[TechAssist] SONY KV35S66 CHASSIS AA-2D need print
- From: Jorge Camboni <geo@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Wed, 11 Jun 2003 19:34:20 -0500
>
Hi techs. I'v been struggling with this (exceptionally) heavy
Sony KV35S66 set at the customer's home.
apparently, there is a problem with the vertical output. The output
IC is a TDA8172 and it is fed by +15 -15 volts originated in separate
flyback secondary windings. The PROBLEM ITSELF IT IS THAT
THERE IS NO PIC, NO RASTER unless you advance the G2 control,
the voltage on the 3 colour cathodes being over 200v (no video drive at all)=
..
but when you advance the G2, the picture is a milky rainbow pattern
just like the old magnavoxes with one of the vertical psupplies bad,
because there is a 9VOLTS DC BIAS across the vert. yoke (there's
actually no vertical deflection, just a strong dc bias on the yoke)
and the set is protecting itself cutting any video output. ...
Well, I changed the tda8172 first.. no luck, then rechecked
both power supplies and they are somewhat asymetrical, the
positive being 11.6v and the negative 16.5v, that is quite a difference
but resistor, diode and caps are just fine on both, and unless on of
the flyback windings is bad, IT SEEMS THAT THE POSITIVE
POWER SUPPLY IS BEING DRAINED MORE HEAVILY, hence
the voltage difference. I checked all I could at the customer's location
and in this case I am unable to bring it to the workshop. I suspect the=
jungle
IC but I wont=B4t spend that money unless I am pretty sure of it. Need the
schematic to go deeper into matters, but I had to give him a rather low
estimate in order to do the job (big mistake)
If anybody could help with a print, or a clue on this case, I' d appreciate=
it
very much
TIA Jorge
Jorge Camboni, GY Electronics, Richardson, TX
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