Question about Toshiba 50H72 50" Rear Projection Television

Open Question

As I understand, there are 3 colors, red/blue & green, to control and adjust. Both red & blue are working OK. Only green is giving problem. The problem is not at the whole screen. It has a upword wave, about 2", at the mid bottum. It gradualy reduce as you up and disapear at the middle of screen. My e.mail is wasimaqureshi@yahoo.com Thanks for your help.

Posted by on

Ad

5 Suggested Answers

Anonymous

  • 18 Answers

SOURCE: Green Convergence problem

O.K. This is a CRT Projection TV see http://www.tacp.toshiba.com/televisions/product.asp?model=50H82 The Manual is available from http://www.tacp.toshiba.com/tacpassets-images/models/50H82/docs/50H82_om_e.pdf , and this describes the Manual Convergence process, I doubt this will help, but it's step #1. The problem you are describing sound to me like a deflection problem. The electron beam in the green projection 'tube' (a super bright CRT) is probably not being controlled correctly. This can be caused by several things, from least likely to most :) I do not recommend that someone untrained in electronics attempt to service a CRT based television due to the potential for extreme shock or electrocution. That caveat said, here are the possibilities. #1 Physical Trauma: The TV has been shifted moved or bumped hard, and one or more of the fixed permanent magnets used to help convergence has come loose, or the CRT projection tube was damaged. I don't think these TVs use convergence magnets anymore, but it's possible. The green CRT tube failing would be more likely if all four corners were affected, but I've seen a failing CRT affect a single corner/edge before. I believe that this model has projection tubes that are separate from the colored filters, so swapping the tubes around may be possible. I do not have a service manual for this set, and this may be a hazardous operation due to high voltages. #2 Stray magnetic field: Someone dropped a magnet into the TV, and it landed close enough to the green tube to effect it only, or perhaps some other piece of equipment is effecting JUST the Green CRT (clock radio, speaker, badly designed wall wart, etc.). Removing the offending magnetic field may cure the problem. Perhaps the offending magnetic field has been removed, but it's presence is still felt. Try using the degauss function built into the TV set (I can't find one in the manual, but it may be present). You may want to try using a degaussing coil, and see if that helps the problem. Just be careful not to get the coil too close to the base of the projector tubes. #3 Deflection drive electronics: A CRT works by using an electron beam to excite fluorescent compounds on the face of the CRT. To move the electron beam about, a process called deflection is employed. Magnetic coils (the choke) are used to steer the electron beam up, down, left or right. These coils are driven by transistors, and as one fails, you will get an image that starts collapsing in the affected section. On a standard CRT TV, that would mean the entire image is affected, but a CRT projection display uses separate red, green, and blue CRT projection tubes to build the image, so you have three times the deflection, three times the possible transistor failures, and in your case, the odd result of just the green part of the image displaying incorrectly. This problem will probably require a service call, and a electronic board swap, but the problem could be the choke (the magnetic coils) on the green CRT projection tube. Swapping the green tube for another tube could prove if it's the tube or if the deflection electronics that are going out. Again, my feeling is that this is a deflection issue requiring a board swap (I doubt anyone actually does component level repair anymore) Sorry, I don't have a better answer, peace. Paul.

Posted on Jan 13, 2007

Ad
MikeNJ1964

Mike Longo

  • 398 Answers

SOURCE: color convergence

Usually, what happens in those sets is that one of the STK output IC's shorts out.  Each IC has 3 separate channels, and one of the channels shorts out, which sends B+ or B- to the convergence coil.  This burns out the low-value resistor associated with that channel.  If the bad IC is replaced but the resistor is not, that channel will continue to not work.  Look for 3 large resistors right next to each IC.  These resistors are 1 or 2 watt resistors, have a value of about 1.8 ohms and sometimes are under the heat sink fins that the IC is bolted to.  Measure all 6 resistors with an ohm meter and you will probably find one of them is open.  Replace that resistor and your colors should return to their normal positions.

