Dear sir I am working with a Sony KVJ21MF model TV with a problem in Power Supply Section. No output from Power Supply. Only Noisy Occilation sound (around 50hz) from power supply. I replaced the SRT6707 but no improvement. Can anyone help me. Asif, Bangladesh

Measure the output voltages from the power supply section first. That will tell you which way to go forward.

I would start by testing the power supply section.

Your have problem in the power supply, since there is sound meaning the other section were working. Your Raster is missing or the horizontal and the vertical or your dont have high voltage to run the tube screen. Either the problem would be open Fuse or open resistor on the power supply or the Horizontal output stage damage.

hi,
Blinking led in sony tv is its self dioganising function. 7 blinks by it means the horizontal output voltage increased above 33k.
You have to check the power supply stage of you tv. Normally in sony tv dry soldering can happend in the power supply stage. It will lead to unregulated voltage output from the power supply. Resolder all the points in the power supply section it will solve your problem.
ok

Hello
Check the input fuse first. If it is blown, there will be some short inside the power regulator circuit. Usually Sony sets uses STR regulated power supply. You can see this STR, and Ic, screwed onto a heatsink. Replace it with a same type and number. Before replacing the STR, check the diodes used in that section for damage, mainlu zener diodes. They might get shorted along the blowing of the STR. Check that section throughly before resoldering the new STR.
If any further assistance you needs, get me through Fixya. Ok.

Hello
There are few models of Sony telivisions which uses transistors in vertical output section. It will be a matched pair of PNP and NPN transistors. According to Sony schematic which I have with me used 2SB6494(PNP) AND 2SD669A(NPN) as vertical outputs and 2SC2383 as vertical drive, 2SC1364 as vertical oscillator. Just try to get the orginal numbers or find its equivalents from data book. Ok.

Hello
Your TVs horizontal output stage is not working. That means, the line output side [LOT and related components], are inoperative. It may be due to some secondary missing voltages from the power supply section of your TV. There may be some open resistor, or short inside the Line Output Transformer [LOT] itself. Anyway that side is not working. Your TVs power supply regulator system has no trouble. It supplies the required voltage to the other sections. That is why you see the LED [Light Emitting Diode], fitted in front panel of your tv blinking for some time and shuts off. As soon as the TV is switched on, the power regulator system inside the tv will supply all the necessary secondary voltages to all sides. If at any section misses the required voltage, the system control Ic will detect it, and will try to rectify that. It is so programmed at the factory. If it can't do it, it will automatically shuts all the supplies from the power regulator system. It is a protection added by sony to all models of their Tvs.
You yourself cannot detect and repair this fault. Get the service of an experienced technician.

Dear sir/Madam,

Check power supply(SMPS) section.Check/replace all electrolytic capacitor without power capacitor and resoldaring power supply section after then check horizontal output transistor.


thanking you
uttam
[email protected]

problem doesn't seem to be on the power supply board only! had the service center check the high voltage section already? does the popping sound like the one popcorns make?

This looks like a problem with the H Voltage or switching power supply section of the TV set. What you need to do is to measure the voltage from the HV transformer to the Anodes of the CRTs with a high voltage probe, and check the voltage output of the switching power supply. What may have happened is a component may have shorted out causing an over-current condition with is triggering the shutdown circuit (These are the relays you are hearing). I would check the Horizontal Output transistor, and the components in that section of the TV.

In addition check the voltage test points on the HV / Horizontal and switching power supply board. This will determine if the section is working or not (most likely not). Make sure you have a schematic, and multimeter and a high voltage probe.
I hope this helps,
Thank you,
Shuttle83