Hello everybody. I'm her to ask you about a problem i can figure out. I
have an AOC Model 5E monitor, it turns on, High voltage is there, and
scan (raster) works, but the image it displays is so dark that it
almost can be viewed. If i push up the screen pot in flyback, the
background brightness goes up, but dhe image dont get better, even when
retrace lines appears, so is no a flyback fault. It looks more like an
video amplitude problem, but i'm not shure. The brightness and contrast
controls work fine, but is like the overall values of video amplitude
are too low.I`v read a lot about it, and now i'm onfused.I checked de
ABL, and adjusting it=B4s level it gets better, but no enough. I got an
diagram from eserviceinfo.com, bt it's no accurate (there are entire
changed stages),but it=B4s pretty close. However, the voltages i measure
are few different from the showed there, and i have no means to know if
it is a design difference or an anomaly. Now i show the values i get
from the tube terminals, all taken with an ancient digital FLUKE
multimeter, in DC Voltage mode:

G =3D 67 V
B =3D 68 V
R =3D 68 V
G1 =3D -27 V
G2 =3D 264 V
Heater=3D6,07 V

In the video stage it uses LM1279 as driver and LM2438 as power output.
The supply voltages for this one look normal (15 and 75 V)
I don=B4t know what else can i explain.

Besides, i got an similar problem with an Hurricane Systems Model
MT-14SV28NI, but it show intermitent. This one uses the LM1203N and
LM2406T pair.

This has become an mistery for me, any help or advice will be welcome.
I'm thinking about change the video output ICs, but first i better look
here for some answer.

Well, giving thanks from now, i say goodbye.

JCVH - ERDM

wrote in message
oups.com...
Hello everybody. I'm her to ask you about a problem i can figure out. I
have an AOC Model 5E monitor, it turns on, High voltage is there, and
scan (raster) works, but the image it displays is so dark that it
almost can be viewed. If i push up the screen pot in flyback, the
background brightness goes up, but dhe image dont get better, even when
retrace lines appears, so is no a flyback fault. It looks more like an
video amplitude problem, but i'm not shure. The brightness and contrast
controls work fine, but is like the overall values of video amplitude
are too low.I`v read a lot about it, and now i'm onfused.I checked de
ABL, and adjusting it´s level it gets better, but no enough. I got an
diagram from eserviceinfo.com, bt it's no accurate (there are entire
changed stages),but it´s pretty close. However, the voltages i measure
are few different from the showed there, and i have no means to know if
it is a design difference or an anomaly. Now i show the values i get
from the tube terminals, all taken with an ancient digital FLUKE
multimeter, in DC Voltage mode:

G = 67 V
B = 68 V
R = 68 V
G1 = -27 V
G2 = 264 V
Heater=6,07 V

In the video stage it uses LM1279 as driver and LM2438 as power output.
The supply voltages for this one look normal (15 and 75 V)
I don´t know what else can i explain.

Besides, i got an similar problem with an Hurricane Systems Model
MT-14SV28NI, but it show intermitent. This one uses the LM1203N and
LM2406T pair.

This has become an mistery for me, any help or advice will be welcome.
I'm thinking about change the video output ICs, but first i better look
here for some answer.

Well, giving thanks from now, i say goodbye.

JCVH - ERDM

Not familiar with the model, so it's difficult to be precise. However, your
G2 voltage seems a bit low - so I would guess that the problem is around
there. On some flyback transformers there is a pot to adjust this, and this
may need a bit of a tweak. Often there are two pots - one for the focus and
one for the A2 (anode 2) - you won't harm anything by adjusting these,
except perhaps yourself so be careful what you touch. If it won't adjust up
it may be that a high value resistor supplying the anode has gone high, or
even open.

" bravely wrote to "All" (15 Sep 05 15:23:31)
--- on the heady topic of "AOC 5E monitor with very dark image."

Check the video processor IC's supply voltage. I've seen the same dark
image symptom before where the video IC supply rectifier had gone high
resistance because the filter electro had been installed with reverse
polarity at the factory.

A*s*i*m*o*v


El From:
El Xref: core-easynews sci.electronics.repair:342222

El Hello everybody. I'm her to ask you about a problem i can figure out.
El I have an AOC Model 5E monitor, it turns on, High voltage is there, and
El scan (raster) works, but the image it displays is so dark that it
El almost can be viewed. If i push up the screen pot in flyback, the
El background brightness goes up, but dhe image dont get better, even
El when retrace lines appears, so is no a flyback fault. It looks more
El like an video amplitude problem, but i'm not shure. The brightness and
El contrast controls work fine, but is like the overall values of video
El amplitude are too low.I`v read a lot about it, and now i'm onfused.I
El checked de ABL, and adjusting it4s level it gets better, but no enough.
El I got an diagram from eserviceinfo.com, bt it's no accurate (there are
El entire changed stages),but it4s pretty close. However, the voltages i
El measure are few different from the showed there, and i have no means to
El know if it is a design difference or an anomaly. Now i show the values
El i get from the tube terminals, all taken with an ancient digital FLUKE
El multimeter, in DC Voltage mode:

El G =3d 67 V
El B =3d 68 V
El R =3d 68 V
El G1 =3d -27 V
El G2 =3d 264 V
El Heater=3d6,07 V

El In the video stage it uses LM1279 as driver and LM2438 as power
El output. The supply voltages for this one look normal (15 and 75 V)
El I don4t know what else can i explain.

El Besides, i got an similar problem with an Hurricane Systems Model
El MT-14SV28NI, but it show intermitent. This one uses the LM1203N and
El LM2406T pair.

El This has become an mistery for me, any help or advice will be welcome.
El I'm thinking about change the video output ICs, but first i better
El look here for some answer.

El Well, giving thanks from now, i say goodbye.

El JCVH - ERDM

.... If plugging it in doesn't help, turn it on.