Crt television tube

How long u have this RCA analoge tv?Around 10 years or more and used it like about 5 or 6 hrs everydays?Yes,than ur tv it is losing CRT tube radiation cohetion.As times go bye years in years out the tv CRT-(tv tube) radiation will slowly dying out,Tv actual pictures will lost some of it luster and it brightnesses to the tv auctual pictures.Brightnesses of CRT tube will get darker and darker until the tv actual pictures barely it is watchable anymore.Contrast,Brightness and Colors adjusting more will help some.But u have to take this tv aparts and take a Flat scerw driver turn up a little bit more of the tv HV-(high voltage) SCREEN button on the FBT-(flyback transformer) to make any big differences of the CRT tube brightnesses.The FBT-(flyback tranformer) is the big block of plastic with a red wire with a black cap hook up to the tv CRT-(tv tube).This adjustment on of the FBT,HV-SCREEN button will help the tv CRT-(tv tube) last another year or two.

You can replace the CRT ( TUBE) which has the HV wire installed in it. You can get replacement CRTs from www.tvrepairworld.com

is hv RGB circuit defective, needs to be repaired or CRT Tube is end of life.

Turn it off u leave on to long ur CRT Tube will dies soner.Resolder the FBT,the flyback transformer, the big block of plastic with a red wire with a cap hook to the and the transistor beside it.This transformer is the HV to the CRT to get power.

The anode lead comes out of the HV transformer, unplug the convergence plug for the tube you are doing, also unplug the yoke plug, remove black ground leads from under-side of that tube, then remove the 4 screws from the brace of the tube(crt), do not remove the screws that hold the black optic lens just yet, make sure all leads are disconnected and ready to remove crt from the cradle. Note the position of the crt before you take it out, the blue if you notice faces reverse of the R+G. such as the expansion chamber vent. Look for the drain plug, it removes CCW 1/2 turn. empty fluid into a container, then you can dismantle the lens and clean the face of the tube with alcohol and you cannot leave a speck of anything in there, it will show up in the picture. re-assembly is just the reverse, just make sure you put the exact amount of fluid back in and do not over tighten anything but secure. After you install the tube you will have to do a complete convergence alignment. This is not a procedure a novice should attempt. I do admire you willingness to attempt it, but please don't. Contact a SVC co. you won't regret it. Hope this helped in your decision.

Ed did you change the yokes when you put the DPTV series CRT into the PTV chassis? If not its most likely the vertical output or the Horizontal output that got destroyed. If you changed the yoke its most likely the HV generator.
On the DPTV chassis that should shutdown the vertical deflection which would leave audio working worse case scenario would also be the HV generator and Horizontal output.

I do not think the old tube rejuvenator will do much if the HV is arcing. The CRT it might leaking some coolant or some moisture from it is causing the arcing.
I would suggest to read the info from this website to re-seal it or replace the coolant.
Let me know if you need further assistance.

There is not that much high voltage on the projection tubes

Pull the red annode lead from the flyback transformer
Careful not to touch the end of the red lead

Brush the lead across the metal frame that the crt was housed in and that should disapate the hv
If you are not sure it is gone then stick it on the metal again

Remember the tv mus be unpluged befor you attempt this

Good luck

Leave set unplugged for a few hours = HV gone or discharge to CRT ground strap........................

Note: Part list.....257805 or ASTI 2078 xformer and
237470 horiz output xistor ( Do not use generic)
transistor must be first quality, no seconds ! !

I don't know your model of set very well. I will comment in general. I am assuming your set is using three CRT's for its projection system.

This is normaly a voltage regulation fault. As the CRT's pulls more current, the HV is dropping. A lower anode voltage means lower cathold current. What this does is lower the mass of the electron beam that is hitting the front phosphor in the tubes. Because of the lower electron mass, the deflection yoke has an easier time to pull or deflect the beam for scanning. And, thus the picture appears to increase in size.

If you look at low cost CRT TV sets, it is very common that the raster changes size a little with contrast and brightness change. This is because they use less quality of HV regulation.

Check the main power supply to see if it is stable with wide variation of picture contrast. Also, if you have an HV probe, check to see if the HV at the anodes of the CRT's is stable with changes in the picture contrast and brightness.

If the main power supply is stable, and the anode voltages are changing, then I would try the HV multiplier and flyback assembly.

This can also get a little complicated to troubleshoot. There is some regulation feedback reference from the HV drive that goes back to the HV generator circuit. There may be a fault in this area as well. Where this gets interesting to troubleshoot is where the horizontal scan drive is also the HV drive, as like most common CRT sets.

Some sets use scan compensation to also help for stability. They will control the gain of the scan amplifiers to help stabilize the scanning to make up the error difference in the HV regulation.

Jerry G.