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HP 7540 MONITOR

 
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tendi
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PostPosted: Fri May 02, 2008 7:51 am    Post subject: HP 7540 MONITOR Reply with quote

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

PostPosted: Sat May 03, 2008 8:47 am    Post subject: Reply with quote

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

PostPosted: Mon May 05, 2008 8:42 am    Post subject: Reply with quote

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

PostPosted: Wed May 07, 2008 8:36 am    Post subject: Reply with quote

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

PostPosted: Thu May 08, 2008 7:21 am    Post subject: Reply with quote

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

PostPosted: Tue Sep 02, 2008 6:57 am    Post subject: Reply with quote

Hello,

Try resolderind the FBT pins.

And then try to adjust focus.
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