Greetings!
While not stricly Commodore hardware, I was advised to post this here, I do recall that the CM8833 was a common monitor for the commodore, though I do admit that I was never an owner! Strictly Acorn in my house in the 80's
Long story short is that I got this monitor along with a computer to use with it for my 50th recently and while it worked ok for about an hour (although with a high pitched whine) it just stopped worked after that short use. The symptons were:-
No power light
High pitch 'race car' noise which slowly lowers in pitch when switched off.
So I’ve had the thing to bits, checked the PSU voltages (ok), replaced the line output transformer and and for good measure the D1577 Output transistor strapped to the side of the heat sink around the LOPT.
The monitor now fires up again to a point, having adjusted the screen POT on the new transformer until I get a clean steady image I find that the monitor has a very low brightness. Any attempt to increase the brightness or the contrast results in the image jumping, sort of growing and shrinking and you get what look like interference lines, I would guess as horizontal hold issues..
I am also told by my kids that there is a very high pitch noise still, though I can't hear that !
I’m kind of at the end of my knowledge at this point and would value some input on where to look next.
Video of the screen output can be seen here - https://www.reddit.com/r/crtgaming/comm ... ir_advice/
p.s. - I do plan to re-cap the monitor, but I didn't want to just keep replacing parts without an understanding of what I was looking at. Just introduces more variables.
Thanks for your attention and hopefully help
While not stricly Commodore hardware, I was advised to post this here, I do recall that the CM8833 was a common monitor for the commodore, though I do admit that I was never an owner! Strictly Acorn in my house in the 80's
Long story short is that I got this monitor along with a computer to use with it for my 50th recently and while it worked ok for about an hour (although with a high pitched whine) it just stopped worked after that short use. The symptons were:-
No power light
High pitch 'race car' noise which slowly lowers in pitch when switched off.
So I’ve had the thing to bits, checked the PSU voltages (ok), replaced the line output transformer and and for good measure the D1577 Output transistor strapped to the side of the heat sink around the LOPT.
The monitor now fires up again to a point, having adjusted the screen POT on the new transformer until I get a clean steady image I find that the monitor has a very low brightness. Any attempt to increase the brightness or the contrast results in the image jumping, sort of growing and shrinking and you get what look like interference lines, I would guess as horizontal hold issues..
I am also told by my kids that there is a very high pitch noise still, though I can't hear that !
I’m kind of at the end of my knowledge at this point and would value some input on where to look next.
Video of the screen output can be seen here - https://www.reddit.com/r/crtgaming/comm ... ir_advice/
p.s. - I do plan to re-cap the monitor, but I didn't want to just keep replacing parts without an understanding of what I was looking at. Just introduces more variables.
Thanks for your attention and hopefully help
