsp:
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It's trying hard to lock, but can't quite make it. I went around to the back and adjust the horizontal oscillator and finally, got a lock.
I then had to crank the height up all the way to get this image.

Oddly, I could get channels 2 and 6 to work, but not 3, 4 or 5. I hope it's just dirty contacts.

Not bad for 65 year old parts :yes:
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Now I did smell all sorts of aromas emanating from the set - burning dust, ozone, hot wax and cooked resistor. So I ceased my testing,

A little later I pulled the chassis for a closer look.
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One casualty found so far.
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After a little cleaning, it's starting to look more respectable.
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A low-hours set and a half-watt resistor is all you need to worry about frying, then you have a rare set that will get sound and picture.
I would not try it with any of my RCAs, and probably not a Philco or Sylvania either.
Only Admirals & Zeniths seem to be able to come to life with that minor intervention.

I started testing a few tubes and a few are weak have secondary emission or both. I think only three tubes are not Admiral branded - 5U4, 1B3 and 6Y6 audio output.
Now I don't expect to keep running this set on all those original caps. I just find it interesting to slowly replace parts methodically for a change rather than shotgun them all.

They MUST have made a blue zillion of these, & the 7" sets..The story on MY 1911A1 7" Bakelite set was that the guy who owned the theatre in town got it, He & his pals would take it up on Dump Hill, the highest place in town, & could SOMETIMES pick up WSB or WAGA out of Atlanta..We didn't have TV around here til late 1953 or '54..

I don't know about these 30A12 sets. It's one of the first models they sold and I don't see many around.
The other versions with the "X" on the speaker grille like this seem to be a lot more common.
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I replaced the fried resistor, cleaned the tuner, replaced a weak 6SN7 vertical oscillator tube and made a crude repair to the broken fuse holder.

These old Admiral sets used and odd fuse size. It's the same diameter as modern fuses but they were shorter.
Someone jammed a full sized fuse in there and broke the mounting. I'd like to find a source of these shorter fuses, but I don't think they are made anymore.
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This crumbling power resistor still tests OK, but I plan on replacing it.
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Those tweaks definitely helped. I now get clear reception through channel 3 and better vertical height.
I just realized the image is much too wide though. This set has a rectangular mask and a lot of this image will get cut off.
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Nice find and not bad performance for a 65 year old set running on old parts. The chassis looks similar to the one that's in my '49 combo; which, I need to get going.

Fuse
 

Hi Bob
What is the physical size and what current rating of the fuse?
Joe

250mA - 1" long 1/4" in diameter. I believe that's an 8AG type and Digi-key has them. $1.72 each - ouch.

I pulled and tested all the tubes. Almost all are Admiral. The rest are Sylvania. All test very good and nearly the same. That seems to confirm my hunch it's a low hours set.
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Nice when that happens. I wonder if the 6J6 has a different origination due to the hex around the tube numbers.

The one on the left may have faded and yellowed, like many other old cabinets. I would look in the back or the inside for a finished area that wasn't exposed to light. That would give you a better idea what its original color was. Edges of that nature may be exposed when you remove safety glass bezels or speaker boards, for instance.

Phil Nelson

Thanks for the tip. I started measuring the old paper caps and wasn't too surprised that every single one is leaky to varying degrees. The resistors aren't too bad and the electrolytics seem to have some life left.

Originally, I figured I'd restore this set a section at a time and see steady improvement. The reality though is that the longer I run it on those old parts the more problems pop up. Lost sound, lost vertical sync & height, etc.

Even one of the tubes that tested great developed shorts. Also, I tested about a dozen paper and electrolytic caps and all are leaky to varying degrees.

