UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Commodore 1084-D2 Monitor Repair

Argus25 · 17th Jul 2019, 3:40 pm

It appears as though a fast rise high amplitude pulse has found its way into the video circuits/signal. It is driving the CRT beam current to zero followed by an unlocking of the color decoder and some color phase disturbance that then recovers.

Also, the disturbance is about 5 times the vertical scan frequency, an unusual rate as such a signal at those intervals is not normally found in monitor circuitry. While it is possible this fault is in the monitor, most likely the video source (your DVD player)you are feeding the monitor from is defective.

First thing to do is to try a second video source, or second monitor.

If this is a monitor fault, it would be easy to find the cause of this with a schematic for the monitor and following the video signal from the video input with the scope to find where the disturbance is introduced.

17th Jul 2019, 3:40 pm	#2
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Commodore 1084-D2 Monitor Repair It appears as though a fast rise high amplitude pulse has found its way into the video circuits/signal. It is driving the CRT beam current to zero followed by an unlocking of the color decoder and some color phase disturbance that then recovers. Also, the disturbance is about 5 times the vertical scan frequency, an unusual rate as such a signal at those intervals is not normally found in monitor circuitry. While it is possible this fault is in the monitor, most likely the video source (your DVD player)you are feeding the monitor from is defective. First thing to do is to try a second video source, or second monitor. If this is a monitor fault, it would be easy to find the cause of this with a schematic for the monitor and following the video signal from the video input with the scope to find where the disturbance is introduced.