[TechAssist] Re: Dell Ultrascan 20TX, 1997 19" computer monitor, low screen voltage, need schematic

Kevin, is there a fan in the unit? If so the fan might be dead, causing 
the shutdown. Also, try changing that 2.2 meg resistor even though it 
checks ok. I'm not really familiar with the circuit, but it sounds a bit 
strange that there is a transistor connected to the G2. Can you verify 
that? Is the transistor pulling the G2 down to 4V?

Are the any other model/ chassis numbers? It might be a Sony chassis.




Gary McCartney

McCartney Electronics
Guelph Ontario Canada
Est. 1984
email: gary (at) number63.ca








Kevin wrote:
> This monitor comes on with HV, filaments, and no video for about 5
> seconds and then it goes into shutdown with an amber light flashing.
> The screen voltage or G2 measures only 4 volts and then drops to zero
> when the monitor goes into shutdown.  I found 790 volts on one end of
> R463 and 4 volts on the other end.  The 4 volt side is connected to G2
> on the picture tube and to the collector of Q403, a C4686 transistor.
> R463 measures correctly out of circuit at 2.2 meg ohms.  
> 
> Kevin Wilks
> Kevin's TV & Video Repair
> Penticton BC Canada
> kevintv@xxxxxxx 
>  
> 
> 
> 
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