My sony tv model no.kv-32fs100 screen goes black sound still on
If your TVs sound is Ok, and there is no picture means there is some fault in the horizontal output section inside the circuit bord of your tv. No Extra High Tension Voltages are generated in it. It may be due to Horizontal Output Transformer, usually say as [LOT], or its drive circuit, or line drive transformer failure. You can check if [EHT] that is Extra High Tension Voltage is genrating inside your TV or not.
Place your forearm parellel to the outer surcace of the picture tube, at about 2cm apart from it, and switch on your TV. If there is EHT geterated inside, the hairs of your forearm will be attracted towards the surface of the picture tube, and you can feel it. If it is not, there will be no attraction.
 If it is:- there is no screen voltage is coming to your picture tube. In most of Sony TVs the screen voltage is coming from one point in the printed circuit board, and its adjustment control is placed on the base card of the picture tube. Focus votage and screen voltages can be adjusted.
 If it isn't:- Your TVs LOT mentioned above has got damaged. LOT damage is is a general case in all TVs. Some times the driver transistor which drives the LOT also may also get damaged.
You just unplug your TV from wall socket, and open its back cover without damaging anything. Point out the horizontal drive transistor, usually can be seen very near to the LOT, screwed into a heatsink metal. Without touching any inside part, power on your TV. Wait for 2 minutes or so. Just power off and unplug it from the wall socket, and touch with your bare had on the transistor heatsink. If LOT is shorted, the transistor will be very hot during this time, and an "Ishhhh" sound also will be heard. If you have sufficient equipments, desolder and take out the horizontal output transistor mentioned above, and check it for collector to base leak. If it is leaky replacing it with same type and number will solve the problem. Anyway it should be replaced along with LOT replacement. Therefore just do it first. If the replaced one also overheats, surely LOT is damaged and it should alo be replaced with same type and number. If there is no heat in the transitor and if no hissing sound is heard from the LOT side, check for its [LOTs] supply voltage. It shoud be around 135 to 140VDC in 32" Sony sets. If there is no voltage, just track the circut print for any crack or have any series resistor failure.
If there is supply voltage to LOT and still it seems not working, come towards the Line Drive Transformer. It is a small transformer can be seen on the circuit board diretly soldered to it. If its winding gets opend, there will be no frequency [15625Hz] to drive the Horizontal Output Transistor. For all these checks you must have a multimeter and a soldering iron in hand.
Please remember how the TV was shut down. If it is during on working, and a sudden faulure it was, surely LOT is faulty. There is no doubt about it. Anyway take precautions before opening the back cover. Keep children away from you and let an adult beside you too. As much as 27KVDC [27,000VDC] points are there inside your tv. It is dangerous to touch. You can see that voltage wire, which comes from the LOT, and connected to the top side of the picture tube, seems to be sticked with a rubber boot to it. Never go nearby its side any part of your body.
you must have some skill, causiousness and more patience to do this work. Otherwise get help of any experience technicians for this job.
If you feels any difficulty; please inform to Fixya, and they will give me alerts. I'm here thousands of miles away from you and trying to solve your problem by understanding from some words of yours you remember. Anyway wish you sucess. Take care.
Oct 21, 2010 |
Sony FD Trinitron WEGA KV-32FS100 32" TV