Trinitron KV-32XBR35 Picture Goes Black, Sound Fine

[JPSanMo]

I am having issues with my Trinitron KV-32XBR35. When I turn it on, the picture comes on and then suddenly turns off after a little bit. Other times, the picture does not come on at all. However, the sound works perfectly.

Thumping on the side of the TV will cause the picture to come on momentarily. It used to stay on for a fairly long time after a thump, but now it is lasting shorter, sometimes only staying on for a second before going black again.

I am assuming it is something to do with the power supply to the picture tube and not the tube itself since the picture is perfect when it is on. Another idea I got from some posts Ive seen on the boards is that it may be overheating or have a faulty sensor that thinks it is.

Does anyone have any suggestions as to what the problem is?

Is this TV worth salvaging? What do you think it would cost to repair? Could I do it myself? I have a soldering iron and basic electronics understanding & skills.

I already bought a replacement, but am wondering how much time/effort I should sink into repairing this one. Should I just sell it? If so, for how much?

Any help is appreciated . . . Thanks!

[radiotvnut]

It most likely has bad solder connections in the horizontal sweep circuit. Re-solder the horizontal drive transformer, the horizontal output transistor, and the flyback transformer, and everything in between. The flyback transformer is the large transformer with the big red wire coming out the top. The horizontal output transistor is a large transistor that is fastened to a metal heatsink close to the flyback transformer. The horizontal driver transformer is a small transformer with one terminal connected to the "base" terminal of the horizontal output transistor. You could also have bad solder connections in the vertical output and power supply circuits. I wouldn't use it until I resoldered the horizontal output circuit because loose connecions here will eventually cause the horizontal output transistor to short, which will burn up parts in the power supply.

[kx250rider]

On that chassis, there are 3 or 4 STR-type IC regulators (on heat sinks, lined up appx in the center of the main board from the front to the rear), and those are 98% surely causing that problem due to cracked solder joints. I've fixed literally hundreds of those. on the bottom of the board, find the plastic frame reinforcement that runs from front to back, and you will see those bad connections. Resolder all of the pins from those regulator ICs. And Radiotvnut is also correct, in that the horizontal drive transformer gets bad connections. Follow the Base leg of the horizontal output transistor to the driver transistor and transformer, and solder the transformer legs.

Charles