Hey!
Just turned the big 50 and my sister got me the best present ever, a semi broken computer from my childhood![:-)]( "Smile")
. (Acorn Archimedes)
The CRT that came with it worked for about an hour and then stopped with the old high pitch whine, no picture and no power light.
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’m kind of at the end of my knowledge at this point and would value some input on where to look next.
Is it possible I got a D1577 transistor with different specs? Are there other parameters that matter ?
Thanks in advance !
Video of the screen output can be seen here - https://www.reddit.com/r/crtgaming/comm ... ir_advice/
Just turned the big 50 and my sister got me the best present ever, a semi broken computer from my childhood
. (Acorn Archimedes)The CRT that came with it worked for about an hour and then stopped with the old high pitch whine, no picture and no power light.
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’m kind of at the end of my knowledge at this point and would value some input on where to look next.
Is it possible I got a D1577 transistor with different specs? Are there other parameters that matter ?
Thanks in advance !
Video of the screen output can be seen here - https://www.reddit.com/r/crtgaming/comm ... ir_advice/
Statistics: Posted by L4nder — Mon Jan 20, 2025 9:41 pm