Posted on Oct 12, 2007

Ad
eagle338

eagle338

  • 4889 Answers

SOURCE: Red color convergence on Toshiba 57H81

Often convergence issues do not require the entire board to be replaced. You can resolve it by replacing the convergence ICs. The part in question is STK392-110. You will need two of them and they cost around 10$ each. But replacing them is a pretty complicated procedure and I would not suggest it to someone without prior experience. A service manual should get you started in the right direction if you are planning to do this yourself.
https://www.completeservicemanuals.com/toshiba/crt-projection-television/57h81-service-manual/prod_1128.html

PS
: Disconnect from the power supply before you start the repair. Also read the legend, the hv circuits are denoted by a special symbol, so you will know what you shouldn't touch.

You may also need to replace the nearby resistors that may have popped the IC in the first place. Read the service manual for further details.

Good luck,
Sai.

Posted on Apr 01, 2009

Slinteriors

Sonny Berry

  • 8617 Answers

SOURCE: colors out of focus- like a really bad 3-d movie

the convergence issue can be usually repaired by replaceing both of the STK392-110 Convergence amps and the six 1.2 ohm 2 watt resistors. You can get replacement parts at the following link with instructions on how to replace the ICs.
http://servicemanuals.vstore.ca/

Posted on May 22, 2009

SD Tech

SD Tech

  • 14553 Answers

SOURCE: the convergence is off. When I try to use touch

Ok, we go to solution of your problem===The pico fuses are green and on the main power board--have you removed the back and looked inside--most of these sets have the two STK-392-110 on the main board to the right-they are usually on the left edge of this board on two very large metal heat sinks--chips are about 2 1/2 inch wide X 1 1/2 inch tall--is this how your set looks inside? they will have the number printed on the black face of each chip in white--The fluke meter will allow you to check all the grey protect resistors--most are 1.8 ohm and the pico fuses will be near the edge of the board to the left----All I expect from you for help is a vote here--if you remove the back do you see the chips?

Posted on Sep 19, 2009

Testimonial: "I am delighted with this site and the people that are accociated with it. It amazes me, the level of expertise and the willingness to help someone. "

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

The DP26649 model TV has three inputs; video one (which is fine and has all color and everything), video 2 (if you plug them in certain ones the best i can get is full sound and all but its black and...


OK, here is the breakdown on whet you are doing wrong.

Video 1 - Composite -
Video - Yellow
White - Audio In - Right
Red - Audio in - Left

Video 2 - Components - HD - RGB = Red, Green, Blue
Video -
Red - Red Colors
Green - Green Colors
Blue - Blue Colors
White - Audio In - Right
Red - Audio in - Left

Your GameCube will only work on Video 1, unless you buy an HD (Component cable). You will need to buy HD cables for your device connected to Video 1 to work on video 2. I will assume it is a DVD player. This is a high definition cable to produce a better picture. Let me know if you do not completely understand

In case of a problem or clarification or my solution was insufficient, don't hesitate to post me a reply.

If you are satisfied, rate my solution with the "thumbs" or (even better) add a testimonial.

Jun 06, 2011 | Televison & Video

2 Answers

PT50LC14 Color problem with color too much yellow and green no white or blues can not correct is this the lamp again im on why does it seem that I end up replacing the lamp every year (on number 3 now)....


ok,,your problem is not on the lamp itself.,the problem is on your screen controller.the controller is connected on the plyback you can adjust the screen intensity of the red,green,blue cathode..on your screen adjustment.

May 17, 2010 | Panasonic PT-50LC14 50" Rear Projection...

1 Answer

The pictures are all blurry and all three colors show up on the screen volume and everything else is ok what do i do


you can adjust your screen focus located at the main controll pannel it is labelled as focus adjustment..if this not work replace the CRT socket of the 3 cathodes the red,green and blue

May 17, 2010 | Philips Magnavox 51MP392H Rear Projection...

