[TechAssist] Re: Sony KV32FS12 BA5 no picture
- From: "Damon" <damon101@xxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Sun, 3 Apr 2005 08:30:04 -0500
There is something that might help to see if IK has feedback. Switch to
Video 1 with no signal on it. Scope the CRT cathodes looking for the IK
pulse and blanking pulse, when you see it, adjust the screen control up and
down a bit---you should see the IK pulse shift up and down too, along with
the Cathode voltage's black/cutoff level.....if there is feedback you should
see the IK pulse height and the CRT cathode voltage shift higher/lower as
you adjust the screen voltage.....the cathode voltage will try to cutoff the
tube and the IK will try to find the conduction/cutoff point if it is
properly "feeding back" to the video IC.
It just means the path is working, not that all components are right on
target....my experience has been the video jungle may be bad, BUT there is
the possiblility too (on some Sony sets) that if there is a standup board
labled B-something (BR? BK?) that may affect video......The FS series does
not have this board if memory serves me correctly, but we have had 2 PTVs
recently with bad BR(?) boards.
Now back to the problem.....higher cathode voltage, lower input voltage,
lower feedback voltage, initial thought is the screen voltage is too
high....I think it should be set around 300 - 350V , no more than 400 on an
older CRT. Set it for 325, I think that's what I normally see on these.
Now on this set, does the CRT output IC pass the IK pulse directly to the
video jungle (on the feed back loop) or does it pass thru an "IK buffer"
transistor....sometimes that transistor won't properly buffer, but its rare.
Damon Brunger
Telrad Electronics
Fort Wayne IN
----- Original Message -----
From: "Peter oliver" <oliver_peter1@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Saturday, April 02, 2005 6:51 PM
Subject: [TechAssist] Re: Sony KV32FS12 BA5 no picture
> I have the sony Schematic. Just in the process of indecison on if the
jungle
> is causing or if the IK shut off the jungle due to bad CRT. It does give
> what appears to be a blink code of 5 blinks. Voltages on the CRT RGB
drive
> out (at IC702) are reading 70V or so higher than scheamtic. IK voltage is
> lower and the input voltage reading to IC702 are slightly lower.
>
> Peter Oliver
> Tucson Radio TV
>
> From: John Mikowich <spacenut@xxxxxxxxxx>
> Reply-To: techassist@xxxxxxxxxxxxx
> To: techassist@xxxxxxxxxxxxx
> Subject: [TechAssist] Re: Sony KV32FS12 BA5 no picture
> Date: Sat, 02 Apr 2005 18:35:16 -0500
>
> Peter oliver wrote:
>
> >Sony
> >KV32FS12
> >BA5
> >DEC 2000
> >
> > No Picture, turning up screen control gives retrace lines
> >(Colors are shifted) and a faint ghost image. Scoping the Drive to the
CRT
> >No RGB drive of consiquence. IC301 Jungle CXA2154AS has video input and
> >output but No RGB out. Replace IC702 TDA6108 and added C702 per service
> >bulitien. Has anyone seen many jungle failures on this model? This set
> came
> >back from Guam a month ago and just apparently failed a few days ago. No
> >apparent PCB cracks.
> >
> >Peter Oliver
> >Tucson Radio TV
> >
> >
>
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> Hi Pete:
>
> Have manual if you need! Send me email add will send. Approx. 10 meg?
>
> John Mikowich
> East Side Tv.
>
>
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