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  #16  
Old 09-14-2017, 02:04 AM
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Quote:
Originally Posted by SpaceAge View Post
Ya might be able to 3D print that door. It is 2017 after all.
My thoughts exactly!

Quote:
Originally Posted by mrjukebox160 View Post
How long did you leave the CRT on? It might wake up and if not it might rejuvenate.
Eh... about 10 minutes. I don't think I'm gonna attempt a rejuv unless I'm 100% sure it's not going to give me anything at all. I'll try it on the tester again, though.

Quote:
Originally Posted by Phil Nelson View Post
Sounds like an ion trap magnet
Nope! It's exactly what I thought it was: electromagnetic focus coil. It sez so in the Sams. It does have a trap magnet too...

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Originally Posted by jr_tech View Post
You could try a power-up with the rectifier (5U4) removed, to see if the excessive power draw is caused by the filter caps...you should be able to light up all of the (good) tube heaters, without drawing excessive wattage.
I might do that!

Also, I pulled all the tubes and tested them, of the 19 tubes, 8 or so are bad in one way or another. I think I have replacements, I'll have to check.
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  #17  
Old 09-14-2017, 08:21 AM
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Leave the tube on the tester for ~1 hour check back every 15 minutes. Wake up can be very slow.
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  #18  
Old 09-14-2017, 10:05 AM
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Quote:
Originally Posted by MadMan View Post
... (I think) an adjustable electromagnetic focus ring?...
The focus coil is adjustable so you can center the picture.

Agree about letting the CRT cook for an hour or more. You could try elevating the filament voltage to around 7 while it's cooking too.
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  #19  
Old 09-15-2017, 02:21 AM
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Sorry the pics suck bc cell phone. There's a splotch of tar on the front plate - petrified tape residue from another era. An auction sticker on the side in photo #2 gives away a tidbit of this piece's history. Though the seller says he got it from a friend, and had it as a display piece until he moved to a smaller dump.

I took the chassis out and evicted most of the dust bunnies. Inside, it seems only to be missing a single tube shield thingy. Haven't catalogued which tubes I need yet, I only know that I need lots. It's kinda hard looking underneath the chassis with a 100-pound tube weighing it down, but all looks original under there.

Any tips for removing the crt safely?

I don't think there's any waking it up, btw. Let it cook for an hour, still tests around "1." The scale is kind of ambiguous, but 0 to 2 is "Bad," so...
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File Type: jpg admiral12x12_1.jpg (85.8 KB, 46 views)
File Type: jpg admiral12x12_2.jpg (66.8 KB, 37 views)
File Type: jpg admiral12x12_3.jpg (83.5 KB, 56 views)
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  #20  
Old 09-15-2017, 08:26 AM
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Some testers good/bad indication is not always accurate. My B&K 466 will score some monochrome tubes middle of the bad scale when they still can produce a decent picture in a room with moderate lighting....Same tester will score color tubes that are dimmer in the low good range. It is always good to get to know your tester before using it to make decisions.

It may make a very decent picture with a brightener.
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  #21  
Old 09-15-2017, 03:50 PM
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Quote:
Originally Posted by MadMan View Post
Haven't catalogued which tubes I need yet, I only know that I need lots. ...
Tubes are usually not the main source of trouble in antique TV sets. What you should replace are all the wax paper capacitors and the electrolytic caps.
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  #22  
Old 09-15-2017, 04:30 PM
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Restoring Admiral T2301
 
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I've worked on a number of similar Admiral chassis. If the CRT is firmly attached, it's possible to leave it mounted and carefully tip the chassis on it's side to work on it. You may need to place a folder over towel or similar padding to help support and cushion the CRT
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  #23  
Old 09-16-2017, 03:28 AM
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Here's where I'm at: I changed the 3 filter caps, and it powers on without throwing a hissy fit, taking only 50 out of the theoretical 200 watts. The main transformer buzzes a little bit still. I'm not getting HV. I replaced 6SN7 (AF amp/sync clipper) and 12AU7 (sync amp/sync sep), which were bad. The only other bad ones (still in there) are audio out, damper, RF amp, and 1st video IF. The 2 tubes in the HV cage are both good, and filaments light up.

