AOC spectrum 7GLrA, no Color Display

[FRick]

I have a "AOC spectrum 7GLrA" monitor, the problem is No display or even a small fliker on the screen when turning ON. the Relay seems to be working i can hear and feel the switching when turning ON, the LED above the power switch is lighting also green when ON and orange when OFF, I can also hear the voltage turning "ON" in the degaussing coil, only No display.

please help!


Thanks
frick

[Guest]

Does the OSD (On Screen Display) work? Have you tested the videocard in your computer by plugging another monitor into it??

[FRick]

Yes, I'm sure No problem on Video Card, cause it works in other monitor.

This monitor was the problem, for even the VGA chord is not plug to the video card it should have a color pattern that will display after a minute of turn ON, but nothing display so it should be in this Monitor.
I'm not Sure with OSD that you are telling but i tried pressing this OSD button beside the power switch but nothing happens.

Thank you for your interest in helping me in this problem. My Background is TV repair and been able to fixed some minor computer monitor problems, except for this. I tried to looked for any troubled part inside the best of my knowledge but no luck, I would appreciate any help of idea contribution.

By the way this monitor is mine, its a big SHAME on me for i been able to repair some monitor of other but i can't repair mine...


Thanks,

Frick

[sparky]

As you mention degaussing I would then assume it is a crt monitor and in this case would be similar to a t.v and should find fault finding techniques similar.
Download the manual from this site for aoc 7glr and compare this to yours and check the h.t followed by the usual horizontal output transistor/transformer stages unless eht present and if so frame circuit etc.
_________________
If in doubt pull the plug out.

[FRick]

Yes, its a CRT and i think your right, i have gone checking the horizontal circuits and they work, i even check the "cap" of the flyback and it holds a charge, so i'm assuming that horizontal circuit was working.

Can you explain to me what this "frame circuit" is? Is this the circuit that is doing the color pattern? where could i found this? is it in the main board? or in the board at the back of CRT? Sorry i'm not familiar with it. I'm a very much interested to know about this.

Thank for the idea,

rick

[sparky]

The frame circuit is just another name for the vertical deflection circuit.

To check the horizontal circuit.
If you have an oscilloscope you will see line pulses by moving the probe NEXT TO and not touching anything near the line transformer (alternatively a neon screwdriver will light up aswell as a rough guide) if the horizontal is working or may feel static on the screen when set initially started.

To check the vertical/frame circuit the line transformer will have two adjustments. One for "focus" and one for "screen". Mark the position of the sreen control and then advance clockwise to see if a horizontal line is displayed and if so the vertical output circuit requires investigation starting with the supply to this.

If a full screen is shown then check all supply rails and in particular those supplying the video stages/tube drives.

Incidentally I assume it is not something silly like damaged/bent pins that plug into the p.c on the D plug.
_________________
If in doubt pull the plug out.

[Guest]

Thanks for this appropriate idea that you are sharing me. I did the neon test on the flyback putting a neon screw near the heavy wire and your right it lights up. What i'm not sure now is the "screen" adjustment on line transformer (is the line transformer the same as flyback?). I will try to adjust that this afternoon since i'm in work today. I have already attempted to adjust that before but it was glued a little so i didn't continue.

If the Horizontal and Vertical circuits work, is there any other circuit that is possibly blocking the display of Color patern or the lighting of the screen? Can you share to me what are about video stages/tube drives. If you could tell me some proceedures in testing the voltage of this stages. They might be sligthly different from T.V. or you have a better techniques in doing this.

Thanks in advance,

Rick

[FRick]

Oh! forget to sign In , Thats me


Rick

[Guest]

DPMS

Display Power Management Signaling.

It is the computer that brings the monitor in and out of sleep mode. The horizontal and vertical sync pulses are supplied from the computer.

When the computer goes into 'Standby', the computer switches off the horizontal sync pulse. Minimal power savings.

When the computer goes into 'suspend', the computer switches off the verticle sync pulse. Typically <15Watts

When the computer wants to turn the monitor off, it switches off both the horizontal and verticle sync pulses. Typically <8Watts

The monitor's microprocessor interprets these signals (or lack thereof) and shuts down the appropriate circuits.

There is usually a transistor for each mode that the microprocessor controls, that switches the powersupply into standby, if you bypass it and your monitor works, you will know your problem is with these circuits.



Let us know what you find.

[Guest]

Many Thanks to all your ideas,

After a lot of testing and trouble shooting in this monitor basing from all of your ideas, I made it to display a 2.5 inches screen near the top of the whole screen area. And as i feel the vertical IC it becomes very Hot, (i mean its not a normal temperature of an IC its very hot, almost cannot touch). I'm sorry i forgot to take the number of the IC, but does this mean that this IC needs replacement? Should i consider the Yoke Coil? (I'm a bit hesitant to remove or break the paste of the yoke coil to the tube since this was tricky to put back the original alignment later)

I'm planning now to replace the IC and hope it will work.

Thanks thanks thanks.

rick