Mitsubishi/Acer monitor not powering up fully.

I

Ian Dean

Guest
G'day,

I have a Mitsubishi 1570i monitor that powers to flashing yellow led
only - graphics card had been ruled out. I was wondering if anyone had
a schematic and/or circuit diagram for this or since it seems to be an
acer clone (acer maindboard) the acer equivalent. Suggestions on where
to look for problems would be gratefully received. I do not have an
ESr meter or oscilloscope - but I do have a decent (brymen) auto
ranging multimeter.

Regards and thanks

Ian
 
"Ian Dean" <blackdropbear@netscape.net> wrote in message
news:c7a3405kebe5ljgmhfg9pu1jg71cli146q@4ax.com...
G'day,

I have a Mitsubishi 1570i monitor that powers to flashing yellow led
only - graphics card had been ruled out. I was wondering if anyone had
a schematic and/or circuit diagram for this or since it seems to be an
acer clone (acer maindboard) the acer equivalent. Suggestions on where
to look for problems would be gratefully received. I do not have an
ESr meter or oscilloscope - but I do have a decent (brymen) auto
ranging multimeter.

Regards and thanks

Ian
Click to expand...
Check the horizontal output transistor and soldering in that general area.
Keep in mind that these often have an internal damping diode and resistor so
they'll usually show a C-E short, but B-E and B-C junctions should test ok.
 
The most common causes of failure in these monitors are the horiz output
transistor, (HV drive transistor, if your monitor has a separate one), and
switch driver transistor(s) in the power supply. The flyback and some of the
caps in the power supply and horiz output section are sometimes the cause of
the output transistors in both areas to fail.

The horiz output transistor is difficult to properly test. I would replace
it straight away, and test the switch drivers in the power supply. Then I
would do a complete ESR test on all the caps in the power supply, horiz
scan, HV gen, and the vertical deflection areas. After all the testing is
done, and the mentioned devices have been properly tested, and the suspect
ones replaced, I would then only apply the power back. If something is still
not correct, the new parts will most likely blow instantly on the power up.
Therefore, proper testing and evaluation is important.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Ian Dean" <blackdropbear@netscape.net> wrote in message
news:c7a3405kebe5ljgmhfg9pu1jg71cli146q@4ax.com...


G'day,

I have a Mitsubishi 1570i monitor that powers to flashing yellow led
only - graphics card had been ruled out. I was wondering if anyone had
a schematic and/or circuit diagram for this or since it seems to be an
acer clone (acer maindboard) the acer equivalent. Suggestions on where
to look for problems would be gratefully received. I do not have an
ESr meter or oscilloscope - but I do have a decent (brymen) auto
ranging multimeter.

Regards and thanks

Ian
 
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