I just want to see if I can get a beam out of the crt. I really don't want to recap the whole thing only to find I need a flyback or something. Not to mention the crt.

Ideas?

http://www.earlytelevision.org/pdf/A...Sams_100-1.pdf

Last edited by MadMan; 09-16-2017 at 03:33 AM.
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  #24  
Old 09-16-2017, 09:34 AM
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You're very likely going yo have to do some recapping to get a raster. At least the horizontal oscillator and output circuit. Also this set uses a stacked B+ power supply design so the sound output tube needs to be biased correctly. Also make sure the speaker is pullged in as it's field coil doubles as a filter choke for the power supply.

I wouldn't worry about the flyback. I've never encountered a bad one. Also I[m local to you and have spare parts.
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  #25  
Old 09-16-2017, 09:45 AM
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Quote:
Originally Posted by MadMan View Post
Here's where I'm at: I changed the 3 filter caps, and it powers on without throwing a hissy fit, taking only 50 out of the theoretical 200 watts. The main transformer buzzes a little bit still. I'm not getting HV. I replaced 6SN7 (AF amp/sync clipper) and 12AU7 (sync amp/sync sep), which were bad. The only other bad ones (still in there) are audio out, damper, RF amp, and 1st video IF. The 2 tubes in the HV cage are both good, and filaments light up.

I just want to see if I can get a beam out of the crt. I really don't want to recap the whole thing only to find I need a flyback or something. Not to mention the crt.

Ideas?

http://www.earlytelevision.org/pdf/A...Sams_100-1.pdf
Did you have the speaker plugged in? It completes the B+ circuit!
It would seem that way, as the power consumption is only 50 watts.
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  #26  
Old 09-16-2017, 10:02 AM
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Also if the damper tube is bad there is no way in hell you'll get HV out of it.

Expect to replace some lytics, the paper caps in the horizontal section and any paper caps on the B+ boost line that the flyback supplies before HV materializes.
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  #27  
Old 09-16-2017, 10:09 PM
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Quote:
Originally Posted by bandersen View Post
Also make sure the speaker is pullged in as it's field coil doubles as a filter choke for the power supply.
Quote:
Originally Posted by dieseljeep View Post
Did you have the speaker plugged in? It completes the B+ circuit!
lol I thought the speaker was wired strangely!

Quote:
Originally Posted by Electronic M View Post
Also if the damper tube is bad there is no way in hell you'll get HV out of it.

Expect to replace some lytics, the paper caps in the horizontal section and any paper caps on the B+ boost line that the flyback supplies before HV materializes.
Thanks guys, I replaced the damper tube, and plugged in the speaker. Got a raster! It actually looks... not too bad given that it's all original (minus the filter caps). It lost it for a minute though, not really a big surprise, but it came back. I hadn't changed the damper tube because I thought I didn't have one! My dead-project RCA Victor tv DID have one though. Also the tube is surprisingly bright for testing 'bad.' Even in my brightly lit room, you could probably watch a show no problem.

brb recapping.
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Last edited by MadMan; 09-16-2017 at 10:25 PM.
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  #28  
Old 09-17-2017, 09:32 PM
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Cool! You're well on your way to having a fully working set Funny how a seemingly dead CT can produce a decent image.
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  #29  
Old 09-18-2017, 01:44 AM
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I recapped about 80% of it, I ran out of caps I needed, and I still need one tube, a 6BC5. I put a test pattern signal into it, and it honestly looked like crap. Now I wait for parts to come in.
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  #30  
Old 09-18-2017, 10:52 AM
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Hmm. I don't see a 6BC5 in the schematic. I'm thinking it's in the tuner but that shows a 6AG5. Perhaps is a production run change ? If it is in the tuner and is bad, for sure it would result in a crappy picture.
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