Sony KV-29C5D CRT TV Repair

I found a cheap Sony KV-29C5D 29" Trinitron TV near my location. It was pretty dirty, but worked when I tested it at the previous owners house. After bringing it home it suddently stopped working after about 10 minutes of use and did not power on anymore. This is a small repair summary. Perhaps it helps other people fixing their unit in the future.

Here is the service manual for this TV (pulled from the Internet Archive): KV29C5_SONY_SERVICE_MANUAL.pdf

Disclaimer: CRT TVs operate at really high voltages (~25 KV) and can hurt or even kill you (even when they are not powered on). If you are not sure what you are doing, please do not try any repair attempts and ask someone who has some experience.

I built a discharge tool (VDE screwdriver with mounted cable + alligator clips) and got some high voltage gloves for extra safety:

To discharge the tube, you need to connect the ground strap to the anode contact (under the anode cap). It is adviced to repeat the discharge a few times, because larger tubes can recharge again after some time:

The board was pretty dirty and I had to clean it up a bit with some isopropyl alcohol and a toothbrush:

There where about 7 solder joints that looked broken and needed some solder reflow:

After some more searching I found a capacitor that was leaking and could be the possible fault, because it was in the standby circuit of the TV. That would explain why the power went off, without any error blinking codes. I also replaced all other caps that were near the faulty one and checked all diodes and resistors if they where damaged from the leaking cap.

After replacing the caps the TV powers on again and it worked flawless for about 3 hours. Then it powered off again. I soldered some small wires to different parts of the board, to safely measure some voltages when the TV is powered on.

I was pretty sure the fault was still in the standby circuit, because it had the same symptoms as before. The only remaining component that could be causing this issue was a TOP209P PWM switch that was right next to the leaking cap that was replaced earlier. Luckily there was still an Ebay seller in France that had these in stock for cheap. After replacing it the TV powered on again :-)

Now its time to do some calibration of the geometry and colors in the service menu: The geometry was mostly ok, but the image was shifted a bit too far out the edges horizontally and vertically.

The colors also seemed vibrant, so i didn't touch these settings much. I don't know how the picture of this TV looked when it was new, but overall it looks really nice. I guess maybe the tube has not a lot of usage hours on it.

After an evening of gaming with my kids, we confirmed that it is fixed now :-D

Here you can see the glowing cathode heater (filament).
I pushed the colors a bit on this picture so you can see it better:

And here is a picture of the aperture grille sub-pixel layout from this TV: