"Joe Paulson" bravely wrote to "All" (07 Feb 04  02:04:38)
 --- on the heady topic of "TVcolor"

 JP> So I went down to the Goodwill auction and bought
 JP> a used 27" RCA TV for $10.
 JP>
 JP> Usually these electronics have some defects that I often can work
 JP> around.Opening it up,I found very little dust.Everything looked good
 JP> except the color.All white images had a yellow tint no matter how
 JP> I adjusted the COLOR,TINT,CONTRAST,GREEN-RED mix.

A yellow tint in the white areas means the blue gun current is too low.
If you recall, mixing only red and green gives yellow...


 JP> I tried the default
 JP> setup.All no help.Using the default setup,the faces of people had a
 JP> bluish tint.

It seems like the blue drive was turned up in the auto preset circuit
to compensate the low blue bias.

If it was my tv I would first try only tweaking the blue gun slightly.
In an older tv, I would put the tv in service mode so that only a
single line displays across the screen. If the colour was yellow that
would confirm the low blue bias and I would turn up the blue bias to
get a white line back. Normally that might take care of it but it
probably would need a proper colour setup to balance it correctly.


 JP> In the back,I could see some screwdriver color
 JP> adjustments but these had no effect.I could see controls for
 JP> SCREEN and FOCUS but I didn't have the required  small diameter tool
 JP> with a hex head .So I carefully drilled a lot of 1/8",then
1/4" holes
 JP> around the hole marked SCREEN and cut out the plastic.Then I used a
 JP> 9/64 " hex bit to rock the high wattage pot and saw no change.

Screen affects the overall brightness but your tv probably has an ABL
circuit which won't let you see the effect of adjusting the control.
The effect is often more noticable in the black areas than the white.


 JP> The board on the socket of the TV tube didn't have the red,green and
 JP> blue pots that I was familiar with.

The colour bias adjustment may only be accessible in a "service menu".
It requires a computer program and interface purchased from the mfgr.
RCA aka Thompson calls this their "chipper check"...
Most such adjustments were only in the "chipper check" service menu.
Kind of a rippoff for the DIY folk. Might it be worth taking the tv in
to a shop for a colour setup?


 JP> Now,I beginning to think that the magnet adjustments on the
 JP> neck of the TV tube may need tweaking.There are 3 sets and I was
 JP> waondering which one I should start with.I would watch to make white
 JP> images less yellow.    Any suggestions?

Don't fool with the magnets unless you have "a lot" of experience
doing convergence.

 Mike
 ****

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