*solved* K7000 no colors part 2

DuffCon

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Have another k7000, no colors. Very similar image to this thread I did a while back:


Basically as you can see, we have deflection and image, just no colors. Chassis is fully rebuilt; caps, reflow, bad areas, etc. tried IC1 and IC2. No help. If I short a neck transistor, we get colors, so I assume everything is fine there

The previous threads issue was corroded input headers causing resistance on the RGB signal. This seems so similar, but the header on this chassis is fine.

Any ideas?
 

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Interesting; same procedure as the neck board? (Connect center leg to ground)
 
Figured it out. Shorting q1 did nothing, as well as swapping it out. Looking at the input voltages it was a bit high, but looking at the output on pins 17,19, &21 I noticed that they were really high like 6 volts, when the manual says 1.7 for each color.

The manual states that brightness is varied by the output voltages on these pins via input from pin 14, which was also very high. Measuring pin14 while turning the black level pot, I noticed it was either one of two high values, like 3.6 or 7 instead of a range. So then I looked closer at the pot itself:


IMG_3036.jpeg

Replaced and we are good!


IMG_3045.jpeg
 
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