Sony Tv Wont Power Up

On 7 nov, 17:12, "David B." wrote:stanby light flashes 7 times.

yeah. it's broken.

seriously now, you will need to get in there and measure a few voltages , test a few components and at least give us the chassis reference if you expect any more detailed help than the above!

Flashing LEDs can mean almost anything, from a dry joint to a transformer failure, and are not a relaible guide. If I were you, I would take the set to a local repair place and get a quote, based on proper diagnosis rather than any internet guesswork. The inside of a TV is no place to be if you have no electroncis experience.

best of luck.

-B

And at the very least the diagnosis of a pro will tell you what part needs replacement and you can then ask us here how involved it might be to DIY. Heck, someone may also know the particular component on that board that has failed, based on their history with that model.

good luck!

Are you a technician?

Mark Z.

"David B." wrote in news:f329b$4af59c68$d8ea78d0$ snipped-for-privacy@123.NET:

probably bad electrolytic caps.(ESR)

--
Jim Yanik
jyanik
at
localnet
dot com

Thanks for the replies. The tv has a DA-4 chassis. I'm not a tech but have done some work on guitar tube amps. Tube circuitry is pretty straight forward makes tracing, reading voltages etc easy work . The only real trouble shooting I've done on ic's involved switches and solder joints. Dave

With Sony TV sets, the number of times that the LED blinks, is generally a code to refer you to the faulty area. ISTR that 7 flashes indicates a horizontal deflection failure, so I guess that the first favourite would have to be the HOP transistor short circuit, although be aware that there are issues which can cause transistor failure.

Arfa

"David B." wrote in news:a7c2a$4af61490$d8ea65a1$ snipped-for-privacy@123.NET:

modern TVs use high frequency switching power supplies that depend on low- ESR 105degF electrolytic caps.When the caps ESR climbs,they load supply lines and eventually,the PS control IC current limits,or goes into "burst" mode,where it tries to start,current limits,then retries to start repeatedly. Sometimes,you get lucky and the bad cap(s) are discolored or swollen,easily spotted.Other times,you need an ESR meter like the Dick Smith meter.

Now,the bad caps can be on the secondary side,or they can be on the primary side(or both!),particularly the "housekeeping" supply for the PS controller IC.

Replacement caps -must- be low-ESR 105DegF,or they don't last very long.

To learn about your TV's power supply,find the power supply control IC(it will be near the big line-input electrolytic caps,or near a heatsinked transistor),then Google the datasheet for it.It can tell you a lot.

Sam Goldwasser also has a nice site for troubleshooting.

--
Jim Yanik
jyanik
at
localnet
dot com

Like the driver/driver coupling.

Check the small fusible resistors (0.1 ohm Micron fusible) along the edge of the power supply / deflection board, about 1/3 of the way from the edge of the board nearest the front of the set. They are near 1 or 2 larger black capacitors. Probably the resistors are OK, indicating the FET switchers are OK.

At this point your most likely culprit is IC 8002, an MCZ3001D or DB. Replace only with the DB version. This is a common problem.

Mark Z.

Yes, quite so. Anything in the base coupling circuit which slows the transition of the drive waveform will do it. Also bad joints on the driver transformer when one is used, bad joints on the driver transistor, faulty flyback tuning caps, faulty HOPTx, and incorrect HT volts to name a few more common ones.

Arfa

Worked on quite a few of these the past couple years. IC8002 is a frequent offender. These models are quite different from the standard issue type we've seen for so many years. I'm actually a relative newbie on TV's, having been "promoted" to working on them in-shop with the other guys always out on service calls, but just to give you an idea how different these sets are from the norm, I can tell you the high voltage is a complete separate circuit from the 200 volt line. This is because of the different scan rates supported.

IC8002 provides the PWM drive for the high voltage. IC6501 relates to the

200 volt line. The typical failure mode is that sometimes the set will fire up just fine, then maybe not for days on end, then mysteriously start working again, sometimes for up to a couple months.

If the white 0.1 ohm Micron resistors are OK, then IC8002 is by far the most likely suspect. If the 0.1 resistor associated with that set of FET switchers is open, then of course those transistors are bad. This seems to be the case only very rarely, mainly if the flyback(LOPT) goes tango uniform.

The IC's involved, again are generically known as MCZ3001D and should be replaced with the newer DB suffix model.

Mark Z.

Aha ! I bow to your definitely superior knowledge on this chassis then Mark. It's not one that I've had cause to work on I think - in fact nowadays, I try to steer clear of TV sets altogether. I was just thinking back to all the Sony models with the LED flash codes, and remembering (I think) that 7 flashes was a H def failure, when the HOP and HV were all part and parcel of the same stage.

Arfa

Leave it to Sony to screw things up :)

Does anyone have the Sony blink codes list for a KV-25F1U ?

Mine gave me a fright yesterday afternoon when I got back from work. I switched it on and it just blinked at me. I *think* it was 27 times, but I am not sure.

It died in October 2006 and I had it repaired. Back then I did find a list of the blink code meanings on the net using Google, I think, but this time I could not.

Anyway, I switched the TV RIGHT off (it usually stays on "standby"), let the room warm up (yesterday was easily the coldest day so far this winter), and tried again, and it was fine. No problem today, either.

But I'd be interested to see the list, if anyone can post a copy.

Thanks.

Martin