Dead Sony KV-T25SZ8 TV

In a vacuum?

or the horizontal transformer.

Sylvia.

"Stupider than Anyone Else.

** One of the most common causes of HOT failures.

Dumbass.

.... Phil

Arcing, shorts and HV leakage can all take place within a CRT. I've seen several CRTs that had HV leakage to the Focus element (didn't damage the HOT though).. there may be some examples in the Repair FAQ of this type of fault and other CRT faults.

-- Cheers, WB .............

Thanks.

You mean you have no access to ABSE? Spend $US3.95 at

and get free lifetime access to all the binary groups, limited to 50MB/day.

Clifford Heath.

******Bollocks.

Most horiz output internal resistors are between 25 and 50 ohms. Besides, 20 ohms isn't 5.7ohms. In circuit, E to B reads an ohm or under as the secondary of the horiz driver transformer is directly across it.. Out of circuit, a reading of 5.7 ohms E to B is a bad transistor. It's not common in horizontal outputs, but an E to B short does happen.

**** More likely a stupid answer.

A common problem in Sonys is a bad solder connection on the secondary of the horiz driver transformer, so instead of reading under an ohm, the cold solder causes a reading of several ohms up to the internal resistor value. Simply resoldering the horiz driver will restore proper reading if the output is otherwise OK.

Twit.

Hey, this is fun!!!!!

** Not worth a hoot to me for posting schems or pics unless everyone has the same.

..... Phil

Sony tvs are notorious for being picky about spares. I dislike them for that reason, as they usually get repair estimates rejected due to cost grounds.And that's assuming spares availability...

I recently dumped a 25" CRT set (FE2 chassis I think) - shorted horizontal output stage. Common fault with the chassis - the transformer fails, killing the line o/p transistor and damages the micro. Unless you replace the lot in one go, with genuine sony bits, you're back to square one... plus the uPc is NLA and an awkward smd type. Set was BER, a shame considering it was barely 8 years old.

-B

"Stroonz is a SHITHEAD "

** I have seen them with 20 ohms and less.

You need to get out more.

** The OP corrected her error in the next post - which like a total s*****ad you have not bothered to even read.

The 5.7 ohms was actually measured from C to B.

And the bitch gave no clue about the use of in or out of circuit testing.

** Not all HOT drive circuits are like that.

Many have a low value R in series with the base with a diode across it.

** Why don't you go f*ck a dead donkey ?

...... Phil

ng.

.

Im very annoyed now, I was sipping coffee when I read that, and some got sprayed from laughing ;)

On Mar 14, 9:38=A0pm, "Phil Allison" blathered:

******* Doesn't matter if she corrected it or not. You were INCORRECT when you believed a 5.7 ohm E to B reading was normal in HER SONY.

On Mar 14, 9:38 pm, "Phil Allison" blathered:

** I have seen them with 20 ohms and less.

Yes, and they were shorted. OTOH, if you can cite a transistor that was actually used as a horiz output that has an emitter-base resistor of less than 20 ohms, I'll happily concede.

On Mar 14, 9:38 pm, "Phil Allison" droned:

******** Read above ^

ng.

******** We don't know if she's a bitch or not. She might be quiet pleasant.....

No one said all HOT drive circuits are like that. But again, she wasn't interested in every conceivable version of the drive circuit, she was interested in HER Sony. Her Sony doesn't have a "low value resistor in series with the base". If you don't know what you're talking about or can't offer correct specific information, you really should pipe down, or at least qualify your opinions as just that.

Common Phil, where does one find a dead donkey, even if one was so inclined to be intimate with it. You may not be the smartest guy on the web, but you are a riot!!!

Oh, and the quiet above is a typo: reverse the "e" and "t"

"Stroonz is a PSYCHOTIC SHITHEAD "

** I have seen them with 20 ohms and less.

You need to get out of that asylum more.

** The OP corrected her error in the next post - which like a total s*****ad you have not bothered to even read.

The 5.7 ohms was actually measured from C to B.

And the mad bitch gave no clue about the use of in or out of circuit testing.

** Not all HOT drive circuits are like that.

Many have a low value R in series with the base with a diode across it.

The original exchange was:

" > The horizontal deflection output transistor measures 5.7 omhs from > emitter to base in either direction.

** Probably normal. "

See - no reference is made to any particular set in my remark .

** Why don't you go f*ck two dead donkeys ?

...... Phil

****** Yes, the OP did correct her error, something you refuse to do. You said a 5.7 ohm reading was "probably normal" for her Sony. You were wrong and can't admit it. Nice character flaw Phil.

