So I acquired my Macintosh SE back in early 2017, when it was fully functional and usable. Since then there have been numerous problems with the machine, the hard drive failed first and it took until recently to replace it with a 50 pin Quantum LPS drive, the floppy drive failed after shortly after the hard drive and was replaced promptly and then the screen began displaying an unusual pattern out of the blue. The images, albeit of relatively poor quality due to my lack of a good digital camera- I am a strong believer in photographic film, attached show the patterns. The startup bong occurs and the computer does boot, but the screen is very bright and it is hard to see the desktop. One can faintly see the boot disk icon in the centre of the screen, this can only be seen when the brightness is turned down. In an attempt to solve this I turned to the 'Dead Mac Scrolls', this provided several paths for repair. The guide first suggested replacing the SN74LS38N chip, page 168. Looking back I this was probably a waste of time, being that turning down the screen brightness reveals how the screen has both video and raster. This didn't work and so my next step was to adjust the cut off on the side of the analogue board, as suggested on page 167. This also didn't work and thus I elected to replace the 2N3904 transistor on the CRT board, suggested on page 169. This also had no effect. The most recent attempt, as suggested on page 166, was to replace the R20 and R21 resistors on the analogue board. This too has resulted in failure, and I have run out of ideas as to what could be wrong. Looking through some other threads, it appears some others have had success applying the aforementioned methods but not with me. Could anyone hypothesise what is wrong and what parts should be replaced to repair it? Being a student in a remote part of England precludes swapping parts with other 68K Macs and importing a complete replacement of the analogue board due to remoteness and excessive cost. I simply must try and replace parts until it works, I don't have a community to swap boards with in my local area!
Thank you!
Thank you!