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
  #31  
Old 11-27-2018, 08:06 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
OK So I did not have the cathode and filament tied together. I fixed this and the cathode current is a bit more normal now. I was going to adjust the hor linearity coil so I put the plate cap back on top of the h output tube and BOY the hv got me. I will say it doesnt have near as much as a bite as getting bit by my 87 TBird doing the timing with an old timing light.

Tom/Electronic Memory when it powers up theres a "sound step" noise squeal and this squealing noise. Is that the horizontal running off frequency?

I had it on. This time it didnt squeal and it settled around 220ma then slowly lowered to 190 then slowly moved to 200ma then it sounded like something came up and the meter rushed up to near 300ma. Turning the coil didnt really do much is seamed. Of course when it jumped up i turned it off
Reply With Quote
  #32  
Old 11-27-2018, 08:39 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
Squealing is usually the osc off frequency. Not sure my imagination can do much with"sound step" though.

Do you have an oscilloscope? If you do you can use that to adjust the osc with the output pulled. If not get video on the screen and some vertical deflection and adjust the H osc according to the procedure in the Sam's photofact for your chassis. A minute or so of ~250mA shouldn't kill the flyback, much longer is not advisable though.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
  #33  
Old 11-27-2018, 09:02 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
Quote:
Originally Posted by Electronic M View Post
Squealing is usually the osc off frequency. Not sure my imagination can do much with"sound step" though.

Do you have an oscilloscope? If you do you can use that to adjust the osc with the output pulled. If not get video on the screen and some vertical deflection and adjust the H osc according to the procedure in the Sam's photofact for your chassis. A minute or so of ~250mA shouldn't kill the flyback, much longer is not advisable though.
Yes I have a o scope. Sound step I mean like almost a quick step of different pitch squealing. Like playing EADG of a guitar then it stabilized. Last i powered it on the squeal went away. Im not getting anything on the screen or sound. Im gonna make sure all the tubes are socketd down
Reply With Quote
  #34  
Old 11-27-2018, 10:11 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
The wave on the 100ohm resistor to pin 2/6 of the h output tube is really "steep" compared to the waveform on the sams which has a really broad curve thing. im definitely turning the core and its not changing the wave form.
Reply With Quote
  #35  
Old 11-27-2018, 10:20 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
The wave form is much narrowed then the rather broad looking wave in the sams. Turning the slug has no effect on the wave form. Im looking at the sams thinking why that would be
Reply With Quote
Audiokarma
  #36  
Old 11-27-2018, 10:56 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
Since I my CTC-25 info went with my CTC-25 to its new owner I'm kind of flying blind here.

Which slug are you turning? If it is the linearity slug that will have no effect on the frequency and probably very limited effect if any on the H out grid drive waveform.
Are you adjusting the slug with a proper plastic hex adjustment tool? If you use a metal hex key for adjustment you will crack your slug (which will make it feel like it is turning when it is not) in short order.

The general procedure I go on for a rough osc adjustment is this: Connect scope to a composite video source (a VCR or DVD showing a blank screen is nice for this) and tune the scope to show 1-3 cycles of horizontal sync/video lines, count the number of divisions between leading edges of peaks, leave scope H/time settings exactly as they are from here on, connect scope to TVs horizontal osc test points adjust the horizontal osc trans top slug for the correct width of the waveform (make sure peaks are same distance apart as you measured with composite video) then if needed adjust the bottom slug for wave shape in the osc section (don't worry about output grid yet). Generally, I rough in the frequency and wave shape then follow sam's instructions when I have a picture on screen to optimize things. If after adjusting the osc the waveform at the grid of the output tube looks bad check the components between the osc and output.
The osc trans will be next to the H osc tube (usually a 6CG7) on the sweep PCB...There are two slugs in the osc transformer a top (usually freq) and a bottom (usually shape) and they may interact a bit...Some RCAs did a dirty trick and did not give a bottom access hole in the bottom of the board for the lower slug...Instead, to adjust it you had to have a plastic alignment tool that only had a 1/4" or less hex section on the end of the shaft and was narrower than the hex over the rest of the shaft. That tool made it possible to adjust both slugs separately from the top. You can still find those alignment tools for sale online.

