Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Vintage TV & Radio Tech Forum

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 06-26-2017, 10:24 PM
VintagePC's Avatar
VintagePC VintagePC is offline
Tube bug got me 05/2010
 
Join Date: May 2010
Posts: 535
Replacing a flyback?

Apologies for the double post.

Maybe I didn't get an answer because I asked in a more narrow sub-forum so trying here, since I have a hard time believing nobody here has ever replaced a flyback with an aftermarket jobbie

Long story short, I'm swapping in an HVO-7 and am uncertain about how to connect it. I have the original schematic and a copy of the installation guide.
See here: http://www.videokarma.org/showthread...34#post3185934

All provided schematics are variations on that circuit, with either B+ or Boost as the power source for the secondary. I think this circuit is closest to my original one:





However, there are still some pretty significant changes, if I'm understanding this right.

Tap mappings, from what I've puzzled out:
Old tap 9 is now 2
Old tap 8 is now 1
Old HV rect cap had no number, now 3.
Old tap 7 is now 6
Old tap 5 is now 8
Old tap 4 is now 5
Old tap 3 is now ??? (What's the purpose of the lead to the VBO coil? phase/feedback?)

Am I right in that I need to:
1. Change the taps the width coil spans, from 3/4 to 5/8
2. Move the damper filament from (old) tap 4 to the damper cathode.
3. Disconnect the center tap of the linearity coil, and tie the midpoint of the linearity caps (old tap 7) to new tap 6 and the damper cathode (as a source of boosted B+)

Where I'm getting even more confused is the remark to remove the boost from the damper plate. In the alternate version of this (with B+ swapped for boost) as well, new tap 6 and the damper plate connection make note of the same source. However, in my circuit, old tap 7 is attached to boost, and the damper plate (not DC Coupled) is on B+ (differing sources). So what do I do?

->I *think* it's is moving the damper plate to tap 4 instead of B+, moving the yoke to new tap 6. That just leaves the VBO connection on old tap 3...

Or am I completely going about this the wrong way, and is it as simple as mapping the old -> new taps and leaving well enough alone? (based on where they go)
7->6
5->5
4->8
3->5
Attached Images
File Type: png 33-4.png (70.9 KB, 67 views)
Reply With Quote
  #2  
Old 06-30-2017, 09:57 AM
bandersen's Avatar
bandersen bandersen is offline
Restoring Moto VT71s
 
Join Date: Mar 2009
Location: Chicago, IL
Posts: 7,230
I would map the old to new and give it a try.

Regarding the purpose of the old tap 3 going to the vertical oscillator. I believe that is the boost voltage.
__________________
Here are my Vintage Radio & TV YouTube Channel and Photo Gallery
Reply With Quote
  #3  
Old 06-30-2017, 10:03 PM
VintagePC's Avatar
VintagePC VintagePC is offline
Tube bug got me 05/2010
 
Join Date: May 2010
Posts: 535
Thanks Bob, I'll give it a go and see.
Reply With Quote
  #4  
Old 07-01-2017, 05:20 PM
VintagePC's Avatar
VintagePC VintagePC is offline
Tube bug got me 05/2010
 
Join Date: May 2010
Posts: 535
Gave it a go. First attempt produced no HV at all. Figured I had it out of phase, and swapped the wires. This time I got HV, but it's pretty dim and there's about 1/3 of the image folded over on the left.

Guess that means it's not a drop-in and that rewiring is necessary. Don't want to go down that route given how the original fly still seems to be working ok after doping it.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:36 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
ęCopyright 2012 VideoKarma.org, All rights reserved.