When my 17 inch monitor conked out, I decided to use my old Nec 4fge monitor I had not used for quite some time. I was able to use the nec monitor normally for a couple of weeks. Suddenly the monitor just displays a round white dot in the middle of the screen. Based on my trouble shooting diagnosis, I think the problem is with the HPA100 transistor. Unfortunately,I am not sure this is the problem part. What's the best way of testing this part? I have searched all the nearby electronic stores in the city for the HPA100 part but without luck? If this is the problem part, are there any substitute part that I can use. Any help that you give will be highly appreciated. Thanks in advance.

Hi a dot in the centre of the crt indicates both line and frame scan failure.

So check that the scan coil plug has not worked off the connector or broken joints on the connector.

Rich B

Hi,

Thanks for the help.

Where is the scan coil plug located in the Nec 4FGe monitor? I just want to be sure that I'm working on the correct part. Unfortunately, I don't have the schematic for this monitor.

Thanks again.

Thick wires from the coil on the neck to the PCB usually red + blue wire for line scan and yellow and green or brown for frame scan.

Rich

Sorry, I was away on vacation.

I did what you suggested and now what I'm getting is a thin horizontal white line with some shades of red and blue at the middle of the screen upon power on. The line immediately disappears from the screen after a few seconds.

Is there anything else I can check?

Thank you in advance.

So now you have line/horizontal scan but no frame/vertical scan.

This may also be due to bad connections or a failed frame output circuit.

Rich