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tendi Guest
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Posted: Fri May 02, 2008 7:51 am Post subject: HP 7540 MONITOR |
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My monitor HP7540 is not showing a clear picture, it is de-focussed. The focus pot(fbt) is not very effective. The other problem is that the monitor takes too long to get to its brightness and contrast level. And when it does, the contrast will be less than normal. What could be wrong and can i get a schematic for this monitor?
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fa_07
Joined: 03 May 2008 Posts: 8 Location: Algeria
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Posted: Sat May 03, 2008 8:47 am Post subject: |
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hello.
try to regulate flow and the luminosity and the contrace, by regulating the variable resistors of the VHV (with one turns vice) |
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tendi
Joined: 05 May 2008 Posts: 1
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Posted: Mon May 05, 2008 8:42 am Post subject: |
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fa_07 wrote: | hello.
try to regulate flow and the luminosity and the contrace, by regulating the variable resistors of the VHV (with one turns vice) |
Thanks But I cannot get your message clearly. Where are these variable resistors located? I can access the brightness/contrast settings via software control, I have changed these but no success. |
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fa_07
Joined: 03 May 2008 Posts: 8 Location: Algeria
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Posted: Wed May 07, 2008 8:36 am Post subject: |
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salut.
excuse mopi je ne métrise pas l'anglais
il faut ouvrir l'écran, et dans la carte mére de lce dernier y a la THT,c'est le plus grand dispositif noir,il est entouré par une plaque métalique b(masse).
alors sur la THT ya trois résistances qui se trouve sur la même verticale,comment on repère ces resistances?elles resemble aux vices.éssayez de regler doucement. |
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torbjorn
Joined: 07 Jun 2007 Posts: 370 Location: Sweden
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Posted: Thu May 08, 2008 7:21 am Post subject: |
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Most likely, those symptoms are due to a worn-out CRT or perhaps that the heater voltage is too low.
The heater voltage is normally 6,3 V or 12,6 V , you can measure it at the CRT base. Note that it is in some cases DC, in other cases it might be an AC impulse voltage derived from the horizontal deflection, in that case you need a good DVM with "True RMS" capability to get a correct voltage reading.
In case of a worn-out CRT, it is not worth repairing the monitor. |
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SZASZ
Joined: 27 Apr 2007 Posts: 69 Location: TIMISOARA
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Posted: Tue Sep 02, 2008 6:57 am Post subject: |
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Hello,
Try resolderind the FBT pins.
And then try to adjust focus. |
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