Question about Sony KP-57HW40 57" Rear Projection Television
Unfortunately that unit has been a real pain among techs who change out the focus blocks only to later discover it's the tubes themselves.
Get throught he front grill, sounds like you've been there before if you've adjusted the HV on the block already. Take the rubber end of a screw driver and gently tap on each of the three necks of each CRT - - from what you've said I'd suspect you'll see all kinds of flicker when you get to the red crt... Bad guns in the tube requires replacing the crt, but not really worth the cost at this age...
Hope this helps!
William Rayburn, CET
Posted on Oct 05, 2009
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Posted on Jan 02, 2017
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You have a problem with the three factors, and they are screen voltage, focus voltage, and control (focus 2) voltage. Basically these voltages have to be adjusted since the components in this section have aged some. These controls are usually located in the television on the IHVT (Integrated High Voltage Transformer) or as it is also called the flyback transformer. these controls must be adjusted together, along with the color controls. Here is how the adjustment is done (You will need a schematic diagram, a DC volt meter, and a color bar generator to do these measurments):
1) turn color and tint fully counter clockwise until you have a black and white picture.
2) connect the color bar generator to the TV (ch 3) and turn it on, you should see bars in various shades of gray
3) adjust as best as possible the color and tint controls to obtain the color bars on the screen Red Green Blue.
4) measure the voltages on the focus, screen and control grids of the CRT and match them to the schematic digram measurements.
5) adjust the focus screen and control grids to match the ones on the schematic diagram
6) once this is done then you adjust the color controls once again to obtain the red green and blue bars on the TV screen.
This should help if the CRT (picture tube) electron guns are still good and if the flyback transformer voltage supply is working.
However if you do not have a background in electronics please take the TV to a shop for repairs.
I hope this helps,
Oct 16, 2007 | Sony KV-20M20 20" TV
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