Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Dec Wed 01, 2021 2:43 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 45 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject: Re: Admiral 20X1 Excessive Width
PostPosted: Aug Sat 28, 2021 3:13 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 854
Location: Crystal Bay, NV
Fisrt thing I thought of was the yoke too far back.
If you loosen the wing nut, the yoke will slide back and forth a little. Make sure it is as far forward as possible.
=====
Ron


Last edited by TahoeTV on Aug Sat 28, 2021 4:43 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Admiral 20X1 Excessive Width
PostPosted: Aug Sat 28, 2021 3:40 am 
Member

Joined: Apr Thu 14, 2016 8:25 pm
Posts: 515
Location: pensacola fl
Hi all. A couple of things are your filament and B+ too high? If not has either the yoke or flyback been replaced? If so are they the correct ones. If your screen resistor on the 6BG6 is correct then i would move over to the damper tube circuit. On many sets there is a capacitor across the damper from cathode to plate. Usually if the set was in a low line voltage area one could add a second cap there or replace the cap there with a larger one to open up the width. Some sets had no cap there and if one was added the screen width increased. So you may have a reverse situation here. If a cap is there is it the right value? These were usually 4-6KV ceramic disc with values like 150PF. You may have to reduce it or even unhook it. Try this area. It was not considered a modification to some set makers to change this value, in fact a call to some set makers resulted in them telling a tech what to do as far as value was concerned.

hope this helps.


Top
 Profile  
 
 Post subject: Re: Admiral 20X1 Excessive Width
PostPosted: Aug Sat 28, 2021 9:21 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 12009
Location: San Jose, CA USA
My Admiral has the 20A1 chassis, which is not identical, but pretty similar. I don't feel like pulling out the chassis right now, so I can't check the drive amplitude right now, but here I've adjusted the width from where I had it (core basically fully in, for max width) and fully out for minimum width. You can see there is something like a full inch of difference in width between the two.

Attachment:
IMG_2102.JPG
IMG_2102.JPG [ 625.57 KiB | Viewed 318 times ]


Attachment:
IMG_2103.JPG
IMG_2103.JPG [ 647.73 KiB | Viewed 318 times ]


Since I'm running it with the core near fully inserted, I clearly don't have a problem with excessive width on mine.

_________________
Tom K6VL


Top
 Profile  
 
 Post subject: Re: Admiral 20X1 Excessive Width
PostPosted: Aug Sun 29, 2021 4:24 am 
Member

Joined: Oct Fri 28, 2011 7:27 pm
Posts: 115
Location: New York, NY
Tom Albrecht wrote:
My Admiral has the 20A1 chassis, which is not identical, but pretty similar. I don't feel like pulling out the chassis right now, so I can't check the drive amplitude right now, but here I've adjusted the width from where I had it (core basically fully in, for max width) and fully out for minimum width. You can see there is something like a full inch of difference in width between the two.

Attachment:
IMG_2102.JPG


Attachment:
IMG_2103.JPG


Since I'm running it with the core near fully inserted, I clearly don't have a problem with excessive width on mine.


Tom, thanks for doing that - now I have a reference point for what it should be doing.

As recently suggested, I think my next step will to look back into those odd traces with the large beats/spikes. I'll try next undoing the retrace mods and if they are still there then try to figure out what's causing that.

Thanks again for all of the help!

FK


Top
 Profile  
 
 Post subject: Re: Admiral 20X1 Excessive Width
PostPosted: Sep Mon 13, 2021 7:09 pm 
Member

Joined: Oct Fri 28, 2011 7:27 pm
Posts: 115
Location: New York, NY
I spent a bit more time and replaced a few more (just slightly) out of spec resistors and a few low value caps and no change. So basically here's where it is at...

Other than just width there are other (likely related) horizontal issues. Doing the horizontal oscillator adjustment is somewhat not straightforward because it's quite difficult to get the thing to lose horizontal lock. I have to back out the coil and the lock range quite a bit past where it says to start to even get it to go out of horizontal sync, and even then sometimes it'll only lose it when the knob is fully clockwise and I change channels and go back. Otherwise the horizontal hold seems to affect the horizontal center/position of the image and also linearity.

For example, you can kind of see in the portrait video boxing on this show, how adjusting the horizontal hold shifts the picture and also affects linearity. There is maybe some place in the control's rotation where linearity looks best, but a little squirrely for sure:
https://youtu.be/1kkJKU9c-hI

And there's still that foldover (I think that's what it is?) line that also seems to follow the image shifting with horizontal hold:
https://youtu.be/N4IiO41ujic

I know this issue has been around the block and back and whatever the it is, is illusive, but adding these videos just in case it might ring a bell or something!

Thanks again for all of the help and great suggestions.

FK


Top
 Profile  
 
Post New Topic Post Reply  [ 45 posts ]  Moderators: Mr. Detrola, 7jp4-guy Go to page Previous  1, 2, 3

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 10 guests



Search for:
Jump to:  




































Privacy Policy :: Powered by phpBB