One thing to watch out for on RCA per your explanation of the stepped freq behavior is bad PCB solder joints...The worst spots are on the H osc, H lin/efficiency coils, and the board ground to chassis ground joints, and tube sockets that all have a lot of mechanical stress on them. If they crack you will get weird intermittent behavior that makes no sense. I will often reflow them whenever I have weird symptoms. A 75W or higher gun or preferably soldering iron is best for the grounds...Everything else, use a more tame iron for.

That is all the wisdom I've got for tonight. I'm going to bed. Good luck.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
  #37  
Old 11-28-2018, 01:57 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
Quote:
Originally Posted by Electronic M View Post
Since I my CTC-25 info went with my CTC-25 to its new owner I'm kind of flying blind here.

Which slug are you turning? If it is the linearity slug that will have no effect on the frequency and probably very limited effect if any on the H out grid drive waveform.
Are you adjusting the slug with a proper plastic hex adjustment tool? If you use a metal hex key for adjustment you will crack your slug (which will make it feel like it is turning when it is not) in short order.

The general procedure I go on for a rough osc adjustment is this: Connect scope to a composite video source (a VCR or DVD showing a blank screen is nice for this) and tune the scope to show 1-3 cycles of horizontal sync/video lines, count the number of divisions between leading edges of peaks, leave scope H/time settings exactly as they are from here on, connect scope to TVs horizontal osc test points adjust the horizontal osc trans top slug for the correct width of the waveform (make sure peaks are same distance apart as you measured with composite video) then if needed adjust the bottom slug for wave shape in the osc section (don't worry about output grid yet). Generally, I rough in the frequency and wave shape then follow sam's instructions when I have a picture on screen to optimize things. If after adjusting the osc the waveform at the grid of the output tube looks bad check the components between the osc and output.
The osc trans will be next to the H osc tube (usually a 6CG7) on the sweep PCB...There are two slugs in the osc transformer a top (usually freq) and a bottom (usually shape) and they may interact a bit...Some RCAs did a dirty trick and did not give a bottom access hole in the bottom of the board for the lower slug...Instead, to adjust it you had to have a plastic alignment tool that only had a 1/4" or less hex section on the end of the shaft and was narrower than the hex over the rest of the shaft. That tool made it possible to adjust both slugs separately from the top. You can still find those alignment tools for sale online.

One thing to watch out for on RCA per your explanation of the stepped freq behavior is bad PCB solder joints...The worst spots are on the H osc, H lin/efficiency coils, and the board ground to chassis ground joints, and tube sockets that all have a lot of mechanical stress on them. If they crack you will get weird intermittent behavior that makes no sense. I will often reflow them whenever I have weird symptoms. A 75W or higher gun or preferably soldering iron is best for the grounds...Everything else, use a more tame iron for.

That is all the wisdom I've got for tonight. I'm going to bed. Good luck.

I was tunning the h efficiency coil so that makes sense why there was no change. I do not have a plastic hex. I have an "Ifixit" tool case with the proper size hex end but it is metal.

I dont have a vcr BUT i have a lot of old cartridge based nintendo and sega video game consoles I can use for a composite source. So youre saying to fire up the scope attatched to a blank composite source and then dial in the scope to get a wave form then keep the scope on those setting and attatch the scope to the tv and adjust the h slug to match the wave from a blank input setting from the composite signal of my choice?

I might end up doing some reflowing. I had audio and video before the chassis went on the bench. Now theres no sound or video. All I did was replace a few ecaps and re silicone the fly. Thank you for your help Tom.
Reply With Quote
  #38  
Old 11-28-2018, 02:34 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
Quote:
Originally Posted by ZenithNut View Post
I was tunning the h efficiency coil so that makes sense why there was no change. I do not have a plastic hex. I have an "Ifixit" tool case with the proper size hex end but it is metal.

I dont have a vcr BUT i have a lot of old cartridge based nintendo and sega video game consoles I can use for a composite source. So youre saying to fire up the scope attatched to a blank composite source and then dial in the scope to get a wave form then keep the scope on those setting and attatch the scope to the tv and adjust the h slug to match the wave from a blank input setting from the composite signal of my choice?

