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


It is currently Aug Wed 21, 2019 9:03 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 24 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Admiral 12x12 - Newbie
PostPosted: Jun Fri 21, 2019 4:30 am 
Member

Joined: May Thu 14, 2015 4:15 pm
Posts: 1659
Location: Dallas, TX
Good question.
B+ from the power supply, fuse M4, flyback winding and width coil, damper, Horizontal Linearity coil, R77, vertical output transformer, etc.
On some designs, after the horizontal output is working the voltage at R77 and the width coil is higher than B+, because of the AC voltage developed on the flyback winding and the damper acting as a rectifier, this voltage is called Boost.

_________________
Tim
It's not the Destination, It's the Journey.


Top
 Profile  
 
 Post subject: Re: Admiral 12x12 - Newbie
PostPosted: Jun Fri 28, 2019 3:03 am 
Member

Joined: Mar Fri 28, 2014 10:04 pm
Posts: 42
Location: St. Louis, MO
Got it (mostly) working!

I ended up replacing the vertical linearity pot. I think it may have been shorting to ground under load. It tested find on the bench, though. It also helped a lot to adjust the vertical linearity and height by looking at the waveforms on my scope, and then adjusting the vertical sync to match.

I appreciate all the useful thoughts and suggestions!

Roger


Attachments:
working1.jpg
working1.jpg [ 202.64 KiB | Viewed 140 times ]
Top
 Profile  
 
 Post subject: Re: Admiral 12x12 - Newbie
PostPosted: Jun Fri 28, 2019 4:11 am 
Member
User avatar

Joined: May Fri 29, 2009 4:35 am
Posts: 2126
Location: Chicago, IL USA
Nice job! One thing though. The image shouldn't fill the whole CRT vertically. The old NTSC aspect ratio is 4:3 and with this model they used what's known as a "double-D" mask. That's where the image fills out fully horizontally but it's masked off vertically.


Top
 Profile  
 
 Post subject: Re: Admiral 12x12 - Newbie
PostPosted: Jun Fri 28, 2019 7:13 pm 
Member

Joined: Mar Fri 28, 2014 10:04 pm
Posts: 42
Location: St. Louis, MO
I was wondering a little about that. It should be an easy fix with the height adjustment pot. I still want to do a final check out before I put everything back in the cabinet.

At this stage, I was just happy to get a working picture. The circuit around the vertical output tube had been giving us trouble for days. I was worried that the vertical output transformer or yoke was bad, so it's a relief to see a usable image.


Top
 Profile  
 
Post New Topic Post Reply  [ 24 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 2 guests



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB