HI Mario,

It can be due to eeprom ic already corrupted or the contrast circuit.

Jestine

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Hi Anbu,

It could be low B+ supply voltage or the modulation diode/pincushion transistor have problem.

Jestine

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---------Thanks!

I have vl 500, crt monitor , made in thailand, from chuntax electronics pvt ltd, for which i require guidance on proper repair.
I am using my 650 mhz processor speed computer with a CRT monitor, Its screen got to the left side leaving a one inch black blank space in the left. I got that monitor like that. its menu buttons for a series of functions such as position, size, geometry, colour etc were not working , so i decided to open the plastic case, and removed the dust etc, After no of attempts to identify any one particular variable resisitor responsible for moving the screen to the left side , i found one , after rotating it with screen driver , the screen filled the space in the left side, but when I closed the case, suddenly the screen shrunk into the middle, creating about four inch blank space on both sides, When i gave some light jolts to circuit board, the screen suddenly became normal, but it would then shrink again into the middle , situation further deteriorated when I adjusted few more variable resisitors responsible for screen adjustment. the picture finally disappeared and then zig zag colourful lines started to appear,

-----------I suspect that is a dry joints in the flyback area. Try look for any dry joints in the modulation diode or even the B+ fet circuit

I took it to a repairman, and he asked me to come after two hours, I reached him after two hours, fortunately he repaired the all buttons, which started to show menu index, but cut those earth wires which were connected between picture tube glass and a metal on a circuit board. he also removed a metal shield of the electron gun circuitory board,

------Noted.

However the picture has reappeared, but not that much crisp , further on increasing brightness, the blank black space turns into darker greenish with horizantal lines, where ,

------This could be a sign of weak tube.

there is no video input signal, sometimes while windows xp restarts sounds like kitik are also heard.

-------Sound could be come from a flyback please check on this link:
http://www.electronicrepairguide.com/testing-flyback-transformer.html

further if i switch off the monitor with button, the screen vanishes with a white vertical line and with a dot of white light appearing right in the middle.

-------This could be a sign of weak tube.

Jestine

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I am munsif ali from pakistan. i have a contrast problem oupled with other problems. your above information was indeed very helpful.

I have vl 500, crt monitor , made in thailand, from chuntax electronics pvt ltd, for which i require guidance on proper repair.

I am using my 650 mhz processor speed computer with a CRT monitor, Its screen got to the left side leaving a one inch black blank space in the left. I got that monitor like that. its menu buttons for a series of functions such as position, size, geometry, colour etc were not working , so i decided to open the plastic case, and removed the dust etc, After no of attempts to identify any one particular variable resisitor responsible for moving the screen to the left side , i found one , after rotating it with screen driver , the screen filled the space in the left side, but when I closed the case, suddenly the screen shrunk into the middle, creating about four inch blank space on both sides, When i gave some light jolts to circuit board, the screen suddenly became normal, but it would then shrink again into the middle , situation further deteriorated when I adjusted few more variable resisitors responsible for screen adjustment. the picture finally disappeared and then zig zag colourful lines started to appear,

I took it to a repairman, and he asked me to come after two hours, I reached him after two hours, fortunately he repaired the all buttons, which started to show menu index, but cut those earth wires which were connected between picture tube glass and a metal on a circuit board. he also removed a metal shield of the electron gun circuitory board,

However the picture has reappeared, but not that much crisp , further on increasing brightness, the blank black space turns into darker greenish with horizantal lines, where , there is no video input signal,

sometimes while windows xp restarts sounds like kitik are also heard.

further if i switch off the monitor with button, the screen vanishes with a white vertical line and with a dot of white light appearing right in the middle.

now my question is under such a situation , which parts of the circuit board will you suggest me to replace,

regards

munsif ali, age 40,
commerce graduate,
923313524436
d-36, navy housing scheme, karachi

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