I might end up doing some reflowing. I had audio and video before the chassis went on the bench. Now theres no sound or video. All I did was replace a few ecaps and re silicone the fly. Thank you for your help Tom.
Definitely get a plastic alignment tool and stop using the metal one before you crack your slug... I've been there done that, and can say removing a crack slug without destroying the coil can be a royal pain in the butt... sourcing a new slug can be tricky too.

The only thing you will need to change on your scope is the vertical voltage scale. Composite video is about 1vpp and h osc waveforms in tube set are on the order of 50vpp...
How new your game system is can be important if you plan to use it as a H frequency reference. Older game systems used 240p rather than 525i. That change shifted the horizontal frequency a bit, and while most sets can sync to it I'm leery of using some random spec a programmer came up with because they were too cheap/reasource strapped to create a proper NTSC spec video source.

If you lost video and sound together you probably want to check tuner and IF systems. Wiggle tubes and if you get noise that stage and everything between it and the video detector diode are fine. In some cases the IF lead to the tuner will open or go intermittent... I have a CTC15 clone where the tuner and it's IF lead are permanently connected to the main chassis with soldered wire. The point the IF lead solders to the tuner has no strain relief so when I pull the chassis the center conductor of the IF lead tends to break off of it's tuner solder post... killing both picture and sound.

Do you have raster? If not check your boost voltage. Troubleshooting, adjustment and repair all get easier with the screen lightning.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
  #39  
Old 11-28-2018, 04:26 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
Quote:
Originally Posted by Electronic M View Post
Definitely get a plastic alignment tool and stop using the metal one before you crack your slug... I've been there done that, and can say removing a crack slug without destroying the coil can be a royal pain in the butt... sourcing a new slug can be tricky too.

The only thing you will need to change on your scope is the vertical voltage scale. Composite video is about 1vpp and h osc waveforms in tube set are on the order of 50vpp...
How new your game system is can be important if you plan to use it as a H frequency reference. Older game systems used 240p rather than 525i. That change shifted the horizontal frequency a bit, and while most sets can sync to it I'm leery of using some random spec a programmer came up with because they were too cheap/reasource strapped to create a proper NTSC spec video source.

If you lost video and sound together you probably want to check tuner and IF systems. Wiggle tubes and if you get noise that stage and everything between it and the video detector diode are fine. In some cases the IF lead to the tuner will open or go intermittent... I have a CTC15 clone where the tuner and it's IF lead are permanently connected to the main chassis with soldered wire. The point the IF lead solders to the tuner has no strain relief so when I pull the chassis the center conductor of the IF lead tends to break off of it's tuner solder post... killing both picture and sound.

Do you have raster? If not check your boost voltage. Troubleshooting, adjustment and repair all get easier with the screen lightning.

Now that i think of it i dont have the antenna or uhf/vhf cables connected. Ill hook the tunner up as needed. I ended up using my super nintendo to get a nice wave form 9 divisions wide and 30 high. The sams says theres a waveform off pin 8 of the h osc tube. It was thinner and super high/long, not sure what exact words to use to describe it. Ill get a plastic hex as suggested. Since I wont be tunning the slugs with a metal hex ill do as much more as i can in this set then im gonna get (a much simpler) zenith bw tv going chassis 17T20.
Reply With Quote
  #40  
Old 11-28-2018, 04:53 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
There's little point in doing the scope work till you have the correct adjustment tool. Another good reason to not use a metal adjustment tool is that the magnetic properties of the adjustment tool have the same effect as the magnetic properties of the slug.... simply inserting a metal tool or removing it has the same effect.on the circuit as turning the slug some amount...so if you get an adjustment perfect with the metal tool then as soon as you removed the tool the adjustment is thrown off of that perfect setting.

The "height" ie signal amplitude and wave shape of composite video and h osc waveforms are going to be radically different... the goal is to compare the synch frequency (width between pulses) and h osc frequency to allow calibration of osc frequency to a known reference.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
Audiokarma
  #41  
Old 11-29-2018, 02:57 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
Quote:
Originally Posted by Electronic M View Post
There's little point in doing the scope work till you have the correct adjustment tool. Another good reason to not use a metal adjustment tool is that the magnetic properties of the adjustment tool have the same effect as the magnetic properties of the slug.... simply inserting a metal tool or removing it has the same effect.on the circuit as turning the slug some amount...so if you get an adjustment perfect with the metal tool then as soon as you removed the tool the adjustment is thrown off of that perfect setting.

