Picture is very dark, all color signals are there, pix and sound are fine, tried adjusting brightness, some improvement but still not good pix, i hear a cap whistling faintly but cannot locate, im working without a schematic, so tracing luminance signal is a bit hairy, just wondering if anyone has ran across this problem and can offer a quick fix.
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Re: low or no luminance
Projection TV tubes have a liquid coolant that is used to keep them from overheating. After many years the coolant in the blue and green tubes will become cloudy and cause the screen to look dull, red/orange, dark, etc. You may even see halos around images.
What you will need to do is replace the coolant and clean the crt. You can get a repair kit from www.TvRepairKits.com that includes replacement coolant, photos. instructions, etc.
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Check 'brightness' and 'contrast' settings in (usually) 'picture' menu. Use a recording (DVD etc.) of a dark scene to adjust the picture. My TV (not Sharp) has several pre-programmed picture settings. If yours has that, maybe one of them will be good. Otherwise, use manual settings.
It sounds like you are missing the luminance drive to the CRT board or the voltage that is provided to amplify the signal. The reason you get a good on screen display is that it is it is fed from aseperate circuit and you get some images because the chrominance signal is still being supplied. The video signal is made up of these two component- luminance and chroma. You usually need an oscilliscope to troubleshoot.
This is from the MANUAL www.westinghousedigital.com/pdf/197_User_Manual.pdf
A-1 Settings Use the Settings sub-menu options to manually adjust the display quality. Use the ◄/► keys to adjust the option level. Adjust the luminance level. Adjust the brightness to darkness ratio. Adjust the balance of the red, green, and blue colors in the display. Adjust the color intensity. Adjust the sharpness or softness of the display. Adjust the brightness level of the screen backlight.
AND this is from the troubleshooting procedures in the manual
Wrong, abnormal or missing colors
・ If any colors (red, green or blue) are missing, check the video cable to make sure it is securely connected. Loose or broken pins in the cable connector could cause an improper connection. ・ Press and select Picture | Settings to adjust the Hue and Saturation settings. You can also select Picture | Advanced to adjust the Color Temperature settings. ・Connect the TV to another computer and check if the problem is with the computer screen.
Other than that there is no mention of color adjustment
You can make several adjustments to improve your images such as lightening dark areas, changing the exposure, sharpening blurred edges, and changing the brightness and contrast.
Exposure adjusts the overall intensity of light in an image.
Adaptive Lighting improves only the dark areas in an image without affecting the bright areas.
Brightness adjusts the amount of light in colors ranging from light to dark.
Contrast adjusts the difference in brightness between light and dark areas of an image.
Sharpness helps define edges and the smoothness of texture in an image. Use this tool to make a blurred image appear more focused.
Adjusting the image
Follow the steps below to make adjustments:
Click the View tab and select the image you want to edit by either clicking the image, or by clicking the small box at the bottom left corner of the image.
Figure 1: Select the image
Click the Edit tab and then click the Advanced tab.
On the Advanced tools tab, click Adjust Image .
Select an adjustment from the list on the left.
Figure 2: Adjusting the brightness
The Exposure adjustment is automatically applied when the Adjust Image tool opens. Eight variations of the image are displayed on the left. The current image is displayed in the center. Each image represents a different level of adjustment. When you move the pointer over any of the images on the left, a large version of the image is displayed. Use Preferences to turn this large image preview on or off and to set the timing for the display.
If you want to use a different adjustment tool, select Adaptive Lighting , Brightness , Contrast , or Sharpness from the list.
Select one of the images on the left.
Do one of the following:
Click Accept to accept all changes and exit from the Color Toolkit.
Click Cancel to discard all changes and exit from the Color Toolkit.
If you have finished modifying the image, do one of the following to save your changes:
Click Save to overwrite the original image.
Click Save As to save the modified image with a different name.
Adjustable Color Temp.
The Adjustable Color Temperature feature lets you adjust the color balance on your TV, depending on the type of light in the room, such as direct sunlight or artificial lighting.
On your remote control there should be a button that lets you change the picture mode, IE. Rich, Personnal, Cinema, Sport etc...
The picture is very dark
it is mostly due to
1 power supply output is low.
2 voltage on crt g2 pin is low.
3 video output supply is low.
4 some components in luminance section might be defective or loose.
5 finally crt getting weak is set is old.
It is hooked up to Direct TV. When I change the channel on the TV to another input it looks fine but without a picture.
as you do not see tint in another channel means your color section is ok
it is due to video or luminance section.
On the inside of the TV, on the flyback transformer there should be two controls. Turn the one that says "screen" very slowly clockwise while looking at the pix. The pix should get brighter as you turn it up- if you go to far you will see lines in the pix or the TV may shutdown.
Open up the front of the set and find the screen controls and perform a grey scal alighnment by adjusting the red , blue , and green screen controls but be carefull and make sure you adjust them evenly or the picture will not look right. Good Luck