So, I think I'll stick with my usual approach of shotgunning all the caps right away.
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Recapped power supply/amp chassis.
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I'm about 75% done with the main chassis too.
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Sync is pretty solid now but the sound is weak and the picture isn't as bright as I'd expect.
Also, the picture is too wide considering this set has a rectangular rather than "double D" mask.
Perhaps both those issues are related to low HV so I decide to poke around in the HV cage. Very easy to do on these sets. Just remove three screws and the side comes off.
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There I discovered the 1M resistor inline with the second anode as about 70% high!
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Fuse
 

Hi Bob
Send a address and I will send you a box of five fuses. 1/4 amp one inch long 1/4 inch dia.
Joe

Thanks, I'll take you up on that offer :)
This set has become rather frustrating. Especially since it was working fairly well on mostly original components. Now that it's been fully recapped, I still have some nagging issues remaining.

1. Excessive width. I need to reduce the width by about 30% so something has to be way off. I've replaced all the caps and checked/replaced all resistors. Also swapped the 6BG6 HOT and adjusted the drive and width controls. All that had minimal effect. Time to check the few mica caps I guess.

2. The tuner has some nasty issues. When adjusting the fine tuning the picture cuts out. I have to tweak the channel knob to get a clean picture. I have cleaned the contacts but I think it's time to pull it out for a closer inspection.

3. I don't get any picture until the brightness is about 3/4 clockwise. The CRT tests very good but the cutoff test stinks. Perhaps I need to alter the grid bias ?

4. Sound stinks. Hopefully it's just an alignment issue.

Oh well, if it was easy it wouldn't be much of a challenge now would it ;)

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I see a selenium rectifier just to the right of the power switch in your above picture. Those are known to go bad. What does it do in your set?

Good eye. It's tied to the 6.3 VAC filament supply and I believe it creates a small negative bias for a few tubes. It's definitely on my list of many things to check :yes:

I was just looking through all the caps I clipped out of this set and was surprised that about half are Dumont branded. Most of the rest are Cornel Dubilier with a few Sprague and Micamold in the mix.

I've spent far more time on this set than I ever expected trying to track down the excessive width issue.
Finally, as I was about to abandon all hope, I noticed the huge power resistor in the HV cage was cold! An ohmmter confirmed that it was open.
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Now where to find a replacement ? Luckily, I have an entire space 30A1 parts chassis but it too was bad.
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So, I pulled one from another of my Admiral sets,. Ugh! All three are bad :tears: I'm guessing this was either a common point of failure back in the bad or they go bad just sitting idle over the years.

I have a coupe more sets to scavenge from otherwise I'll cobble something together.
Regardless, I'm going to have to find a source of replacement 5,300-6,300 ohm 50W resistors if I want to get all my sets working properly.
Note the taps are 500 ohms apart and used to correct horizontal linearity if needed. All my sets use the center tap so that would be 5,800 ohms.
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Hi All;
Bob, It looks like it is the same as what is used by RCA in the 630, and 830 type of sets.. Possibly more, or other RCA early TV's.. The Flyback also looks like it could be the same..
THANK YOU Marty

I pulled one from every Admiral set and chassis I have and they are all bad :dammit:

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Yes, it both looks the same and is the same value. So I suppose I could borrow a good one from my 630TS.

This was Admiral's first TV on the market so I bet they were cautious and cloned RCA's HV design.

If the open is between the 2nd and 3rd terminal (counting from the bottom) and if the ohms between the 2nd and 3rd, and the 3rd and 4th terminal are supposed to be 500 ohms, connect terminals 2 and 3 together (to bridge the open) and connect the wire that was on the 3rd terminal to the 4th (top) terminal.

Great idea, but unfortunately it's the main element that's burned out in all seven :(

I dug up a 7500 and put 20K in parallel to get about 5500. I'll replace it as soon as I track down something more suitable.
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Yep, that did the trick :yes:
Now I'm curious. If I had realized it was bad right away and replaced it without doing the full recap, how well would the set have worked :scratch2:
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Well Bob, how about going to Mouser or one of the other vendors and just getting a few of the values that work and just putting a single one in? (If I understand correctly, the taps are for selection to get the right width?)

Possibly, you could find a hollow power resistor and just mount it in the same place, or alternatively, just use resistors similar to the ones you are trying temporarily.

I have to thank you for your tenacity. You find and attack all of the "Tough Dog" problems and come up with solutions so that when we get going on a project, you have already found and fixed it!

