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