Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Jun Mon 25, 2018 9:19 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 27 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Admiral 20A1 recap - Need Advise
PostPosted: Feb Sat 24, 2018 2:24 am 
Member

Joined: May Sun 07, 2017 11:35 am
Posts: 283
The set will run without the width coil. You could then scope around to find a candidate for the ref pulse.


Top
 Profile  
 
 Post subject: Re: Admiral 20A1 recap - Need Advise
PostPosted: Feb Sat 24, 2018 3:29 am 
Member
User avatar

Joined: Mar Sun 01, 2009 10:27 pm
Posts: 4518
Location: Ann Arbor, MI
robert1 wrote:
this is why i asked if i could replace the coil with a standard width coil & try to find another source for the horizontal sync pulse. i notice that the later Admiral chassis designs use a different method of sourcing the sync pulse

One problem with using a standard width coil is getting one with the right inductance. Now if schematic for your set specifies the inductance, than you could try to get a new coil to match. Or you could try whatever you can find and see if it works. You could always wind a new secondary on to a standard coil. The secondary would not have to be precision wound and would not have many turns.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: Admiral 20A1 recap - Need Advise
PostPosted: Feb Sat 24, 2018 4:53 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 133
Location: parkersburg west virginia
Tom Schulz wrote:
robert1 wrote:
this is why i asked if i could replace the coil with a standard width coil & try to find another source for the horizontal sync pulse. i notice that the later Admiral chassis designs use a different method of sourcing the sync pulse

One problem with using a standard width coil is getting one with the right inductance. Now if schematic for your set specifies the inductance, than you could try to get a new coil to match. Or you could try whatever you can find and see if it works. You could always wind a new secondary on to a standard coil. The secondary would not have to be precision wound and would not have many turns.


Both the Sams & Riders manuals do not specify the inductance, but Sams shows it as 80 ohms for the Primary & .5 ohm for the secondary.
i really don't have any parts like that here so i would have to look (& guess) online for something that might be close.
as for the the winding, can it be wrapped around the outside of the width coil winding?


Top
 Profile  
 
 Post subject: Re: Admiral 20A1 recap - Need Advise
PostPosted: Feb Sat 24, 2018 7:33 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 289
Location: Elkhorn,Wisconsin,United States
Hi Robert,
I did some checking on 20b1 set I have, and found that the primary inductance adjusts in the 9 to 12 mh range. The secondary adjusts through 530 uh. I took these readings with the wires removed from the coil. Also remember that the adjusting core of the coil increases overall inductance. I noticed that the secondary coil is wound with heavier wire, 26 to 28 gauge wire. I measured 78.8 ohms for the primary winding.
If you get a standard replacement coil , it shouldn't be too much trouble to wind the secondary over the primary. Just try and count the secondary turn off the original coil.
Ed


Top
 Profile  
 
 Post subject: Re: Admiral 20A1 recap - Need Advise
PostPosted: Feb Mon 26, 2018 7:21 pm 
Member
User avatar

Joined: May Fri 29, 2009 4:35 am
Posts: 2041
Location: Chicago, IL USA
Perhaps this Workman T121 width coil available from Talon will work ?

http://www.talonix.com/shop/item.aspx?itemid=3660

Chassis mount, Transformer,
Primary resistance 102 ohms,
Primary Inductance 9 - 24 mH

Secondary (AGC winding) resistance 1.2 ohms
Secondary Inductance .25-1.1 mH


Top
 Profile  
 
 Post subject: Re: Admiral 20A1 recap - Need Advise
PostPosted: Feb Mon 26, 2018 9:12 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 133
Location: parkersburg west virginia
bandersen wrote:
Perhaps this Workman T121 width coil available from Talon will work ?

http://www.talonix.com/shop/item.aspx?itemid=3660

Chassis mount, Transformer,
Primary resistance 102 ohms,
Primary Inductance 9 - 24 mH

Secondary (AGC winding) resistance 1.2 ohms
Secondary Inductance .25-1.1 mH


Wow, Thanks, Bob. i believe that may fix it. i just ordered it. i will post back on this topic once i get it installed (which may be a couple of weeks)


Top
 Profile  
 
 Post subject: Re: Admiral 20A1 recap - Need Advise
PostPosted: Jun Mon 25, 2018 6:08 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 133
Location: parkersburg west virginia
Hi
I finally got around to working on this set around three weeks ago. i got that part from Tylon electronics over a month ago.
after installing this coil & powering it up, i got the raster back, however, i noticed that i had some serious fold over on the right side of the screen. adjusting the horizontal drive did not help at all.
I then remembered watching one of Bob Anderson's video of servicing a similar chassis, & decided to check that 7500 ohm 25 watt resistor. sure enough, it was open. i got another one from Mouser (It was half the size), & i had to buy the proper size screws so i could mount it in the same place & way as the original.
I powered the set up, & got a much uniform raster.
I then connected the cable that i have with a channel-3 output to it & i immediately got sound out of the speaker. the picture, however, was weak. when i grasped the tuning knob, i noticed that it made lots of noise in the picture. i found that if i grasp the turret & slightly turn it off the detent, my picture quality would increase, apparently, i am going to have to deal with the tuner...But, here's another problem. i don't think that the coil that i installed works well with the horizontal sync circuits as this is what i am getting on the screen.
Image

Image

This is where the horizontal locks at. it will not drift, even after a half hour warm-up. I also notice that the width is still a little wide.
I suspect that the coil that i installed may be causing this as the ratings on the secondary of that coil are different then that of the original.


Attachments:
Admiral 20A1-6.JPG
Admiral 20A1-6.JPG [ 62.17 KiB | Viewed 3 times ]
Admiral 20A1-8.JPG
Admiral 20A1-8.JPG [ 177.27 KiB | Viewed 3 times ]
Top
 Profile  
 
Post New Topic Post Reply  [ 27 posts ]  Moderators: 7jp4-guy, Mr. Detrola Go to page Previous  1, 2

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB