Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Solid State CRT Televisions

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 07-15-2017, 11:58 AM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
OSD shows before the picture fades in

Has anyone seen anything quite like this?

https://www.youtube.com/watch?v=4nLCLiLmsTc

If I turn the set off and immediately back on, the OSD comes up instantly as expected, but once again, the picture itself remains black for a few seconds before slowly fading in.

I'm assuming the OSD is just sent to the picture tube as instant as the TV starts up, and something is slowly ramping up the brightness to the picture perhaps, in the jungle IC?
Reply With Quote
  #2  
Old 07-15-2017, 12:10 PM
Eric H's Avatar
Eric H Eric H is offline
Administrator
 
Join Date: Jun 2002
Location: So. Calif
Posts: 11,149
Maybe the green gun warms up a little faster than the others?
Reply With Quote
  #3  
Old 07-15-2017, 12:20 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
Quote:
Originally Posted by Eric H View Post
Maybe the green gun warms up a little faster than the others?
Hmm, not entirely sure.. Just tried this, forcing the OSD to show red, and both the red and green OSD comes up well before the picture comes in, and the picture is showing a very vibrant Match Game floor.

https://www.youtube.com/watch?v=GxlgPUtjjGg
Reply With Quote
  #4  
Old 07-15-2017, 12:26 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
Update: I clipped on an oscilloscope to the green signal going to the tube, and sure enough, the OSD is there the moment the TV is turned on, but nothing else until after a few seconds then slowly rises.

I've never seen anything quite like that.
Reply With Quote
  #5  
Old 07-15-2017, 01:07 PM
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 2,701
My guess is..........
The set uses AKB or Auto Kine Bias. First used in RCA's IIRC.
The jungle IC has the circuit in it. It measures beam current
by firing each gun during blanking then adjusts the grey scale.
The OSD probably takes a different rout.
Some sets like Sony will not display a raster until its warmed
up & grey scale is good. Bad news is if the jug starts getting
weak the raster will blink on & off.

BTW if a set has AKB you can usually collapse the vert a little & see
3 color stripes at the top. Thats the guns getting fired.

73 Zeno
LFOD !
Reply With Quote
Audiokarma
  #6  
Old 07-15-2017, 01:49 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
That might be what it is, certainly sounds plausible..
Reply With Quote
  #7  
Old 07-15-2017, 02:47 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 4,143
Sometimes on a set with AKB, it will do the opposite, and you will see the guns come on with too much drive (because the emission is low until the cathodes warm up and also because the filter capacitors in the AKB circuit need to charge up), and then get turned down (although the fact that the cathodes are warming up at the same time keeps it from being too bright). I had a Zenith in which the three guns reached equilibrium with slightly different delays, so the gray scale had three noticeable adjustments occur, one after another.

Maybe this could also be a channel change / source change blanking of some kind that happens to operate when first turned on? Would be interesting to see what it does when switching between sources or changing RF channels.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
  #8  
Old 07-15-2017, 03:20 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
Quote:
Originally Posted by old_tv_nut View Post
Sometimes on a set with AKB, it will do the opposite, and you will see the guns come on with too much drive (because the emission is low until the cathodes warm up and also because the filter capacitors in the AKB circuit need to charge up), and then get turned down (although the fact that the cathodes are warming up at the same time keeps it from being too bright). I had a Zenith in which the three guns reached equilibrium with slightly different delays, so the gray scale had three noticeable adjustments occur, one after another.

Maybe this could also be a channel change / source change blanking of some kind that happens to operate when first turned on? Would be interesting to see what it does when switching between sources or changing RF channels.
Hmm, changing sources causes a "fade in" for each input..

Also I have noticed a quirk, if the picture is bright, like a daytime scene in a movie, then goes to a night scene with a fast cut, the picture looks for a split second like the brightness is up too high, and then fades down to a proper looking picture.

I'll see if I can capture that.
Reply With Quote
  #9  
Old 07-15-2017, 03:29 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
Here's the fading, at least from bright to dark scenes: https://www.youtube.com/watch?v=2Si6LAZJ36Y

EDIT: Huh, apparently in slow motion, you can hear that the microphone on my phone picked up the horizontal sweeping noise from the TV. Never knew the mic on it was that sensitive. lol
Reply With Quote
  #10  
Old 07-15-2017, 04:43 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 4,143
Looks like a long DC restoration time constant.

Edit: Does it happen the other way when going from a dim scene to a bright one? Simple diode DC restorers will be asymmetrical, gated clamps will not.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote
Audiokarma
  #11  
Old 07-15-2017, 05:26 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
Quote:
Originally Posted by old_tv_nut View Post
Looks like a long DC restoration time constant.

Edit: Does it happen the other way when going from a dim scene to a bright one? Simple diode DC restorers will be asymmetrical, gated clamps will not.
It does, when it goes from dark to bright, you can see for a split second the brightness ramping up.
Reply With Quote
  #12  
Old 07-18-2017, 09:47 AM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
And a second weird effect, though not as weird as I have certainly seen this before. The OSD is not affected by the brightness or contrast settings in the menu. I can turn then both down to zero, and have no TV picture, but the OSD is still there bright as it ever was.
Reply With Quote
  #13  
Old 07-18-2017, 07:19 PM
Findm-Keepm's Avatar
Findm-Keepm Findm-Keepm is offline
Followin' the Rules...
 
Join Date: Jun 2007
Posts: 2,667
Once again, those Apex TVs were never star performers.....what's the jungle chip part numbrt? With no schematic or chassis info, it's all just guessing.

Post a chip complement and I can dig through some notes, but without some meat, it's all just guesses....
__________________
Brian
USN RET (Avionics / Cal)
CET- Consumer Repair and Avionics ('88)
"Capacitor Cosmetologist since '79"

When fuses go to work, they quit!.
Reply With Quote
  #14  
Old 07-18-2017, 09:30 PM
Eric H's Avatar
Eric H Eric H is offline
Administrator
 
Join Date: Jun 2002
Location: So. Calif
Posts: 11,149
Quote:
Originally Posted by lnx64 View Post
I can turn then both down to zero, and have no TV picture, but the OSD is still there bright as it ever was.
If you could turn the OSD down how would you find the menu to turn the brightness back up?

Every set I've ever seen with an OSD worked this way.
Reply With Quote
  #15  
Old 07-19-2017, 11:54 AM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: Oviedo, FL
Posts: 1,525
Quote:
Originally Posted by Eric H View Post
If you could turn the OSD down how would you find the menu to turn the brightness back up?

Every set I've ever seen with an OSD worked this way.
Then I have a Philips Magnavox for you. It goes down with the picture, but zero brightness and contrast doesn't make the entire picture disappear, just dark.
Reply With Quote
Audiokarma
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 09:53 PM.



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