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 (nebula ?), And fix the rom (vertical black and white striped) for the other partially working board.
Total work done on this spectrum :
- replaced almost all lower bank ram chips (used 5x4164 from a c64 and 3x4116 from retroleum).
- replaced d9
- replaced TR4
- replaced the ULA
- replaced 4 or 5 capacitors
- replaced the 7805 regulator with an UBEC module
- new keyboard membrane
- placed a socket for the lm1889
- composite mod
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
- replaced 4 or 5 capacitors (bad caps were responsible for vertical white and black stripes)
- replaced the ULA with Nebula (retroleum)
- replaced the beeper (sound was weak)
- will replace soon the 7805 regulator with an UBEC module. These are cheap and efficient ... already placed in a speccy, in a Timex 2048 and in a c64 power supply... I highly recommend these modules ! I recommend them over the traco modules even though they are bigger, because they can deliver up to 3 amps, while the traco can only deliver 1A I think, which is not enough in case you connect several peripherals to the speccy...