The "height" ie signal amplitude and wave shape of composite video and h osc waveforms are going to be radically different... the goal is to compare the synch frequency (width between pulses) and h osc frequency to allow calibration of osc frequency to a known reference.
So something ive been meaning to ask as Im having difficulty finding the answer in the sams. What would be the "normal" operating condition position for all the switchs? I had the yoke pulled back before it went on the bench and the red/blue/ green looked great as is with minimal smearing. I had a red blob centered. I know the norm/service/raster switch should be in normal but what about the color guns and all these other controls? Where should they be so i can get something on the screen?
Reply With Quote
  #42  
Old 11-29-2018, 04:51 PM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
The switch positions should be fairly obvious.. the potentiometer positions that you seem to be asking about vary with CRT health, signal conditions, and opperational health of the chassis.

Assuming you have the right HV voltage, focus voltage and the right boost voltage (if not focus on getting those right before expecting light on screen) then crank the brightness clockwise with contrast Midway and color fully counterclockwise and look for light...If none flip to service position on service switch. If still nothing then while watching the screen (in a mirror if needed) turn up one screen/G2 control till it gives light or you hit its mechanical limit...if you hit the limit reset to about where you started and try it on a different color screen. If still nothing after all screens tried look for a subbrightness control and crank that. If still nothing check cathode and geid voltages against the schematic.

Assuming you get light and have messed with G2 here's how to set G2 on a working set...turn brightness to min flip service switch feed set blank signal, turn red g2 for faint red line, then turn green g2 to make line yellow, then adjust blue to get white...if a color.is too weak turn up subbrightness or if none exists brightness and start again... that should make blacks black...if whites are funny colored adjust color drive controls.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
  #43  
Old 11-29-2018, 06:10 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
Quote:
Originally Posted by Electronic M View Post
The switch positions should be fairly obvious.. the potentiometer positions that you seem to be asking about vary with CRT health, signal conditions, and opperational health of the chassis.

Assuming you have the right HV voltage, focus voltage and the right boost voltage (if not focus on getting those right before expecting light on screen) then crank the brightness clockwise with contrast Midway and color fully counterclockwise and look for light...If none flip to service position on service switch. If still nothing then while watching the screen (in a mirror if needed) turn up one screen/G2 control till it gives light or you hit its mechanical limit...if you hit the limit reset to about where you started and try it on a different color screen. If still nothing after all screens tried look for a subbrightness control and crank that. If still nothing check cathode and geid voltages against the schematic.

Assuming you get light and have messed with G2 here's how to set G2 on a working set...turn brightness to min flip service switch feed set blank signal, turn red g2 for faint red line, then turn green g2 to make line yellow, then adjust blue to get white...if a color.is too weak turn up subbrightness or if none exists brightness and start again... that should make blacks black...if whites are funny colored adjust color drive controls.
I hooked up the rf output rca jack to the tuner and fired it up. Same thing. So I turned it off and took off the top of the fly cage and turned it on. Visible corona cloud around the cup of the fly back and the g output cathode current leveled at 200ma. I then saw a little bright flash in the 2av2. So i shut it off. So theres definitely hv. But why would the cathode current jump with the hv rectifier connected? I did have to resolder the 2nd anode connection on the base of the hv rectifier. I know the crt isnt shorted
Reply With Quote
  #44  
Old 11-29-2018, 06:32 PM
ZenithNut ZenithNut is offline
VideoKarma Member
 
Join Date: Jul 2018
Location: Humboldt County, California
Posts: 78
I put the 2av2 set up correctly in my tube tester and all it does is peg the meter in the good range
Reply With Quote
  #45  
Old 11-29-2018, 09:24 PM
old_coot88 old_coot88 is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 2,541
Quote:
Originally Posted by Electronic M View Post
...if a color is too weak turn up subbrightness or if none exists brightness and start again...
Doesn't the '25 have a Kine Bias switch? If so, it might be dirty. Try cycling it a few times with a shot of cleaner.
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 12:43 PM.



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