1 Answer

Hitachi 53UWX10BA dynamic convergence works but blue is blurry


I know this set very well---you are saying convergence adjusts ok everywhere? If you understand that the blue is usually de-focused a little----there are only two ways to adjust the focus of each tube-----

1.) Behind the front speaker grill there is an inspection plate---with it removed you will see a small black plastic block with 6 controls on it; it is the MASTER SCREEN/ FOCUS BLOCK

2.) THREE of the controls left to right are Screen controls(red, green and blue) and the other 3 are FOCUS--IT IS ALL black and you need to look close to identify which is focus and which is screen---you are looking for the BLUE focus control(one of the 6)

3.) With the convergence grid on screen cover the RED and GREEN lens in the set and try to adjust the focus of the blue(I presume you know how to put the set into the Convergence mode?

4.) The only other way to adjust the Blue focus is from the back of the set---with the Red and Green lens covered up place a blanket over the top of the set that covers the whole screen--from the back of the set you will note that all three of the black focal lens have a wing nut---with the convergence grid up and only blue lines present(Green and Red lens covered with a cloth) look from behind the set at the grid---loosen the wing nut on the blue lens and slowly slide the lens left or right until the blue has the best focus possible----if it will not adjust with the focal lens or the front focus control you have a circuit problem.

I do this here for free and if this information helps you take a minute and give me a vote here. If you have any questions or need advice reply to this posting here and I will assist you.

SD TECH

Sep 14, 2009 | Hitachi 53UWX10B 53" Rear Projection...

1 Answer

I was just given this t.v because friends couldn't figure out what is wrong with itl. The colors don't line up right,looks kinda blurry depending on the lighting of the program being watched. How do i fix...


According to the manual:
1) go to the "TV Main Menu"
2) Select "Screen"
3) Select Adjust Projection TV (obviously only if a projection TV).
This then allows you to adjust the TV's 3-colors. Selecting GREEN CENTERING brings up a control panel that lets you center the green projection tube on the screen. Selecting RED CONVERGENCE or BLUE CONVERGENCE lets you align the Red & Blue projector tubes. Centre the green projector tube 1st. Then adjust the red & blue until the test pattern on the TV screen appers white.
Good Luck!

Jun 08, 2009 | Proscan PS50700 50" Rear Projection...

2 Answers

Picture calibration settings for 42lg70


Picture Menu
Picture Mode: Expert1
*Backlight: 16
*Contrast: 83
*Brightness: 53
Sharpness: 50
*Color: 55
*Tint: 0
Expert Control
  • Fresh Contrast: Off
  • Noise Reduction: Medium
  • Gamma: Medium
  • Black Level: Low
  • Real Cinema: On
  • TruMotion: Low
  • Color Standard: HD (N/A w/HDMI)
  • White Balance: Warm
  • **Method: 10-Point IRE
    • 10 IRE
      • **Red: 1
      • **Green: 2
      • **Blue: -16
    • 20 IRE
      • **Red: -6
      • **Green: 0
      • **Blue: -7
    • 30 IRE
      • **Red: -5
      • **Green: 0
      • **Blue: -4
    • 40 IRE
      • **Red: -8
      • **Green: 0
      • **Blue: -4
    • 50 IRE
      • **Red: -4
      • **Green: 4
      • **Blue: -4
    • 60 IRE
      • **Red: -6
      • **Green: 6
      • **Blue: -5
    • 70 IRE
      • **Red: -8
      • **Green: 3
      • **Blue: -10
    • 80 IRE
      • **Red: -8
      • **Green: 7
      • **Blue: -16
    • 90 IRE
      • **Red: -9
      • **Green: 5
      • **Blue: -18
    • 100 IRE
      • **Red: -10
      • **Green: 4
      • **Blue: -9
Color Management System
  • Red Color: 0
  • Red Tint: 0
  • Green Color: 0
  • Green Tint: -15
  • Blue Color: 0
  • Blue Tint: 11
  • Yellow Color: 15
  • Yellow Tint: 2
  • Cyan Color: -15
  • Cyan Tint: 0
  • Magenta Color: 0
  • Magenta Tint: -1

