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sansui 7060dx portable dvd player - backlight ok - no image

E

Emanuele Girlando

Jan 1, 1970
0
Everythingelse works. Reads DVDs and plays them. Good audio. Good and
bright backlight.
Just no image. Brightness command has no effect on the backlight as
expected; it has a little effect on screen. With brightness@max I can
see some very lite snow effect on screen.
Having no diagram I don't know how to check signals or voltages. What
I can assume to be microfuses check shorted as expected.
Suggestions?
 
A

Arfa Daily

Jan 1, 1970
0
Emanuele Girlando said:
Everythingelse works. Reads DVDs and plays them. Good audio. Good and
bright backlight.
Just no image. Brightness command has no effect on the backlight as
expected; it has a little effect on screen. With brightness@max I can
see some very lite snow effect on screen.
Having no diagram I don't know how to check signals or voltages. What
I can assume to be microfuses check shorted as expected.
Suggestions?

External video jack problems ? Internal display switched off so that an
external one can be connected ? General software screwup ? Have you tried
removing the battery completely for a half hour ? Tried connecting an
external monitor if it has a jack for one ? Other than these 'simple' fixes,
from experience, it is unlikely that you will get to the bottom of the
problem, particularly without service info, and even if you did, you would
struggle to get individual parts, or in the case of fine pin-pitch quadpak
LSIs that these things invariably employ, have the ability or equipment to
be able to successfully replace them.

Arfa
 
E

Emanuele Girlando

Jan 1, 1970
0
External video jack problems ? Internal display switched off so that an
external one can be connected ? General software screwup ? Have you tried
removing the battery completely for a half hour ? Tried connecting an
external monitor if it has a jack for one ? Other than these 'simple' fixes,
from experience, it is unlikely that you will get to the bottom of the
problem, particularly without service info, and even if you did, you would
struggle to get individual parts, or in the case of fine pin-pitch quadpak
LSIs that these things invariably employ, have the ability or equipment to
be able to successfully replace them.

Arfa

There is an update: the video signal is present and perfect at the
video output jack. The cabling between the mainboard and the tft pcb
checks ok.
Can anybody spend some words about tft drivers?
 
E

Emanuele Girlando

Jan 1, 1970
0
There is an update: the video signal is present and perfect at the
video output jack. The cabling between the mainboard and the tft pcb
checks ok.
Can anybody spend some words about tft drivers?

Yet another update:
the video signal comes out of the video processor. Then it goes to pin
6 of U7, a small IC marked 55TI/JBR. Then it comes out from U7/pin 7
to proceed to the composite video jack where it present and correctly
drives a TV composite video input I get a full color image on the TV).
U7/Pin10 is connected to the TFT driver but no signal is present
there. Shorting U7/pin6 and U7/pin10 a black and white image comes out
on the TFT (at least proving the TFT stuff is working). U7 seems to be
the culprit.
Googling 55TI I was not able in finding anything. The problem is now
related to SMD markings...
Any suggestion about how to proceed?
 
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