It's hard to explain this to someone who is unfamiliar with Sonys, but I'll try again: If everything in her Sony is normal, the E to B resistance reading will be under an ohm in circuit. If the secondary of the horiz drive trans in her Sony is open or the connection is bad, it will read the internal emitter to base resistor directly, if the transistor is so equipped. (some Sonys of this era use no e to be resistor). If the transistor is measured out of circuit, it will read approx 35 ohms e to b if it's not shorted. Under NO CIRCUMSTANCES will this TV show 5.7 ohms across the e to b junction. Such a reading is ABNORMAL. Perhaps you left the "ab" out of your reply.

And I know you'll requote her correcting her reading, but it doesn't change the fact that you believed and proclaimed as fact that an E to B reading of 5.7 ohms in HER SONY was normal.

You know, vile, classless folk take all the fun out of a debate.

Enjoy your last word Phil......

"Stroonz is a LYING PSYCHOPATH "

You said a 5.7 ohm reading was "probably normal" for her Sony.

** Wrong.

** Why don't you go f*ck two dead donkeys ?

That's the kind of scenario that's deterred me from replacing the transistor. Your comment about the damage to the microprocessor is particularly relevant given my inability to persuade the set to produce sound with the transistor removed, or even to enter/leave standby mode.

Sylvia.

Not familiar with the set so I don't know exactly - but functions related to sound may be powered from a rail generated from the EHT transformer.

Even if not, it is possible that it may be muted or disabled by the CPU if the EHT circuit isn't working correctly. Many other functions may be shut off for safety also.

In the past I have found that the majority of sets/monitors (note - have not worked on many newer than the 1990's) will work once the H out transistor is replaced, however this isn't always the case. The tuning caps (usually across the transistor) can fail or lose capacitance causing the voltage to go through the roof (they often look normal), yokes can burn out (Samsung, usually inside on the H section where you can't see it without removing from tube, usually from corrosion), the EHT transformer can short internally, or can develop an arc through the plastic casing to chassis.

Arcing from out of the housing on some transformers that contains the focus and screen pots. I have seen often

Some of these arcs can be particularly bad, in fact some seem to manage to burn their way through silicon sealant and continue the arc as before. (note -too close to the frame to allow a decent thickness)

In some cases, the only way I could stop this was to remove the aluminium frame from around the transformer, and cut away a section of it near the where the arc was so as to give the transformer nothing to arc to. It also allowed more clearance for a thicker coat of silcone sealant to prevent future problems.

I am leaving out things like dry joints and obviously damaged components as I assume most people on this group would look for these before posting.

Or just to make the damned thing difficult to diagnose, thus increasing the chance it'll be tossed and a new one bought.

At one point, I saw some of the smoke escape, but unfortunately was on the wrong side of the set to see where it came from :(

Sylvia.

d e .

Years ago they probably realised that the sets were likely to last x number of years, and by that time, few would bother fixing. Once you start using tiny surface mount parts (including those QFP chips) the odds of people not bothering with a repair increase exponentially along with the cost if they do pay a serviceman to do it. Robot assembly also allows things to be packed tighter than manual assembly ?

At the same time the costs of these sets have plummeted. Can remember around 2000 buying a new 25" set, and was over $1000. Within 3 years or so, they were down around $5-600, and now if you can still buy 25" CRT sets, I would be surprised if they were even $150-$200 in discount stores or similar. I doubt you would get a repair done for a fault like yours for less than this at a TV service shop. We have 2 nice Sharp 26" ones in the Garage, that work fine and wont get used by me. Cant even give them away.

Interesting that that link to a manual that was posted really only shows how to change the tube, yoke chassis, front plastic push button assembly - but no schematic or details on board level repair. Maybe they would just send exchange boards during the warranty period.

One big thing that would bother me, is paying for and replacing the transistor, and then finding the problem still there or other faults. You could change the CPU and god knows what else in between and still have a problem.

And short of going over everything with a magnifier and strong light you have buckleys chance of finding it - even that probably wouldnt work.

Had the same recently with a Eaton Powerware UPS. Smoke came out, the thing still "sort of worked" .

Couldnt find the smoke source but found a number of burnt tracks, shorted out 5404 3A diodes, and a FET that was shorted on all 3 legs, the part was unobtainable from regular sources. TO make matters worse, it looked as though the FET was designed to put a dead short across the batteries under some circumstance. The battery was also practically dead.

Getting another unit for about $110 ended up being the best fix.

And indeed discover that the still existing fault destroys them again.

No fuse protecting the battery? Sounds like a serious safety issue - shorting out lead-acid batteries would have to be good way of starting fires.

Sylvia.