7409 is wrong part, change it to 7406.
On Tue, Mar 26, 2013 at 7:14 AM, Carlos Rubio <csrubio@gmail.com> wrote:
> Hello, I'm working on a Vectorbeam monitor on which I've replaced about
> 90% of the components. This monitor is the "discrete" version with the HV
> components on the monitor PCB. It also uses the older part numbers.
>
> Currently the screen is blank, but I'm not sure if it's a problem with the
> intensity circuit or a legitimate spot killing. Jumpering Q2 (labled Q24
> on my board) causes the picture to appear and reveals that the top half of
> the image is missing. All transistors have been replaced.
>
> I should also mention that this monitor has a 7409 at IC7 (labeled U6 on
> my board) instead of the 7406 referenced in every document and schematic
> that I've seen. There are diodes between pins 1 and 8 and 3 and 8 as seen
> here<https://lh3.googleusercontent.com/-aQ9D82rvVr4/UVGOweZsPXI/AAAAAAAAKBk/E1w6AkFky-g/s895/IMG_0007.JPG>.
> I've replaced the 7409 and the diodes with new ones, exactly as they were.
> The symptoms were the same before and after.
>
> I'd appreciate any insights in understanding if one problem is related to
> the other, and how to narrow down the fault(s). Thanks,
>
> Carlos
>
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Received on Tue Mar 26 10:07:06 2013
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