Sony 27 in. KV-27S26

[Phil]

Hello
I have a Sony 27 in. Model KV-27S26 , lost everything , pulled Power Supply
board out and found Cap. burned and Transistor Q601 with EBC welded together
, used to have SAMS schematics at our local library but they did away with
them, wonder if anyone has a drawing or could give me a ECG/NTE cross
reference for Q601, this transistor drives a small transformer.
Thanks
Phil Lohiser
W8KLK

 

[David]

1. There is no NTE cross for those.
2. You have many more parts than just those two.
3. Proper repair, that does not result in all the parts blowing up again,
requires careful analysis of the SMPS waveform while bringing it up on a
variac.
4. Odds are good that the VDRs in circuit were damaged, and there is no way
to test those, you have to replace them. Will result in all the new parts
failing.
5. Odds are also very good the transformer was damaged when the driver
transistors failed. Again will result in lost parts and time.

The best bet for success is to get a hold of Sony's multi page
troubleshooting guide for the power supply for that specific chassis and use
only Sony exact parts. Others will echo the same kind of sentiment with
that specific power supply design. It will likely cost less in the long run
to have a Sony experienced and trained tech repair this one for you, unless
you have one available in person to help you through the supply.
Just a schematic or service manual on late model Sony SMPS descrete design
is not enough for someone who has not worked on Sony's SMPS design in the
past, the troublshooting training information from Sony is an almost must
have.

David

 

[Phil]

Thanks for the interest in my Sony PS problem , and the thoughtful answer ,
will get problem fixed , am thinking of purchasing a new Sony TV as I really
do like the picture , am wondering if the same weakness is still with these
units or has Sony corrected it.
Thanks again
Phil

 

[Jason D.]

Hello
I have a Sony 27 in. Model KV-27S26 , lost everything , pulled Power Supply
board out and found Cap. burned and Transistor Q601 with EBC welded together
, used to have SAMS schematics at our local library but they did away with
them, wonder if anyone has a drawing or could give me a ECG/NTE cross
reference for Q601, this transistor drives a small transformer.
Thanks
Phil Lohiser
W8KLK

This tell me more than this.

Sony uses two matched transistors (Q601 and Q602) for SMPS. When
something (secondary side loads) shorts out, this always will take
those pair out and fry the 0.1 ohm resistor (as fuse).

This means you do have either bad horizontal transistor (shorted)
caused by solder fractures on the horizontal driver circuits and any
horizontal circuits. Very rarely have vertical IC failure. While in
there, resolder all the power resistors, heavy parts pins etc.

I see this often in Sony sets and many electronic suppliers put
together a rebuild kit for this. Get one from decent supplier and
make sure this supplier is not using generic parts.

Cheers,

Wizard