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Component Video cuts out

T

TonyS

Jan 1, 1970
0
Just wondering if any one else has had this happening, or maybe a suggestion on
how to approach this problem:

I started using the component input on my Pavo 32" LCD TV.
Depending on the change in picture brightness the unit seems to lose sync and
switches to "black screen" for a few seconds.
Strong changes from black or white dominated picturs cause problems, otherwise
it works fine.
When the picture comes back it shows the input mode indicator, like it does when
I manually change the input selection.

I suspect that the Y-signal input might be AC-coupled and the picture contents
causes momentary DC level changes which confuse the sync pulse logic.

I have no schematics for the TV. I imagine increasing coupling C value could fix
the problem??

(Other input modes work fine)

Any ideas?

Thanks

Tony
 
S

-=Spudley=-

Jan 1, 1970
0
TonyS said:
Just wondering if any one else has had this happening, or maybe a
suggestion on how to approach this problem:

I started using the component input on my Pavo 32" LCD TV.
Depending on the change in picture brightness the unit seems to lose sync
and switches to "black screen" for a few seconds.
Strong changes from black or white dominated picturs cause problems,
otherwise it works fine.
When the picture comes back it shows the input mode indicator, like it
does when I manually change the input selection.

I suspect that the Y-signal input might be AC-coupled and the picture
contents causes momentary DC level changes which confuse the sync pulse
logic.

I have no schematics for the TV. I imagine increasing coupling C value
could fix the problem??

(Other input modes work fine)

Any ideas?

The lead (conductor) resitance might be higher on the Y-signal causing loss
of signal strength, try changing the colours of the leads around to see if
it follows the Y-Lead ie: Temporarily substitute the lead.
 
T

TonyS

Jan 1, 1970
0
-=Spudley=- said:
The lead (conductor) resitance might be higher on the Y-signal causing loss
of signal strength, try changing the colours of the leads around to see if
it follows the Y-Lead ie: Temporarily substitute the lead.

I already tried changing signal levels via resistors, cause I suspected a
latch-up effect. Smaller signals reduce the number of cut-outs but also the
contrast of course...
 
T

TonyS

Jan 1, 1970
0
TonyS said:
I already tried changing signal levels via resistors, cause I suspected
a latch-up effect. Smaller signals reduce the number of cut-outs but
also the contrast of course...

To honour the big interest in this post I have a follow up:)

I bit the bullet and opened up the guts of the Flatty, and I found:

1. The input selector FET Mux switch (ADG794) can't, according data sheet, even
handle any negative voltage. (abs max -0.3V). Hence the AC coupled 1Vpp Y-signal
will hardly come out OK at the output. Sync pulses are negative....

2. The Signal Processor chip TVP8160 is actually designed to clamp input
signals. If only there was no mux chip first ....
And it is actually designed to handle 576p signals max.

So what does it mean, "HDTV ready" as stated in the TV specs (Pavo PLD-3200)?
Not sure what happens to my 1080i signal.

Anyway, be careful buying stuff on ebay.

Tony
 
T

TonyS

Jan 1, 1970
0
snip

Ah, and btw it draws 57 VA in standby. And it loses the set-up memory when
switched off.
 
S

-=Spudley=-

Jan 1, 1970
0
Runs the other way now when seeing the name "Pavo".
Thanks.
 
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