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 11-21-2017, 08:41 AM
timmy's Avatar
timmy timmy is offline
VideoKarma Member
 
Join Date: Jan 2011
Location: ferndale ny
Posts: 3,504
RCA cd197 36inch color

Ok I have this RCA cd197 color and its from 1996 works great but they are known for flybacks every few years but for awhile now while watching the screen flickers bright and the images have a blue smear on them then it will be normal but does this at random so the question is that is there anyone that has had something similar to this problem. Maybe a bad cap on the neck board I really don't know but the set works great and I want to try and track down a cause and fix it. Any ideas would be great.
Reply With Quote
  #2  
Old 11-21-2017, 10:45 AM
dieseljeep dieseljeep is offline
VideoKarma Member
 
Join Date: Jul 2010
Posts: 7,562
Quote:
Originally Posted by timmy View Post
Ok I have this RCA cd197 color and its from 1996 works great but they are known for flybacks every few years but for awhile now while watching the screen flickers bright and the images have a blue smear on them then it will be normal but does this at random so the question is that is there anyone that has had something similar to this problem. Maybe a bad cap on the neck board I really don't know but the set works great and I want to try and track down a cause and fix it. Any ideas would be great.
Intermittant H-K short in blue gun of CRT.
Reply With Quote
  #3  
Old 11-21-2017, 11:57 AM
timmy's Avatar
timmy timmy is offline
VideoKarma Member
 
Join Date: Jan 2011
Location: ferndale ny
Posts: 3,504
Quote:
Originally Posted by dieseljeep View Post
Intermittant H-K short in blue gun of CRT.
Is there a way to try to eliminate it without a crt tester for that tube. Or maybe modify a tester I have here to maybe clear the short. Or a separate heater source.
Reply With Quote
  #4  
Old 11-21-2017, 03:44 PM
zeno's Avatar
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 4,672
May not be CRT. You can tap the neck & see if it comes & goes
but you also shake the CRT board.
Most sets the filament comes off the FBT & one side goes to ground.
You have to lift it above ground & if its grounded in the FBT
out of luck. Also when you get a H-K short USUALLY the K goes
to 0 V & lights up bright the bad color then set goes into
shut down.

Another test is lift the blue K & one of the others. run jumpers to
swap the K's & see if the blue still acts up or it goes over to
the other color. Do it with a B&W pix to save confusion !!

Sears had a crap load of 19" Sanyos with Sylvania jugs shorting.
Cure was get the filament above ground & add a 1.5 meg & .001
cap but I dont remember where ! IIRC the resistor went from the bad K
to filament but dont remember where the cap went

BTW someone used to make an isolation booster that worked on
the sweep freq. You would wire it for no boost.
Maybe Brian remembers ?

73 Zeno
LFOD !
Reply With Quote
  #5  
Old 11-21-2017, 04:16 PM
timmy's Avatar
timmy timmy is offline
VideoKarma Member
 
Join Date: Jan 2011
Location: ferndale ny
Posts: 3,504
Well upon turning on it flickers bright then normal but when it gets bright the edges are blue and smeared and turning it on as the crt lights up there is a lot of blue then after a minute the blue calms down then flickers from time to time and other times it won't flicker. So I did think it may be a cap on the neck board and the fly is 2 years old or another cap in another area of the board. The set never went into shut down.
Reply With Quote
Audiokarma
  #6  
Old 11-21-2017, 06:00 PM
tom.j.fla tom.j.fla is offline
VideoKarma Member
 
Join Date: Aug 2014
Location: Dover,Fl
Posts: 250
Timmy, going to need to know the chassis number. Most likely starts with "CTC-XXX",the x's meaning the three numbers also include any letters and numbers that follow. Zeno you isolate the fly winding from circuit ground that feeds the crt heater, the resistor feeds B+ to the heater to prevent any arching from happening. If heater winding feeds any other circuit then you need to add another winding that is not at ground. All the best,Tom.J
Reply With Quote
  #7  
Old 11-21-2017, 06:07 PM
timmy's Avatar
timmy timmy is offline
VideoKarma Member
 