lg70 nice tv excellent processor just to bad there is no intensity control on color management oh well still better than what the three s are pushing block out the hype lg will be number 1 in a few years haters are starting to come around and well leds coming,

p.s. i dont work for lg just tired of losers bashing stuff because they dont own it.
im isf certified those settings are right on the money straighter than a ruler

Oct 05, 2008 | Televison & Video

1 Answer

G2 alignments?


Hello YankeeTwidgt,

Here we go you will need a schematic diagram (You may already have one but I thought I would mention it ), an oscilloscope, a TV signal generator (NTSC color bar, RGB purity screens, and pattern screen), and a voltmeter (I would prefer you have a VTVM, but a digital meter with high impedance (>=10M) will be ok).

First turn all of the color and tint controls completely down (This includes the main color and tint and the pre-amp color controls if you have access to them).

Then turn the RGB pots fully counterclockwise.

Once this is done connect the signal generator set to channel 3, and set to the specifications on the schematic, use the color bars, what you should see at this point are bars of various shades of gray.

Then turn the generator to the purity setting and set the pattern to red.

Once this is done your screen should be dark or dark red, gradually adjust the R pot until the screen is pure red and the voltages, and signals match what is seen in the schematic (mark this point on the pot and the return the pot to fully counterclockwise).

Do the same for the Blue and Green Controls (Blue first and then Green).

Once all of the pots are marked and turned to counterclockwise, set the pattern to gray purity, and turn the pots back up to their marked positions, the screen should be gray. switch to color bars and the screen should have the proper colors.

This is a course adjustment, and you will have to do a fine adjustment using the schematic, and the test tools, but this will put you way into the ball park.

The reason these pots are not talked about in gray scale adjustments is because they usually don't have to be touched. That's why it is important to get them back to specification using the voltmeter and oscilloscope to set the signals up properly.


I wish you success,

Shuttle83


Jul 27, 2008 | Philips 51PW9303 51" Rear Projection...

1 Answer

Philips 50P8341 50 in. Rear Projection Television most of the color is red


Usually if you remove the speaker grill in front there is a convergence panel that can be carefully removed. If you look inside you should see a small rectangular block with six controls. They are labelled focus and screen, and red, blue and green. Adjust only the screen controls very carefully and slowly. I would recommend reducing the red slightly brfore raising the green and then blue until the picture looks acceptable. Be sure to center the on screen controls before starting.

Nov 18, 2007 | Philips 50P8341 50" Rear Projection...

1 Answer

Rear Projection Tv Problem! black and white... Please help


go into menu turn color off see if you have a black and white picture if not adjust red,green, and blue screen drive on controls in back of tv you have red, green, blue it will have focus /screen controls cover each tube do one at a time blue focus and screen drive adjust to clear blue picture do all 3 tubes, then adjust them to where you have a black&white picture once this is done turn color controll back on.Thank You for using FixYa and Have a Nice Day.

Nov 11, 2007 | Toshiba 50H72 50" Rear Projection...

1 Answer

Sony kp51hw40


did you adjust the green screen control .

Oct 01, 2007 | Sony KP-51HW40 51" Rear Projection...

Not finding what you are looking for?
Toshiba 50H72 50" Rear Projection Television Logo

Related Topics:

136 people viewed this question

Ask a Question

Usually answered in minutes!

Top Toshiba Televison & Video Experts

The Knight
The Knight

Level 3 Expert

76237 Answers

matt martin
matt martin

Level 3 Expert

1257 Answers

Cindy Wells

Level 3 Expert

6073 Answers

Are you a Toshiba Televison and Video Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...