Latest news about my second board which was not booting to basic (black and white vertical stripes). I replaced a pair of capacitors (1 mfd) and now everything is ok ! I also replaced the ULA with Nebula. A second board which came back from the deads ;) Total work done on this board : - replaced TR4...
For the wrong colors, it was the ULA ! I swapped it for a working one, and the colors were back ! I have brought back one speccy to life. I even added a small switching module, which is way more power efficient than a 7805, and of course I did the composite mod. Later I'll see if I can buy a ula (ne...
Yes more or less !
Symptoms are large black and white vertical stripes.
(Last time I checked).
And voltages for lm1889 are in range... This shouldn't be the problem.
I have fixed sound thanks to the scope. On a working speccy, I could see a waveform on each side of D9. On my non working speccy, I could see a waveform on one side only... I had found the suspect ! After replacement, sound is now working ! On this board, only one problem remaining : picture is some...
After replacement of ic6, 11 & 17, spectrum is up and running. Ram chips from the c64 (4164's) are 100% working ! I was fortunate to have some spares ! Almost all the original 4116 chips were bad. For those who would like to use the ram chips from a c64, this mod is required: cut pin 1, bend pin 8, ...
Ok, thanks for your help ! I also saw that it was possible to start my smart card v2 in diag mode with the help of a switch. Then it will boot on a special diag ROM which is inside of the 16 ROMs slots in the cartridge memory. It should help me diagnose what is wrong with my speccy. I'll come back h...