Join Date: Jan 2011
Location: ferndale ny
Posts: 3,504
Quote:
Originally Posted by tom.j.fla View Post
Timmy, going to need to know the chassis number. Most likely starts with "CTC-XXX",the x's meaning the three numbers also include any letters and numbers that follow. Zeno you isolate the fly winding from circuit ground that feeds the crt heater, the resistor feeds B+ to the heater to prevent any arching from happening. If heater winding feeds any other circuit then you need to add another winding that is not at ground. All the best,Tom.J
Ok the tag shows ctc197cd .
Reply With Quote
  #8  
Old 11-21-2017, 06:27 PM
Sandy G's Avatar
Sandy G Sandy G is offline
Spiteful Old Cuss
 
Join Date: May 2003
Location: Rogersville, Tennessee
Posts: 9,571
All these ills the last bunch of CRTs develop- I had a 36 Magnavox that would flicker & zone out after awhile, & a 36" Sony that also had a bunch of funky weirdness after it had a few years on it.... I NEVER have heard 1st or 2nd round of color crts pulling stuff like the latter day tooobs did- Had quality slipped THAT badly ? Part of the reason I got a 36" Sony was the Trinitrons HAD BEEN the Gold Standard for so long...It was almost painful to see..One gun-Usually the Red would crap out- & you may as well turn the sumbich off & go beat the cat, the wife, the dog, whatever.... Cause you wasn't gonna watch no more TV on IT for awhile...I dunno about the rest of youse guys, but I would have rather HAPPILY paid a little more dinero if I coulda bought a 36" CRT built to, what,1975 or so standards... Or whenever they started makin' them so cussedly CHEAP... I tell my "Civilian" friends that they about had HDTV color in 1954- & tell'/em to check out an early set that had been all properly set up by someone who knew what they were doing...Too bad they never really made "Milspec" color CRTs...
__________________
Benevolent Despot
Reply With Quote
  #9  
Old 11-21-2017, 11:32 PM
irext's Avatar
irext irext is offline
VideoKarma Member
 
Join Date: Dec 2016
Posts: 69
A quick easy way to isolate it is to disconnect the normal CRT heater path and run a loop or two of hookup wire around a convenient part of the FBT ferrite core, keeping it well away from the HV overwind, and connect this to the CRT filament. You can judge how many turns around the FBT by looking at the color of the CRT filament glow. If the fault doesn't return then you can safely assume it's an intermittent heater to cathode short on the blue gun. I've used this method many times to revive otherwise uneconomical set repairs. If the tube is faulty you've got nothing to lose. Sony Trinitrons were very prone to CRT H/C shorts. If the fault is still present then you've isolated the CRT.
Reply With Quote
  #10  
Old 11-22-2017, 12:13 AM
Sandy G's Avatar
Sandy G Sandy G is offline
Spiteful Old Cuss
 
Join Date: May 2003
Location: Rogersville, Tennessee
Posts: 9,571
Quote:
Originally Posted by Sandy G View Post
All these ills the last bunch of CRTs develop- I had a 36 Magnavox that would flicker & zone out after awhile, & a 36" Sony that also had a bunch of funky weirdness after it had a few years on it.... I NEVER have heard 1st or 2nd round of color crts pulling stuff like the latter day tooobs did- Had quality slipped THAT badly ? Part of the reason I got a 36" Sony was the Trinitrons HAD BEEN the Gold Standard for so long...It was almost painful to see..One gun-Usually the Red would crap out- & you may as well turn the sumbich off & go beat the cat, the wife, the dog, whatever.... Cause you wasn't gonna watch no more TV on IT for awhile...I dunno about the rest of youse guys, but I would have rather HAPPILY paid a little more dinero if I coulda bought a 36" CRT built to, what,1975 or so standards... Or whenever they started makin' them so cussedly CHEAP... I tell my "Civilian" friends that they about had HDTV color in 1954- & tell'/em to check out an early set that had been all properly set up by someone who knew what they were doing...Too bad they never really made "Milspec" color CRTs...
- Sandy G.
__________________
Benevolent Despot
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 04:28 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.