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 Post subject: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Thu 16, 2019 4:29 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 957
Location: Southwestern,Ontario Canada
Now that I've picked up my second 24A12X Admiral tv, I'm getting around to re-capping. I have a question about Capacitor C60 and it's value. It is a Damper filter capacitor and it is rated at .035 @ 600 volt. I've checked both chassis's and they both use the same value cap. I need to put in a cap order, but I currently have .03 @ 600v and .04@ 600v. on hand. Seeing as they must have picked this value for a reason, and is a non standard value now. (.033 and .036) of which Justradios happens to be out of (.036). at least in the yellow poly variety. Both of these sets also have the C58 Horizontal Output Cathode bypass cap upgraded from .1@ 600v to .2@ 600v. That kind of thew me until I saw it in the notes. As these sets are Canadian and have the large 25 Hz transformers there are also addition changes that the 24A12 60 hz sets don't have. There are 3 additional electrolytics under the chassis 2 are rated at 20 mfd@ 450v and 1 at 4mfd@50v. There might be other changes I haven't spyed yet. Both sets have all original parts except for 1 that has had the vertical output transformer replaced a long time ago. I believe the X after the 24A12 must designate 25 Hz. Also, Ron, the Canadian schematic go-to guy looked and does not have the Canadian version of the schematic so I am going by the Sams 24A12 from the ETF website.

http://www.earlytelevision.org/pdf/admi ... ams_77.pdf

Interestingly, I checked the 2 paper looking electrolytics 20 mfd @ 450v ,500v surge and they test at almost 78 mfd.
Also, pure ammonia out of the bottle on a cloth is excellent for cleaning the crud from the cabinet.
Tony


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Admiral3.JPG
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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Thu 16, 2019 4:51 pm 
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Joined: May Sun 07, 2017 11:35 am
Posts: 573
Location: Belrose, NSW, Australia
That's the boost cap. Its value is not that critical, variations may affect the horizontal linearity slightly. I'd go for a .039uF 630v since that's the nearest preferred value. If not, I'm sure a .033 or a .047 will work just fine. But choose a physically large cap, it carries a lot of current.

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Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Thu 16, 2019 5:52 pm 
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Location: Chicago, IL USA
Ammonia is one of the worst things to clean bakelite with. It can damage and dull the thin shiny surface.

Check this out for cleaning and polishing tips.

http://dolledupdesirae.blogspot.com/201 ... talin.html


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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Thu 16, 2019 7:06 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 957
Location: Southwestern,Ontario Canada
I'm not experiencing any dulling of the surface. Quite the opposite, it shines like new.
Tony


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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Thu 16, 2019 11:28 pm 
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Location: Fernandina Beach, FL
Tony F wrote:
Now that I've picked up my second 24A12X Admiral tv...I believe the X after the 24A12 must designate 25 Hz. ...
Tony


That power transformer screams "25 CPS" to me!

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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 4:46 pm 
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Location: Southwestern,Ontario Canada
I thought I would describe how I was able to remove the "speed clips" that Admiral used on these bakelite sets without mangling the clips or breaking off a bakelite posts. Using a pair of needle nose pliers and some small finishing nails you need to get the point of the nail between the razed section of the clip that grips the post. Then using a small hammer tap the end of the nail while gripping the nail with the pliers. You don't want to try to get the nail right though to the other side of the clip, but just enough with 2 nails installed to re-leave the tension of the clip against the post. You have to angle the nails so that they miss the post and don't go straight into it. I found that by just doing the one side was enough to allow you to get a pair of needle-nose pliers under the clip to work it off. I used a pair of bent pliers, that would allow a little more room to work than a regular pair would. By doing this, the clips just slid right off. I hope this helps some people in the future.The other photos show that the set is 25 Hz only as well as the 2 different serial numbers.
Tony


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25Hz1.jpg
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25Hz2.jpg
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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 4:56 pm 
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Location: Phoenix, Arizona
Thanks for the clip tip.

I have an admiral 7" in a Bakelite cabinet and I need to remove the plastic window which is quite foggy and replace it with a better one. When I removed the better one from a somewhat broken cabinet I busted off all the posts and decided to not work on the current cabinet.

Jim


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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 5:40 pm 
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Location: Fernandina Beach, FL
That's a better idea. I have a 26R12 and choose to NOT remove my speaker board. I may "revisit" that now.

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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 6:17 pm 
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Location: Southwestern,Ontario Canada
As for the 7" sets, (I'd be a lot more careful) with the posts being smaller you might consider something like a large darning needles. I've also used dental picks to get under the burr on the clips. The problem with this style of speed clip that Admiral used, is fairly rigid and does not have a large "cut" in it, at the burr to make it fairly flexible. Some other smaller clips seem to allow the insertion of types of hardware to take the pressure off the contact point of the burr.
Tony


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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 8:24 pm 
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Joined: Sep Fri 07, 2007 2:27 am
Posts: 6082
Location: Grand Chute, Wisconsin
Or you could use a speed nut removal tool.

Attachment:
Tinnerman nut remover.jpg
Tinnerman nut remover.jpg [ 87.12 KiB | Viewed 339 times ]


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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 8:35 pm 
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wiscojim wrote:
Or you could use a speed nut removal tool.

And where, Pray Tell Jim, do you suppose that we could buy one??? :wink:

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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 8:38 pm 
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Joined: Sep Fri 07, 2007 2:27 am
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Location: Grand Chute, Wisconsin
Don Cavey wrote:
wiscojim wrote:
Or you could use a speed nut removal tool.

And where, Pray Tell Jim, do you suppose that we could buy one??? :wink:

The ends are merely stiff springs. I would think it would be easy to build one after a trip to the local hardware store.

.


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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Sat 18, 2019 11:21 pm 
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Location: Fernandina Beach, FL
wiscojim wrote:
Don Cavey wrote:
wiscojim wrote:
Or you could use a speed nut removal tool.

And where, Pray Tell Jim, do you suppose that we could buy one??? :wink:

The ends are merely stiff springs. I would think it would be easy to build one after a trip to the local hardware store.

.


:wink:

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 Post subject: Re: Admiral 24A12X "Big Bakelite" Cap question
PostPosted: May Fri 24, 2019 12:51 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 957
Location: Southwestern,Ontario Canada
I came across these (what look like ceramic caps) in parallel with R89 the 7500 ohm 25 watt wire wound power resistor. They look original and measure at 116 pf individually or about 60 pf in series. This is part of the 6W4, V18 Damper tube circuit. Any idea why they were installed and if I should leave them installed ? The other identical chassis I have does not have them.
Tony


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R89caps1.jpg
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R89caps2.jpg
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