My Sony TV is broken again.

[audioguru]

Boo-hoo.
My 32" Sony TV is 8 years old and stopped about 3 months ago. The two power converter transistors, a fusable resistor feeding them and the horizontal output transistor failed. I checked everything and nothing else looked nor measured bad so I got replacements from Sony and the TV worked perfectly for about 40 hours, then it stopped again with exactly the same failures. No smoke.

Is something intermittent? A capacitor shorting or opening occasionally or the windings in the horizontal output transformer?

Is my thermal compound no good? The original thermal compound was all dried up and hard as a rock. I had to carefully scrape it off. My new stuff is still like grease. The new parts must have reached their max operating temperature many times.

Is it worth fixing again?

 

[HarveyH42]

What happened when it failed? Just lose picture. Picture go very bright? Everything just shut down? I'm not a technian or anything, but have never bought a new TV, so have fix several over the years. Guessing you spent $40-50 on parts/shipping, ect... through the manufacturer. Replacing the parts again, without finding the cause isn't going to do any better. Depends on your budget and how important TV is to your lifestyle. A new 32" goes in the $200-300 range. A repair shop will likely charge around $100. See if you can find a SAMS photofacts for your model, they are pretty good troubleshooting guides. If you can't find it, then it usually isn't worth fixing...

 

[audioguru]

My TV just blew up its parts and shut down. Twice.

I got the Sony service manual from the internet. Forums have guys talking about fixing the same TV and the same problems. Some guys say to change certain capacitors. Other guys say to change different capacitors. Somebody said to change the horizontal output transformer. I don't see how a capacitor can work fine then suddenly fail, then the same capacitor works fine for 40 hours then fails again.

I have seen the CHEAP, CHEAP, CHEAP Chinese 32" TVs for about $250 but they are crap. I bought a little Chinese 13" colour TV for only $59 for my wife to watch (it is too small for both of us to watch) in the meantime.

 

[Nigel Goodwin]

A common problem is dry joints on the line driver transformer, examine them closely with a magnifier and see if you can see any sign of the joints been bad. This is a VERY common cause of blowing the line outputs, if it's not that, it's usually the LOPTX.

 

[on1aag]

Sony is crap.

Hi Audioguru,

The LOPTX was also my first idea, remove it from the board and clean it.
Inpect it carefully and see if you can find any cracks in the plastic.
If you can't find any doesn't mean that the LOPTX is ok, but if you do . . .
I would have replaced it together with the defective parts.
You still have one small chance, measure the horizontal output transistor.
If it's a dead short it's probably LOPTX related. If you can still measure
some resistance between collector and emitter, say 10 hm: or so, it's
the capacitor accross the c-e terminals of this transistor which is
defective, not short and not necessarely open circuit.

Good luck,

on1aag.

 

[audioguru]

The first blown horizontal output transistor is 0.6 ohms between base and emitter and is 28 ohms between collector and emitter. Its collector-emitter rating is only 600V but the waveforms in the manual shows a 1070V pulse. Go figure.
I'll look at the circuit board and transformers in the morning with better lighting.

 

[mojat]

Hai guru, this is your friend mojat. I too came across this problem. First the power transistors are 2sc4161 and if so replace it with the same ones and check the dc output(B+) going to the collector of Horizontal output transistor and make sure that it is around 135-140v and if is is high change capacitors at the power stage not the main dc filter. Then if the dc output is ok you replace the H output transistor. Also check the Fet which is near the output transistor used in H width circuit and make sure that it is not shorted or leaky, because in both cases your TV will work but the output current will be more and the Tv will give you trouble because the H output transistor will get over heated and fail. I replaced the FET with 2sk1012 and it is now working well. I tried for the genuine FET with sony and it was out of stock. So try this and let me know.

 

[Tvtech30]

Follow the p-c foil from the base of the Hor out transistor though a resistor then to a small transformer [ Horizonal dr transformer ] Inspect the connections on this transformer real good. If you can verifly a poor connection on one of the pins on this transformer,then this was the cause of the other part failure's..also try this site www.bdent.com for Good replacement parts at 1/2 of sonys price's.......

 

[HiTech]

Fixed many Sonys here. First of all do the obvious in inspecting all solder connections, esp. near heat generating components. Second, assure that your power supply section (regulator especially) is up to snuff. You should be able to isolate the output of it from the rest of the PCB. You can sub the voltage from an external DC supply if you have one that goes up that high to see if the rest of the set runs ok. Also check the HV anode wire as on some Sonys sets they develop a low resistance internally often leaving folks to believe the flyback is bad (well actually it is at that point!!). In the end it's best to stick with OEM Sony parts, esp. their semis and for what you pay for those, it's imperative that you resolve things to assure the TV repair will last! Take your time.

 

[Tvtech30]

HITECH, Could you elaborate a little more on this anode [wire] reading a low internal resistance? Also the Pwr supply outputs, a switched 5 v standby 5 v 9 v 129 v all are needed to run system control,hor osl & drive stages along with voltages to run hv / def / scan and other circuits. Little bit of a trick to sub in all these supplies and at the right sequence.. And as far as sony parts go, If they are from Japan they are good. As these are what the more higher end electronic Mfg's use.