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Monitor C1770NSL horizontal problem

 
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Axhpblkpt



Joined: 29 Jul 2009
Posts: 10

PostPosted: Tue Jul 22, 2014 12:00 pm    Post subject: Monitor C1770NSL horizontal problem Reply with quote

Dear Eservice staff,
this Hp MX70 crt monitor has the chassis Lite-On C1770NSL.
In this video you can see the problem.


Here's the schematich.

There are 53V at pin 2 of Flyback Transformer (FBT) when the monitor is off.
There are pulses up to 250V at pin 2 of FBT when the monitor is on. In this situation there is no voltage coming out from pin 4 of FBT.

The fault is intermittent: if the monitor start as it should there are 118V at pin 4 of FBT.

Transistor and diode are not shorted or opened.
I've checked with an LCR meter some polyester capacitor near the FBT, they are good.

Don't know if this is an horizontal or east/west problem.

The voltages 80V, 59V, 11.6V and 7V are ok.
I'll check the horizontal drive with the oscilloscope and post some picture.
All the electrolytic capacitor have been tested.
The entire board and crt board have been resolded.

Can't find the solution.
Thank you for reading.
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