Blown HOT in Sony KVT-29SZ1

Hi I have a Sony KV 29SZ1, (Perth Australia) with a ticking or clickin

noise, no picture and no sound. It looks like at this stage the proble is in a fuse, my question is how can you tell which one it is, I ca hear the thing ticking away but I just can't locate it (I have remove the TV cover)...

I have a Sony KV 29SZ1 that has a blown HOT. It is owned by my apprentice who doesn't have a great deal of cash to throw around, so I told him to bring it into work and we would have a go at fixing it.

The fault was simple, would not turn on. I opened it up and put the meter across B+ - 0v. I could also hear it ticking. So the first thing I did was pull out the HOT and test it, sure enough it was SC. I sent the the young fella out to buy a new HOT which turned out to be AU$30.

So, the question I ask is: Is there in easy way to tell if the LOPT is the reason the HOT has failed? I don't really want to put the new part in if it is going to blow straight away. I was thinking about putting it in and bringing up the power slowly from a variac. Will this help?

TAI,

AP[/i Wrote:

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sigmma

sigmma: No offence intended, but based on your inquiry you would be best advised to IMMJEDIATELY replace the TV cover and at the very least TAKE it to a repair shop for a repair cost estimate by a tech that has actually opened er up and performed some technical troubleshooting and testing so you can make an intelligent repair decision with facts instead of wild guesses. The insides of televisions are a dangerous place.... if you want to research this further you should go to the website for this newsgroup at

there with some searching you will find a wealth of repair data and IMPORTANT SAFETY information.

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Best Regards,
Daniel Sofie
Electronics Supply & Repair
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"sigmma"  wrote in message
> Hi I have a Sony KV 29SZ1, (Perth Australia) with a ticking or clicking
> noise, no picture and no sound. It looks like at this stage the problem
> is in a fuse, my question is how can you tell which one it is, I can
> hear the thing ticking away but I just can't locate it (I have removed
> the TV cover)...
> sigmma

Replace the H-transistor, but do not solder the collector terminal - route this via a 60W bulb which will limit the current if the LOPT has shorted turns. If this arrangement fails to develop a voltage across the LOPT primary - don't despair, it could be a S/C rectifier for a scan derived supply, just follow the tracks away from the LOPT and look for diodes to test. Another common cause of H-transistor failure is the flybak tuning capacitor - this is often a disc-ceramic type (normally go S/C and split/burn!) the regular high voltage wound foil types commonly fail O/C and allow the peak flyback voltage to exceed the H-transistor's Vceo!

Caution - examine the flyback tuning caps first - the current limiting lamp won't protect the transistor from excessive flyback if it fires up!!!

Good question on that HV caps in horizontal circuit, what is the method of checking them? I have capacitance meter but I know better not to trust that, cap could fail under load (even instantly) and pass a cap meter test?

Cheers, Wizard

That's lead free solder for you! Since its introduction reliability has plummeted so far that some 5x as much electrical equipment is going into landfill!!!

Lead was mined from the earth in the first place, and that's eventually where itends up back. Just like the run off rain and the weather washes from lead roofing and the pellets from 12bore guns used for bloodsports - which the brain-dead beaurocrats seem to have overlooked!!!

Given the cost of the H-transistor, test by replacement is probably the safer option.

Do you have a reference for that figure?

Tim

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Did I really still have that sig?

Daniel Many thanks for your advice, I know that the inside of Tvs are a really dangerous place, thats why I have decided to unplug the unit from the wall before touching the flyback with my bare hands.....just kidding!!! now seriously, since I dont have a diagram for my Tv I have decided to search for a faulty unit on ebay, Do you guys think that if someone is selling a faulty unit and the fault being something like colour fading, then the cause would be an aging tube and the chassis will be more o less fine.....so if I replace the chassis from a another tv then I'll have my Tv back....posible?????

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sigmma

Some less reputable service engineers make their living this way.