Oh yeah, it looks great!!!

Hi All;
Bob, Congratulations on getting the Admiral going.. I find that interesting, in that even if it is mostly the same design, the Bad section in the one in my 8T30 is the one between the second and the third lugs (500 Ohms) and not the first section of 5800 Ohms.. Is is the First section that is bad in all of your resistors that you have checked ??
THANK YOU Marty

According to the service info, you use he center tap unless you can't get hor. linearity by adjusting the linearity and drive controls. However, it clearly does affect the width too.

The only 50W fixed tubular resistors available are 5K, 7.5K or 10K. Coincidentally, the 7.5K are on sale at Allied so I ordered a few along with some 20K power resistor to put in parallel. There are also adjustable 50W 10K resistors, but the power rating is proportional to the tap position. So if I put it around 6K, I've reduced it to a 30W resistor.



The first section is bad in every resistor I checked :(

I forgot to mention that I've already shocked myself on the twisted leads of the 10K power resistors sticking outside the cage while reaching for the drive control. :yikes:
I now have a nice little burn mark on the side of my thumb.
It's been quite a while since I shocked myself and I think I was overdue.

Years ago, when our beloved sets were just old, the horizontal output tube cap in a CTC19 I was trying to fix nailed me. I seem to remember seeing a black line running up my arm afterwards...

Are you sure it wasn't brown and on a different appendage? :thmbsp:

Ohmite makes 25W @ 2k, 2.5k, 3k, 3.5k, 4k - bolt a couple end-to-end and you'll be in the ballpark. Wattage divides between the two, and I bet the original 50 watt rating was plenty conservative. http://www.mouser.com/ds/2/303/res_270-231448.pdf

Good idea and I did consider it, but they are about $5.50 each or $11 per set.
Instead, I went with some 7.5K 50W Ohmite from Allied on sale for only $4.68 :) I'll add a 20K 10W resistor in parallel to reduce the value.

Since I need six of these the price difference really adds up.

P.S. I agree about the power rating because it really doesn't really get all that hot.

The new resistors have arrived. It turns out the modern 50W Ohmite resistors are about 1/2" shorter and smaller in diameter than the old ones. Still, they should fit fine.
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I also popped out the tuner and gave it a good cleaning and lube. It's operating much more smoothly now :)
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I reinstalled the tuner, installed the new power resistors, replaced the electrolytics and cleaned up the chassis a little. I'll try powering it back up in a few.
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The picture is good and the sound is getting better, but still weak. Also, the reception on channel 4 is terrible, but pretty good on 3 :scratch2:

I really hope to get this sorted out over the weekend :yes:

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No doubt in my mind...

I tried doing an alignment and discovered a broken slug in the IF can on the tuner. I suspect it broke when someone tried to adjust it because it's an odd design in that it performs two functions. The top slug is for video and the bottom for audio. You need to use a very slender alignment tool passed through a hole in the top slug to adjust the bottom.
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It's L106 on the schematic. I think every other split carrier set I've encountered has the audio trap on the main chassis and the tuner has a single output. Admiral made this change in later models too.
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Luckily, I had a spare tuner and popped it in and proceeded with the alignment. That solved my problem of lousy reception on channel 4, but the sound was still bad.
So I proceeded with the alignment and ran into another problem. Some of the IF coils don't peak. In fact adjusting the slugs seems to have no effect at all.

I decided to pop out the first audio IF can (T201) for a peek inside. Sure enough, it has the type of exposed mica cap that so often go bad in radios.
I carefully disconnected one end of the coil in parallel to the the cap. I measured no capacitance and it's very leaky on even the lowest voltage range!
Unfortunately, I don't have any 30pF micas on hand so I'll have to order some. Might as well get some for the other IF cans as well.
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I replaced the bad mica cap in the audio IF can and that did seemed to do trick :)
Then, I moved on to the video alignment and discovered that none of the three traps would peak. So I popped one open and discovered another bad exposed mica cap. I'm sure there's a bad mica in the other two IF cans too.

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