I had this machine with a video failure, some times booting with a "?" In place of the [K] cursor.. some times with a ghost character opposite to the cursor and a poor quality video output still it suddenly only gave a white screen.. a new ULA fixed it..
So be aware that a white screen doesn't always means a healthy ULA.
Sounds logical as ULA have different functions.. and building the display sync may be preserved in this case..
Faulty ULA with white screen...
Faulty ULA with white screen...
Ernesto
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come